Environmental Dermatology

The Asteraceae (formerly Compositae) family of plants is derived from the ancient Greek word aster, meaning “star,” referring to the starlike arrangement of flower petals around a central disc known as a capitulum. What initially appears as a single flower is actually a composite of several smaller flowers, hence the former name Compositae.¹ Well-known members of the Asteraceae family include ornamental annuals (eg, sunflowers, marigolds, cosmos), herbaceous ­perennials (eg, chrysanthemums, dandelions), vegetables (eg, lettuce, chicory, artichokes), herbs (eg, chamomile, tarragon), and weeds (eg, ragweed, horseweed, capeweed)(Figure 1).²

There are more than 25,000 species of Asteraceae plants that thrive in a wide range of climates worldwide. Cases of Asteraceae-induced skin reactions have been reported in North America, Europe, Asia, and Australia.³ Members of the Asteraceae family are ubiquitous in gardens, along roadsides, and in the wilderness. Occupational exposure commonly affects gardeners, florists, farmers, and forestry workers through either direct contact with plants or via airborne pollen. Furthermore, plants of the Asteraceae family are used in various products, including pediculicides (eg, insect repellents), cosmetics (eg, eye creams, body washes), and food products (eg, cooking oils, sweetening agents, coffee substitutes, herbal teas).^4-6 These plants have substantial allergic potential, resulting in numerous cutaneous reactions.

Allergic Potential

Asteraceae plants can elicit both immediate and delayed hypersensitivity reactions (HSRs); for instance, exposure to ragweed pollen may cause an IgE-mediated type 1 HSR manifesting as allergic rhinitis or a type IV HSR manifesting as airborne allergic contact dermatitis.^7,8 The main contact allergens present in Asteraceae plants are sesquiterpene lactones, which are found in the leaves, stems, flowers, and pollen.^9-11 Sesquiterpene lactones consist of an α-methyl group attached to a lactone ring combined with a sesquiterpene.¹² Patch testing can be used to diagnose Asteraceae allergy; however, the results are not consistently reliable because there is no perfect screening allergen. Patch test preparations commonly used to detect Asteraceae allergy include Compositae mix (consisting of Anthemis nobilis extract, Chamomilla recutita extract, Achillea millefolium extract, Tanacetum vulgare extract, Arnica montana extract, and parthenolide) and sesquiterpene lactone mix (consisting of alantolactone, dehydrocostus lactone, and costunolide). In North America, the prevalence of positive patch tests to Compositae mix and sesquiterpene lactone mix is approximately 2% and 0.5%, respectively.¹³ When patch testing is performed, both Compositae mix and sesquiterpene lactone mix should be utilized to minimize the risk of missing Asteraceae allergy, as sesquiterpene lactone mix alone does not detect all Compositae-sensitized patients. Additionally, it may be necessary to test supplemental Asteraceae allergens, including preparations from specific plants to which the patient has been exposed. Exposure to Asteraceae-containing cosmetic products may lead to dermatitis, though this is highly dependent on the particular plant species involved. For instance, the prevalence of sensitization is high in arnica (tincture) and elecampane but low with more commonly used species such as German chamomile.¹⁴

Cutaneous Manifestations

Asteraceae dermatitis, which also is known as Australian bush dermatitis, weed dermatitis, and chrysanthemum dermatitis,² can manifest on any area of the body that directly contacts the plant or is exposed to the pollen. Asteraceae dermatitis historically was reported in older adults with a recent history of plant exposure.^6,15 However, recent data have shown a female preponderance and a younger mean age of onset (46–49 years).¹⁶

There are multiple distinct clinical manifestations of Asteraceae dermatitis. The most common cutaneous finding is localized vesicular or eczematous patches on the hands or wrists. Other variations include eczematous rashes on the exposed skin of the hands, arms, face, and neck; generalized eczema; and isolated facial eczema.^16,17 These variations can be attributed to contact dermatitis caused by airborne pollen, which may mimic photodermatitis. However, airborne Asteraceae dermatitis can be distinguished clinically from photodermatitis by the involvement of sun-protected areas such as the skinfolds of the eyelids, retroauricular sulci, and nasolabial folds (Figure 2).^2,9 In rare cases, systemic allergic contact dermatitis can occur if the Asteraceae allergen is ingested.^2,18

Management

While complete avoidance of Asteraceae plants is ideal, it often is unrealistic due to their abundance in nature. Therefore, minimizing exposure to the causative plants is recommended. Primary preventive measures such as wearing protective gloves and clothing and applying bentonite clay prior to exposure should be taken when working outdoors. Promptly showering after contact with plants also can reduce the risk for Asteraceae dermatitis.

Symptomatic treatment is appropriate for mild cases and includes topical corticosteroids and calcineurin inhibitors. For severe cases, systemic corticosteroids may be needed for acute flares, with azathioprine, mycophenolate, cyclosporine, or methotrexate available for recalcitrant disease. Verma et al²⁵ found that treatment with azathioprine for 6 months resulted in greater than 60% clearance in all 12 patients, with a majority achieving 80% to 100% clearance. Methotrexate has been used at doses of 15 mg once weekly.²⁶ Narrowband UVB and psoralen plus UVA have been effective in extensive cases; however, care should be exercised in patients with photosensitive dermatitis, who instead should practice strict photoprotection.^27-29 Lakshmi et al³⁰ reported the use of cyclosporine during the acute phase of Asteraceae dermatitis at a dose of 2.5 mg/kg daily for 4 to 8 weeks. There have been several case reports of dupilumab treating allergic contact dermatitis; however, there have been 3 cases of patients with atopic dermatitis developing Asteraceae dermatitis while taking dupilumab.^31,32 Recently, oral Janus kinase inhibitors have shown success in treating refractory cases of airborne Asteraceae dermatitis.^33,34 Further research is needed to determine the safety and efficacy of dupilumab and Janus kinase inhibitors for treatment of Asteraceae dermatitis.

Final Thoughts

The Asteraceae plant family is vast and diverse, with more than 200 species reported to cause allergic contact dermatitis.¹² Common modes of contact include gardening, occupational exposure, airborne pollen, and use of pediculicides and cosmetics that contain components of Asteraceae plants. Educating patients on how to minimize contact with Asteraceae plants is the most effective management strategy; topical agents and oral immunosuppressives can be used for symptomatic treatment.

The Asteraceae (formerly Compositae) family of plants is derived from the ancient Greek word aster, meaning “star,” referring to the starlike arrangement of flower petals around a central disc known as a capitulum. What initially appears as a single flower is actually a composite of several smaller flowers, hence the former name Compositae.¹ Well-known members of the Asteraceae family include ornamental annuals (eg, sunflowers, marigolds, cosmos), herbaceous ­perennials (eg, chrysanthemums, dandelions), vegetables (eg, lettuce, chicory, artichokes), herbs (eg, chamomile, tarragon), and weeds (eg, ragweed, horseweed, capeweed)(Figure 1).²

There are more than 25,000 species of Asteraceae plants that thrive in a wide range of climates worldwide. Cases of Asteraceae-induced skin reactions have been reported in North America, Europe, Asia, and Australia.³ Members of the Asteraceae family are ubiquitous in gardens, along roadsides, and in the wilderness. Occupational exposure commonly affects gardeners, florists, farmers, and forestry workers through either direct contact with plants or via airborne pollen. Furthermore, plants of the Asteraceae family are used in various products, including pediculicides (eg, insect repellents), cosmetics (eg, eye creams, body washes), and food products (eg, cooking oils, sweetening agents, coffee substitutes, herbal teas).^4-6 These plants have substantial allergic potential, resulting in numerous cutaneous reactions.

Allergic Potential

Asteraceae plants can elicit both immediate and delayed hypersensitivity reactions (HSRs); for instance, exposure to ragweed pollen may cause an IgE-mediated type 1 HSR manifesting as allergic rhinitis or a type IV HSR manifesting as airborne allergic contact dermatitis.^7,8 The main contact allergens present in Asteraceae plants are sesquiterpene lactones, which are found in the leaves, stems, flowers, and pollen.^9-11 Sesquiterpene lactones consist of an α-methyl group attached to a lactone ring combined with a sesquiterpene.¹² Patch testing can be used to diagnose Asteraceae allergy; however, the results are not consistently reliable because there is no perfect screening allergen. Patch test preparations commonly used to detect Asteraceae allergy include Compositae mix (consisting of Anthemis nobilis extract, Chamomilla recutita extract, Achillea millefolium extract, Tanacetum vulgare extract, Arnica montana extract, and parthenolide) and sesquiterpene lactone mix (consisting of alantolactone, dehydrocostus lactone, and costunolide). In North America, the prevalence of positive patch tests to Compositae mix and sesquiterpene lactone mix is approximately 2% and 0.5%, respectively.¹³ When patch testing is performed, both Compositae mix and sesquiterpene lactone mix should be utilized to minimize the risk of missing Asteraceae allergy, as sesquiterpene lactone mix alone does not detect all Compositae-sensitized patients. Additionally, it may be necessary to test supplemental Asteraceae allergens, including preparations from specific plants to which the patient has been exposed. Exposure to Asteraceae-containing cosmetic products may lead to dermatitis, though this is highly dependent on the particular plant species involved. For instance, the prevalence of sensitization is high in arnica (tincture) and elecampane but low with more commonly used species such as German chamomile.¹⁴

Cutaneous Manifestations

Asteraceae dermatitis, which also is known as Australian bush dermatitis, weed dermatitis, and chrysanthemum dermatitis,² can manifest on any area of the body that directly contacts the plant or is exposed to the pollen. Asteraceae dermatitis historically was reported in older adults with a recent history of plant exposure.^6,15 However, recent data have shown a female preponderance and a younger mean age of onset (46–49 years).¹⁶

There are multiple distinct clinical manifestations of Asteraceae dermatitis. The most common cutaneous finding is localized vesicular or eczematous patches on the hands or wrists. Other variations include eczematous rashes on the exposed skin of the hands, arms, face, and neck; generalized eczema; and isolated facial eczema.^16,17 These variations can be attributed to contact dermatitis caused by airborne pollen, which may mimic photodermatitis. However, airborne Asteraceae dermatitis can be distinguished clinically from photodermatitis by the involvement of sun-protected areas such as the skinfolds of the eyelids, retroauricular sulci, and nasolabial folds (Figure 2).^2,9 In rare cases, systemic allergic contact dermatitis can occur if the Asteraceae allergen is ingested.^2,18

Management

While complete avoidance of Asteraceae plants is ideal, it often is unrealistic due to their abundance in nature. Therefore, minimizing exposure to the causative plants is recommended. Primary preventive measures such as wearing protective gloves and clothing and applying bentonite clay prior to exposure should be taken when working outdoors. Promptly showering after contact with plants also can reduce the risk for Asteraceae dermatitis.

Symptomatic treatment is appropriate for mild cases and includes topical corticosteroids and calcineurin inhibitors. For severe cases, systemic corticosteroids may be needed for acute flares, with azathioprine, mycophenolate, cyclosporine, or methotrexate available for recalcitrant disease. Verma et al²⁵ found that treatment with azathioprine for 6 months resulted in greater than 60% clearance in all 12 patients, with a majority achieving 80% to 100% clearance. Methotrexate has been used at doses of 15 mg once weekly.²⁶ Narrowband UVB and psoralen plus UVA have been effective in extensive cases; however, care should be exercised in patients with photosensitive dermatitis, who instead should practice strict photoprotection.^27-29 Lakshmi et al³⁰ reported the use of cyclosporine during the acute phase of Asteraceae dermatitis at a dose of 2.5 mg/kg daily for 4 to 8 weeks. There have been several case reports of dupilumab treating allergic contact dermatitis; however, there have been 3 cases of patients with atopic dermatitis developing Asteraceae dermatitis while taking dupilumab.^31,32 Recently, oral Janus kinase inhibitors have shown success in treating refractory cases of airborne Asteraceae dermatitis.^33,34 Further research is needed to determine the safety and efficacy of dupilumab and Janus kinase inhibitors for treatment of Asteraceae dermatitis.

Final Thoughts

The Asteraceae plant family is vast and diverse, with more than 200 species reported to cause allergic contact dermatitis.¹² Common modes of contact include gardening, occupational exposure, airborne pollen, and use of pediculicides and cosmetics that contain components of Asteraceae plants. Educating patients on how to minimize contact with Asteraceae plants is the most effective management strategy; topical agents and oral immunosuppressives can be used for symptomatic treatment.

The Asteraceae (formerly Compositae) family of plants is derived from the ancient Greek word aster, meaning “star,” referring to the starlike arrangement of flower petals around a central disc known as a capitulum. What initially appears as a single flower is actually a composite of several smaller flowers, hence the former name Compositae.¹ Well-known members of the Asteraceae family include ornamental annuals (eg, sunflowers, marigolds, cosmos), herbaceous ­perennials (eg, chrysanthemums, dandelions), vegetables (eg, lettuce, chicory, artichokes), herbs (eg, chamomile, tarragon), and weeds (eg, ragweed, horseweed, capeweed)(Figure 1).²

There are more than 25,000 species of Asteraceae plants that thrive in a wide range of climates worldwide. Cases of Asteraceae-induced skin reactions have been reported in North America, Europe, Asia, and Australia.³ Members of the Asteraceae family are ubiquitous in gardens, along roadsides, and in the wilderness. Occupational exposure commonly affects gardeners, florists, farmers, and forestry workers through either direct contact with plants or via airborne pollen. Furthermore, plants of the Asteraceae family are used in various products, including pediculicides (eg, insect repellents), cosmetics (eg, eye creams, body washes), and food products (eg, cooking oils, sweetening agents, coffee substitutes, herbal teas).^4-6 These plants have substantial allergic potential, resulting in numerous cutaneous reactions.

Allergic Potential

Asteraceae plants can elicit both immediate and delayed hypersensitivity reactions (HSRs); for instance, exposure to ragweed pollen may cause an IgE-mediated type 1 HSR manifesting as allergic rhinitis or a type IV HSR manifesting as airborne allergic contact dermatitis.^7,8 The main contact allergens present in Asteraceae plants are sesquiterpene lactones, which are found in the leaves, stems, flowers, and pollen.^9-11 Sesquiterpene lactones consist of an α-methyl group attached to a lactone ring combined with a sesquiterpene.¹² Patch testing can be used to diagnose Asteraceae allergy; however, the results are not consistently reliable because there is no perfect screening allergen. Patch test preparations commonly used to detect Asteraceae allergy include Compositae mix (consisting of Anthemis nobilis extract, Chamomilla recutita extract, Achillea millefolium extract, Tanacetum vulgare extract, Arnica montana extract, and parthenolide) and sesquiterpene lactone mix (consisting of alantolactone, dehydrocostus lactone, and costunolide). In North America, the prevalence of positive patch tests to Compositae mix and sesquiterpene lactone mix is approximately 2% and 0.5%, respectively.¹³ When patch testing is performed, both Compositae mix and sesquiterpene lactone mix should be utilized to minimize the risk of missing Asteraceae allergy, as sesquiterpene lactone mix alone does not detect all Compositae-sensitized patients. Additionally, it may be necessary to test supplemental Asteraceae allergens, including preparations from specific plants to which the patient has been exposed. Exposure to Asteraceae-containing cosmetic products may lead to dermatitis, though this is highly dependent on the particular plant species involved. For instance, the prevalence of sensitization is high in arnica (tincture) and elecampane but low with more commonly used species such as German chamomile.¹⁴

Cutaneous Manifestations

Asteraceae dermatitis, which also is known as Australian bush dermatitis, weed dermatitis, and chrysanthemum dermatitis,² can manifest on any area of the body that directly contacts the plant or is exposed to the pollen. Asteraceae dermatitis historically was reported in older adults with a recent history of plant exposure.^6,15 However, recent data have shown a female preponderance and a younger mean age of onset (46–49 years).¹⁶

There are multiple distinct clinical manifestations of Asteraceae dermatitis. The most common cutaneous finding is localized vesicular or eczematous patches on the hands or wrists. Other variations include eczematous rashes on the exposed skin of the hands, arms, face, and neck; generalized eczema; and isolated facial eczema.^16,17 These variations can be attributed to contact dermatitis caused by airborne pollen, which may mimic photodermatitis. However, airborne Asteraceae dermatitis can be distinguished clinically from photodermatitis by the involvement of sun-protected areas such as the skinfolds of the eyelids, retroauricular sulci, and nasolabial folds (Figure 2).^2,9 In rare cases, systemic allergic contact dermatitis can occur if the Asteraceae allergen is ingested.^2,18

Management

While complete avoidance of Asteraceae plants is ideal, it often is unrealistic due to their abundance in nature. Therefore, minimizing exposure to the causative plants is recommended. Primary preventive measures such as wearing protective gloves and clothing and applying bentonite clay prior to exposure should be taken when working outdoors. Promptly showering after contact with plants also can reduce the risk for Asteraceae dermatitis.

Symptomatic treatment is appropriate for mild cases and includes topical corticosteroids and calcineurin inhibitors. For severe cases, systemic corticosteroids may be needed for acute flares, with azathioprine, mycophenolate, cyclosporine, or methotrexate available for recalcitrant disease. Verma et al²⁵ found that treatment with azathioprine for 6 months resulted in greater than 60% clearance in all 12 patients, with a majority achieving 80% to 100% clearance. Methotrexate has been used at doses of 15 mg once weekly.²⁶ Narrowband UVB and psoralen plus UVA have been effective in extensive cases; however, care should be exercised in patients with photosensitive dermatitis, who instead should practice strict photoprotection.^27-29 Lakshmi et al³⁰ reported the use of cyclosporine during the acute phase of Asteraceae dermatitis at a dose of 2.5 mg/kg daily for 4 to 8 weeks. There have been several case reports of dupilumab treating allergic contact dermatitis; however, there have been 3 cases of patients with atopic dermatitis developing Asteraceae dermatitis while taking dupilumab.^31,32 Recently, oral Janus kinase inhibitors have shown success in treating refractory cases of airborne Asteraceae dermatitis.^33,34 Further research is needed to determine the safety and efficacy of dupilumab and Janus kinase inhibitors for treatment of Asteraceae dermatitis.

Final Thoughts

The Asteraceae plant family is vast and diverse, with more than 200 species reported to cause allergic contact dermatitis.¹² Common modes of contact include gardening, occupational exposure, airborne pollen, and use of pediculicides and cosmetics that contain components of Asteraceae plants. Educating patients on how to minimize contact with Asteraceae plants is the most effective management strategy; topical agents and oral immunosuppressives can be used for symptomatic treatment.

There are 375 species of poisonous snakes, with approximately 20,000 deaths worldwide each year due to snakebites, mostly in Asia and Africa.¹ The death rate in the United States is 14 to 20 cases per year. In the United States, a variety of rattlesnakes are poisonous. There are 2 genera of rattlesnakes: Sistrurus (3 species) and Crotalus (23 species). The pygmy rattlesnake belongs to the Sistrurus miliarius species that is divided into 3 subspecies: the Carolina pigmy rattlesnake (S miliarius miliarius), the western pygmy rattlesnake (S miliarius streckeri), and the dusky pygmy rattlesnake (S miliarius barbouri).²

The western pygmy rattlesnake belongs to the Crotalidae family. The rattlesnakes in this family also are known as pit vipers. All pit vipers have common characteristics for identification: triangular head, fangs, elliptical pupils, and a heat-sensing pit between the eyes. The western pygmy rattlesnake is found in Missouri, Arkansas, Oklahoma, Kentucky, and Tennessee.¹ It is small bodied (15–20 inches)³ and grayish-brown, with a brown dorsal stripe with black blotches on its back. It is found in glades, second-growth forests near rock ledges, and areas where powerlines cut through dense forest.³ Its venom is hemorrhagic, causing tissue damage, but does not contain neurotoxins.⁴ Bites from the western pygmy rattlesnake often do not lead to death, but the venom, which contains numerous proteins and enzymes, does cause necrotic hemorrhagic ulceration at the site of envenomation and possible loss of digit.^5,6

We present a case of a man who was bitten on the right third digit by a western pygmy rattlesnake. We describe the clinical course and treatment.

Case Report

A 56-year-old right-handed man presented to the emergency department with a rapidly swelling, painful hand following a snakebite to the dorsal aspect of the right third digit (Figure 1). He was able to capture a photograph of the snake at the time of injury, which helped identify it as a western pygmy rattlesnake (Figure 2). He also photographed the hand immediately after the bite occurred (Figure 3). Vitals on presentation included an elevated blood pressure of 161/100 mm Hg; no fever (temperature, 36.4 °C); and normal pulse oximetry of 98%, pulse of 86 beats per minute, and respiratory rate of 16 breaths per minute.

After the snakebite, the patient’s family called the Missouri Poison Center immediately. The family identified the snake species and shared this information with the poison center. Poison control recommended calling the nearest hospitals to determine if antivenom was available and make notification of arrival. 

The patient’s tetanus toxoid immunization was updated immediately upon arrival. The hand was marked to monitor swelling. Initial laboratory test results revealed the following values: sodium, 133 mmol/L (reference range, 136–145 mmol/L); potassium, 3.4 mmol/L (3.6–5.2 mmol/L); lactic acid, 2.4 mmol/L (0.5–2.2 mmol/L); creatine kinase, 425 U/L (55–170 U/L); platelet count, 68/µL (150,000–450,000/µL); fibrinogen, 169 mg/dL (185–410 mg/dL); and glucose, 121 mg/dL (74–106 mg/dL). The remainder of the complete blood cell count and metabolic panel was unremarkable. Radiographs of the hand did not show any fractures, dislocations, or foreign bodies. Missouri Poison Center was consulted. Given the patient’s severe pain, edema beyond 40 cm, and developing ecchymosis on the inner arm, the bite was graded as a 3 on the traditional snakebite severity scale. Poison control recommended 4 to 6 vials of antivenom over 60 minutes. Six vials of Crotalidae polyvalent immune fab antivenom were given.

The patient’s complete blood cell count remained unremarkable throughout his admission. His metabolic panel returned to normal at 6 hours postadmission: sodium, 139 mmol/L; potassium, 4.0 mmol/L. His lactate and creatinine kinase were not rechecked. His fibrinogen was trending upward. Serial laboratory test results revealed fibrinogen levels of 153, 158, 161, 159, 173, and 216 mg/dL at 6, 12, 18, 24, 30, and 36 hours, respectively. Other laboratory test results including prothrombin time (11.0 s) and international normalized ratio (0.98) remained within reference range (11–13 s and 0.80–1.39, respectively) during serial monitoring.

The patient was hospitalized for 40 hours while waiting for his fibrinogen level to normalize. The local skin necrosis worsened acutely in this 40-hour window (Figure 4). Intravenous antibiotics were not administered during the hospital stay. Before discharge, the patient was evaluated by the surgery service, who did not recommend debridement.

Surgical Management of Snakebites

The surgeon’s role in managing snakebites is controversial. Snakebites were once perceived as a surgical emergency due to symptoms mimicking compartment syndrome; however, snakebites rarely cause a true compartment syndrome.⁷ Prophylactic bite excision and fasciotomies are not recommended. Incision and suction of the fang marks may be beneficial if performed within 15 to 30 minutes from the time of the bite.⁸ With access to a surgeon in this short time period being nearly impossible, incision and suctioning of fang marks generally is not recommended.⁹ Retained snake fangs are a possibility, and the infection could spread to a nearby joint, causing septic arthritis,¹⁰ which would be an indication for surgical intervention. Bites to the finger often cause major swelling, and the benefits of dermotomy are documented.¹¹ Generally, early administration of antivenom will decrease local tissue reaction and prevent additional tissue loss.¹² In our patient, the decision to perform dermotomy was made when the area of necrosis had declared itself and the skin reached its elastic limit. Bozkurt et al¹³ described the neurovascular bundles within the digit as functioning as small compartments. When the skin of the digit reaches its elastic limit, pressure within the compartment may exceed the capillary closing pressure, and the integrity of small vessels and nerves may be compromised. Our case highlights the benefit of dermotomy as well as the functional and cosmetic results that can be achieved.

Wound Care for Snakebites

There is little published on the treatment of snakebites after patients are stabilized medically for hospital discharge. Venomous snakes inject toxins that predominantly consist of enzymes (eg, phospholipase A2, phosphodiesterase, hyaluronidase, peptidase, metalloproteinase) that cause tissue destruction through diverse mechanisms.¹⁴ The venom of western pygmy rattlesnakes is hemotoxic and can cause necrotic hemorrhagic ulceration,⁴ as was the case in our patient.

Silver sulfadiazine commonly is used to prevent infection in burn patients. Given the large surface area of exposed dermis after debridement and concern for infection, silver sulfadiazine was chosen in our patient for local wound care treatment. Silver sulfadiazine is a widely available and low-cost drug.¹⁵ Its antibacterial effects are due to the silver ions, which only act superficially and therefore limit systemic absorption.¹⁶ Application should be performed in a clean manner with minimal trauma to the tissue. This technique is best achieved by using sterile gloves and applying the medication manually. A 0.0625-inch layer should be applied to entirely cover the cleaned debrided area.¹⁷ When performing application with tongue blades or cotton swabs, it is important to never “double dip.” Patient education on proper administration is imperative to a successful outcome.

Final Thoughts

Our case demonstrates the safe use of Crotalidae polyvalent immune fab antivenom for the treatment of western pygmy rattlesnake (S miliarius streckeri) envenomation. Early administration of antivenom following pit viper rattlesnake envenomations is important to mitigate systemic effects and the extent of soft tissue damage. There are few studies on local wound care treatment after rattlesnake envenomation. This case highlights the role of dermotomy and wound care with silver sulfadiazine cream 1%.

There are 375 species of poisonous snakes, with approximately 20,000 deaths worldwide each year due to snakebites, mostly in Asia and Africa.¹ The death rate in the United States is 14 to 20 cases per year. In the United States, a variety of rattlesnakes are poisonous. There are 2 genera of rattlesnakes: Sistrurus (3 species) and Crotalus (23 species). The pygmy rattlesnake belongs to the Sistrurus miliarius species that is divided into 3 subspecies: the Carolina pigmy rattlesnake (S miliarius miliarius), the western pygmy rattlesnake (S miliarius streckeri), and the dusky pygmy rattlesnake (S miliarius barbouri).²

The western pygmy rattlesnake belongs to the Crotalidae family. The rattlesnakes in this family also are known as pit vipers. All pit vipers have common characteristics for identification: triangular head, fangs, elliptical pupils, and a heat-sensing pit between the eyes. The western pygmy rattlesnake is found in Missouri, Arkansas, Oklahoma, Kentucky, and Tennessee.¹ It is small bodied (15–20 inches)³ and grayish-brown, with a brown dorsal stripe with black blotches on its back. It is found in glades, second-growth forests near rock ledges, and areas where powerlines cut through dense forest.³ Its venom is hemorrhagic, causing tissue damage, but does not contain neurotoxins.⁴ Bites from the western pygmy rattlesnake often do not lead to death, but the venom, which contains numerous proteins and enzymes, does cause necrotic hemorrhagic ulceration at the site of envenomation and possible loss of digit.^5,6

We present a case of a man who was bitten on the right third digit by a western pygmy rattlesnake. We describe the clinical course and treatment.

Case Report

A 56-year-old right-handed man presented to the emergency department with a rapidly swelling, painful hand following a snakebite to the dorsal aspect of the right third digit (Figure 1). He was able to capture a photograph of the snake at the time of injury, which helped identify it as a western pygmy rattlesnake (Figure 2). He also photographed the hand immediately after the bite occurred (Figure 3). Vitals on presentation included an elevated blood pressure of 161/100 mm Hg; no fever (temperature, 36.4 °C); and normal pulse oximetry of 98%, pulse of 86 beats per minute, and respiratory rate of 16 breaths per minute.

After the snakebite, the patient’s family called the Missouri Poison Center immediately. The family identified the snake species and shared this information with the poison center. Poison control recommended calling the nearest hospitals to determine if antivenom was available and make notification of arrival. 

The patient’s tetanus toxoid immunization was updated immediately upon arrival. The hand was marked to monitor swelling. Initial laboratory test results revealed the following values: sodium, 133 mmol/L (reference range, 136–145 mmol/L); potassium, 3.4 mmol/L (3.6–5.2 mmol/L); lactic acid, 2.4 mmol/L (0.5–2.2 mmol/L); creatine kinase, 425 U/L (55–170 U/L); platelet count, 68/µL (150,000–450,000/µL); fibrinogen, 169 mg/dL (185–410 mg/dL); and glucose, 121 mg/dL (74–106 mg/dL). The remainder of the complete blood cell count and metabolic panel was unremarkable. Radiographs of the hand did not show any fractures, dislocations, or foreign bodies. Missouri Poison Center was consulted. Given the patient’s severe pain, edema beyond 40 cm, and developing ecchymosis on the inner arm, the bite was graded as a 3 on the traditional snakebite severity scale. Poison control recommended 4 to 6 vials of antivenom over 60 minutes. Six vials of Crotalidae polyvalent immune fab antivenom were given.

The patient’s complete blood cell count remained unremarkable throughout his admission. His metabolic panel returned to normal at 6 hours postadmission: sodium, 139 mmol/L; potassium, 4.0 mmol/L. His lactate and creatinine kinase were not rechecked. His fibrinogen was trending upward. Serial laboratory test results revealed fibrinogen levels of 153, 158, 161, 159, 173, and 216 mg/dL at 6, 12, 18, 24, 30, and 36 hours, respectively. Other laboratory test results including prothrombin time (11.0 s) and international normalized ratio (0.98) remained within reference range (11–13 s and 0.80–1.39, respectively) during serial monitoring.

The patient was hospitalized for 40 hours while waiting for his fibrinogen level to normalize. The local skin necrosis worsened acutely in this 40-hour window (Figure 4). Intravenous antibiotics were not administered during the hospital stay. Before discharge, the patient was evaluated by the surgery service, who did not recommend debridement.

Surgical Management of Snakebites

The surgeon’s role in managing snakebites is controversial. Snakebites were once perceived as a surgical emergency due to symptoms mimicking compartment syndrome; however, snakebites rarely cause a true compartment syndrome.⁷ Prophylactic bite excision and fasciotomies are not recommended. Incision and suction of the fang marks may be beneficial if performed within 15 to 30 minutes from the time of the bite.⁸ With access to a surgeon in this short time period being nearly impossible, incision and suctioning of fang marks generally is not recommended.⁹ Retained snake fangs are a possibility, and the infection could spread to a nearby joint, causing septic arthritis,¹⁰ which would be an indication for surgical intervention. Bites to the finger often cause major swelling, and the benefits of dermotomy are documented.¹¹ Generally, early administration of antivenom will decrease local tissue reaction and prevent additional tissue loss.¹² In our patient, the decision to perform dermotomy was made when the area of necrosis had declared itself and the skin reached its elastic limit. Bozkurt et al¹³ described the neurovascular bundles within the digit as functioning as small compartments. When the skin of the digit reaches its elastic limit, pressure within the compartment may exceed the capillary closing pressure, and the integrity of small vessels and nerves may be compromised. Our case highlights the benefit of dermotomy as well as the functional and cosmetic results that can be achieved.

Wound Care for Snakebites

There is little published on the treatment of snakebites after patients are stabilized medically for hospital discharge. Venomous snakes inject toxins that predominantly consist of enzymes (eg, phospholipase A2, phosphodiesterase, hyaluronidase, peptidase, metalloproteinase) that cause tissue destruction through diverse mechanisms.¹⁴ The venom of western pygmy rattlesnakes is hemotoxic and can cause necrotic hemorrhagic ulceration,⁴ as was the case in our patient.

Silver sulfadiazine commonly is used to prevent infection in burn patients. Given the large surface area of exposed dermis after debridement and concern for infection, silver sulfadiazine was chosen in our patient for local wound care treatment. Silver sulfadiazine is a widely available and low-cost drug.¹⁵ Its antibacterial effects are due to the silver ions, which only act superficially and therefore limit systemic absorption.¹⁶ Application should be performed in a clean manner with minimal trauma to the tissue. This technique is best achieved by using sterile gloves and applying the medication manually. A 0.0625-inch layer should be applied to entirely cover the cleaned debrided area.¹⁷ When performing application with tongue blades or cotton swabs, it is important to never “double dip.” Patient education on proper administration is imperative to a successful outcome.

Final Thoughts

Our case demonstrates the safe use of Crotalidae polyvalent immune fab antivenom for the treatment of western pygmy rattlesnake (S miliarius streckeri) envenomation. Early administration of antivenom following pit viper rattlesnake envenomations is important to mitigate systemic effects and the extent of soft tissue damage. There are few studies on local wound care treatment after rattlesnake envenomation. This case highlights the role of dermotomy and wound care with silver sulfadiazine cream 1%.

There are 375 species of poisonous snakes, with approximately 20,000 deaths worldwide each year due to snakebites, mostly in Asia and Africa.¹ The death rate in the United States is 14 to 20 cases per year. In the United States, a variety of rattlesnakes are poisonous. There are 2 genera of rattlesnakes: Sistrurus (3 species) and Crotalus (23 species). The pygmy rattlesnake belongs to the Sistrurus miliarius species that is divided into 3 subspecies: the Carolina pigmy rattlesnake (S miliarius miliarius), the western pygmy rattlesnake (S miliarius streckeri), and the dusky pygmy rattlesnake (S miliarius barbouri).²

The western pygmy rattlesnake belongs to the Crotalidae family. The rattlesnakes in this family also are known as pit vipers. All pit vipers have common characteristics for identification: triangular head, fangs, elliptical pupils, and a heat-sensing pit between the eyes. The western pygmy rattlesnake is found in Missouri, Arkansas, Oklahoma, Kentucky, and Tennessee.¹ It is small bodied (15–20 inches)³ and grayish-brown, with a brown dorsal stripe with black blotches on its back. It is found in glades, second-growth forests near rock ledges, and areas where powerlines cut through dense forest.³ Its venom is hemorrhagic, causing tissue damage, but does not contain neurotoxins.⁴ Bites from the western pygmy rattlesnake often do not lead to death, but the venom, which contains numerous proteins and enzymes, does cause necrotic hemorrhagic ulceration at the site of envenomation and possible loss of digit.^5,6

We present a case of a man who was bitten on the right third digit by a western pygmy rattlesnake. We describe the clinical course and treatment.

Case Report

A 56-year-old right-handed man presented to the emergency department with a rapidly swelling, painful hand following a snakebite to the dorsal aspect of the right third digit (Figure 1). He was able to capture a photograph of the snake at the time of injury, which helped identify it as a western pygmy rattlesnake (Figure 2). He also photographed the hand immediately after the bite occurred (Figure 3). Vitals on presentation included an elevated blood pressure of 161/100 mm Hg; no fever (temperature, 36.4 °C); and normal pulse oximetry of 98%, pulse of 86 beats per minute, and respiratory rate of 16 breaths per minute.

After the snakebite, the patient’s family called the Missouri Poison Center immediately. The family identified the snake species and shared this information with the poison center. Poison control recommended calling the nearest hospitals to determine if antivenom was available and make notification of arrival. 

The patient’s tetanus toxoid immunization was updated immediately upon arrival. The hand was marked to monitor swelling. Initial laboratory test results revealed the following values: sodium, 133 mmol/L (reference range, 136–145 mmol/L); potassium, 3.4 mmol/L (3.6–5.2 mmol/L); lactic acid, 2.4 mmol/L (0.5–2.2 mmol/L); creatine kinase, 425 U/L (55–170 U/L); platelet count, 68/µL (150,000–450,000/µL); fibrinogen, 169 mg/dL (185–410 mg/dL); and glucose, 121 mg/dL (74–106 mg/dL). The remainder of the complete blood cell count and metabolic panel was unremarkable. Radiographs of the hand did not show any fractures, dislocations, or foreign bodies. Missouri Poison Center was consulted. Given the patient’s severe pain, edema beyond 40 cm, and developing ecchymosis on the inner arm, the bite was graded as a 3 on the traditional snakebite severity scale. Poison control recommended 4 to 6 vials of antivenom over 60 minutes. Six vials of Crotalidae polyvalent immune fab antivenom were given.

The patient’s complete blood cell count remained unremarkable throughout his admission. His metabolic panel returned to normal at 6 hours postadmission: sodium, 139 mmol/L; potassium, 4.0 mmol/L. His lactate and creatinine kinase were not rechecked. His fibrinogen was trending upward. Serial laboratory test results revealed fibrinogen levels of 153, 158, 161, 159, 173, and 216 mg/dL at 6, 12, 18, 24, 30, and 36 hours, respectively. Other laboratory test results including prothrombin time (11.0 s) and international normalized ratio (0.98) remained within reference range (11–13 s and 0.80–1.39, respectively) during serial monitoring.

The patient was hospitalized for 40 hours while waiting for his fibrinogen level to normalize. The local skin necrosis worsened acutely in this 40-hour window (Figure 4). Intravenous antibiotics were not administered during the hospital stay. Before discharge, the patient was evaluated by the surgery service, who did not recommend debridement.

Surgical Management of Snakebites

The surgeon’s role in managing snakebites is controversial. Snakebites were once perceived as a surgical emergency due to symptoms mimicking compartment syndrome; however, snakebites rarely cause a true compartment syndrome.⁷ Prophylactic bite excision and fasciotomies are not recommended. Incision and suction of the fang marks may be beneficial if performed within 15 to 30 minutes from the time of the bite.⁸ With access to a surgeon in this short time period being nearly impossible, incision and suctioning of fang marks generally is not recommended.⁹ Retained snake fangs are a possibility, and the infection could spread to a nearby joint, causing septic arthritis,¹⁰ which would be an indication for surgical intervention. Bites to the finger often cause major swelling, and the benefits of dermotomy are documented.¹¹ Generally, early administration of antivenom will decrease local tissue reaction and prevent additional tissue loss.¹² In our patient, the decision to perform dermotomy was made when the area of necrosis had declared itself and the skin reached its elastic limit. Bozkurt et al¹³ described the neurovascular bundles within the digit as functioning as small compartments. When the skin of the digit reaches its elastic limit, pressure within the compartment may exceed the capillary closing pressure, and the integrity of small vessels and nerves may be compromised. Our case highlights the benefit of dermotomy as well as the functional and cosmetic results that can be achieved.

Wound Care for Snakebites

There is little published on the treatment of snakebites after patients are stabilized medically for hospital discharge. Venomous snakes inject toxins that predominantly consist of enzymes (eg, phospholipase A2, phosphodiesterase, hyaluronidase, peptidase, metalloproteinase) that cause tissue destruction through diverse mechanisms.¹⁴ The venom of western pygmy rattlesnakes is hemotoxic and can cause necrotic hemorrhagic ulceration,⁴ as was the case in our patient.

Silver sulfadiazine commonly is used to prevent infection in burn patients. Given the large surface area of exposed dermis after debridement and concern for infection, silver sulfadiazine was chosen in our patient for local wound care treatment. Silver sulfadiazine is a widely available and low-cost drug.¹⁵ Its antibacterial effects are due to the silver ions, which only act superficially and therefore limit systemic absorption.¹⁶ Application should be performed in a clean manner with minimal trauma to the tissue. This technique is best achieved by using sterile gloves and applying the medication manually. A 0.0625-inch layer should be applied to entirely cover the cleaned debrided area.¹⁷ When performing application with tongue blades or cotton swabs, it is important to never “double dip.” Patient education on proper administration is imperative to a successful outcome.

Final Thoughts

Our case demonstrates the safe use of Crotalidae polyvalent immune fab antivenom for the treatment of western pygmy rattlesnake (S miliarius streckeri) envenomation. Early administration of antivenom following pit viper rattlesnake envenomations is important to mitigate systemic effects and the extent of soft tissue damage. There are few studies on local wound care treatment after rattlesnake envenomation. This case highlights the role of dermotomy and wound care with silver sulfadiazine cream 1%.

The mango tree (Mangifera indica) produces ­nutrient-dense fruit—known colloquially as the “king of fruits”—that is widely consumed across the world. Native to southern Asia, the mango tree is a member of the Anacardiaceae family, a large family of flowering, fruit-bearing plants.¹ Many members of the Anacardiaceae family, which includes poison ivy and poison oak, are known to produce urushiol, a skin irritant associated with allergic contact dermatitis (ACD).² Interestingly, despite its widespread consumption and categorization in the Anacardiaceae family, allergic reactions to mango are comparatively rare; they occur as either immediate type I hypersensitivity reactions manifesting with rapid-onset symptoms such as urticaria, wheezing, and angioedema, or delayed type IV hypersensitivity reactions manifesting as ACD.³ Although exposure to components of the mango tree has been most characteristically linked to type IV hypersensitivity reactions, there remain fewer than 40 reported cases of mango-induced ACD since it was first described in 1939.⁴

Evaluation of ACD most commonly includes a thorough clinical assessment with diagnostic support from patch testing and histopathologic review following skin biopsy. In recent years, reflectance confocal microscopy (RCM) has shown promising potential to join the ­repertoire of diagnostic tools for ACD by enabling dynamic and high-resolution imaging of contact dermatitis in vivo.^5-10 Reflectance confocal microscopy is a noninvasive optical imaging technique that uses a low-energy diode laser to penetrate the layers of the skin. The resulting reflected light generates images that facilitate visualization of cutaneous structures to the depth of the papillary dermis.¹¹ While it is most commonly used in skin cancer diagnostics, preliminary studies also have shown an emerging role for RCM in the evaluation of eczematous and inflammatory skin disease, including contact dermatitis.^5-10 Herein, we present a unique case of mango sap–induced ACD imaged and diagnosed in real time via RCM.

Case Report

A 39-year-old woman presented to our clinic with a pruritic vesicular eruption on the right leg of 2 weeks’ duration that initially had developed within 7 days of exposure to mango tree sap (Figure 1). The patient reported having experienced similar pruritic eruptions in the past following contact with mango sap while eating mangos but denied any history of reactions from ingestion of the fruit. She also reported a history of robust reactions to poison ivy; however, a timeline specifying the order of first exposure to these irritants was unknown. She denied any personal or family history of atopic conditions.

The affected skin was imaged in real time during clinic using RCM, which showed an inflammatory infiltrate represented by dark spongiotic vesicles containing bright cells (Figure 2). Additional RCM imaging at the level of the stratum spinosum showed dark spongiotic areas with bright inflammatory cells infiltrating the vesicles, which were surrounded by normal skin showing a typical epidermal honeycomb pattern (Figure 3). These findings were diagnostic of ACD secondary to exposure to mango sap. The patient was advised to apply clobetasol cream 0.05% to the affected area. Notable improvement of the rash was noted within 10 days of treatment.

Comment

Exposure to the mango tree and its fruit is a rare cause of ACD, with few reported cases in the literature. The majority of known instances have occurred in non–mango-cultivating countries, largely the United States, although cases also have been reported in Canada, Australia, France, Japan, and Thailand.^3,12 Mango-induced contact allergy follows a roughly equal distribution between males and females and most often occurs in young adults during the third and fourth decades of life.^4,12-21 Importantly, delayed-type hypersensitivity reactions to mango can manifest as either localized or systemic ACD. Localized ACD can be induced via direct contact with the mango tree and its components or ingestion of the fruit.^3,12,22 Conversely, systemic ACD is primarily stimulated by ingestion of the fruit. In our case, the patient had no history of allergy following mango ingestion, and her ACD was prompted by isolated contact with mango sap. The time from exposure to symptom onset of known instances of mango ACD varies widely, ranging from less than 24 hours to as long as 9 days.^3,12 Diagnosis of mango-induced ACD largely is guided by clinical findings. Presenting symptoms often include an eczematous, vesicular, pruritic rash on affected areas of the skin, frequently the head, neck, and extremities. Patients also commonly present with linear papulovesicular lesions and periorbital or perioral edema.

The suspected allergens responsible for mango-induced ACD are derived from resorcinol—specifically heptadecadienyl resorcinol, heptadecenyl resorcinol, and pentadecyl resorcinol, which are collectively known as mango allergens.²³ These allergens can be found within the pulp and skin of the mango fruit as well as in the bark and leaves of the mango tree, which may explain observed allergic reactions to components of both the mango fruit and tree.¹² Similar to these resorcinol derivatives, the urushiol resin found in poison ivy and poison oak is a catechol derivative.² Importantly, both resorcinols and catechols are isomers of the same aromatic ­phenol—dihydroxybenzene. Because of these similarities, it is thought that the allergens in mangos may cross-react with urushiol in poison ivy or poison oak.²³ Alongside their shared categorization in the Anacardiaceae family, it is hypothesized that this cross-reactivity underlies the sensitization that has been noted between mango and poison ivy or poison oak exposure.^12,23,24 Thus, ACD often can occur on initial contact with the mango tree or its components, as a prior exposure to poison ivy or poison oak may serve as the inciting factor for hypersensitization. The majority of reported cases in the literature also occurred in countries where exposure to poison ivy and poison oak are common, further supporting the notion that these compounds may provide a sensitizing trigger for a future mango contact allergy.¹²

A detailed clinical history combined with adjunctive diagnostic support from patch testing and histopathology of biopsied skin lesions classically are used in the diagnosis of mango-induced ACD. Due to its ability to provide quick and noninvasive in vivo imaging of cutaneous lesions, RCM's applications have expanded to include evaluation of inflammatory skin diseases such as contact dermatitis. Many features of contact dermatitis identified via RCM are common between ACD and irritant contact dermatitis (ICD) and include disruption of the stratum corneum, parakeratosis, vesiculation, spongiosis, and exocytosis.^6,10,25 Studies also have described features shown via RCM that are unique to ACD, including vasodilation and intercellular edema, compared to more distinct targetoid keratinocytes and detached corneocytes seen in ICD.^6,10,25 Studies by Astner et al^5,6 demonstrated a wide range of sensitivity from 52% to 96% and a high specificity of RCM greater than 95% for many of the aforementioned features of contact dermatitis, including disruption of the stratum corneum, parakeratosis, spongiosis, and exocytosis. Additional studies have further strengthened these findings, demonstrating sensitivity and specificity values of 83% and 92% for contact dermatitis under RCM, respectively.²⁶ Importantly, given the similarities and potentially large overlap of features between ACD and ICD identified via RCM as well as findings seen on physical examination and histopathology, an emphasis on clinical correlation is essential when differentiating between these 2 variants of contact dermatitis. Thus, taken in consideration with clinical contexts, RCM has shown potent diagnostic accuracy and great potential to support the evaluation of ACD alongside patch testing and histopathology.

Final Thoughts

Contact allergy to the mango tree and its components is uncommon. We report a unique case of mango sap–induced ACD evaluated and diagnosed via dynamic visualization under RCM. As a noninvasive and reproducible imaging technique with resolutions comparable to histopathologic analysis, RCM is a promising tool that can be used to support the diagnostic evaluation of ACD.

The mango tree (Mangifera indica) produces ­nutrient-dense fruit—known colloquially as the “king of fruits”—that is widely consumed across the world. Native to southern Asia, the mango tree is a member of the Anacardiaceae family, a large family of flowering, fruit-bearing plants.¹ Many members of the Anacardiaceae family, which includes poison ivy and poison oak, are known to produce urushiol, a skin irritant associated with allergic contact dermatitis (ACD).² Interestingly, despite its widespread consumption and categorization in the Anacardiaceae family, allergic reactions to mango are comparatively rare; they occur as either immediate type I hypersensitivity reactions manifesting with rapid-onset symptoms such as urticaria, wheezing, and angioedema, or delayed type IV hypersensitivity reactions manifesting as ACD.³ Although exposure to components of the mango tree has been most characteristically linked to type IV hypersensitivity reactions, there remain fewer than 40 reported cases of mango-induced ACD since it was first described in 1939.⁴

Evaluation of ACD most commonly includes a thorough clinical assessment with diagnostic support from patch testing and histopathologic review following skin biopsy. In recent years, reflectance confocal microscopy (RCM) has shown promising potential to join the ­repertoire of diagnostic tools for ACD by enabling dynamic and high-resolution imaging of contact dermatitis in vivo.^5-10 Reflectance confocal microscopy is a noninvasive optical imaging technique that uses a low-energy diode laser to penetrate the layers of the skin. The resulting reflected light generates images that facilitate visualization of cutaneous structures to the depth of the papillary dermis.¹¹ While it is most commonly used in skin cancer diagnostics, preliminary studies also have shown an emerging role for RCM in the evaluation of eczematous and inflammatory skin disease, including contact dermatitis.^5-10 Herein, we present a unique case of mango sap–induced ACD imaged and diagnosed in real time via RCM.

Case Report

A 39-year-old woman presented to our clinic with a pruritic vesicular eruption on the right leg of 2 weeks’ duration that initially had developed within 7 days of exposure to mango tree sap (Figure 1). The patient reported having experienced similar pruritic eruptions in the past following contact with mango sap while eating mangos but denied any history of reactions from ingestion of the fruit. She also reported a history of robust reactions to poison ivy; however, a timeline specifying the order of first exposure to these irritants was unknown. She denied any personal or family history of atopic conditions.

The affected skin was imaged in real time during clinic using RCM, which showed an inflammatory infiltrate represented by dark spongiotic vesicles containing bright cells (Figure 2). Additional RCM imaging at the level of the stratum spinosum showed dark spongiotic areas with bright inflammatory cells infiltrating the vesicles, which were surrounded by normal skin showing a typical epidermal honeycomb pattern (Figure 3). These findings were diagnostic of ACD secondary to exposure to mango sap. The patient was advised to apply clobetasol cream 0.05% to the affected area. Notable improvement of the rash was noted within 10 days of treatment.

Comment

Exposure to the mango tree and its fruit is a rare cause of ACD, with few reported cases in the literature. The majority of known instances have occurred in non–mango-cultivating countries, largely the United States, although cases also have been reported in Canada, Australia, France, Japan, and Thailand.^3,12 Mango-induced contact allergy follows a roughly equal distribution between males and females and most often occurs in young adults during the third and fourth decades of life.^4,12-21 Importantly, delayed-type hypersensitivity reactions to mango can manifest as either localized or systemic ACD. Localized ACD can be induced via direct contact with the mango tree and its components or ingestion of the fruit.^3,12,22 Conversely, systemic ACD is primarily stimulated by ingestion of the fruit. In our case, the patient had no history of allergy following mango ingestion, and her ACD was prompted by isolated contact with mango sap. The time from exposure to symptom onset of known instances of mango ACD varies widely, ranging from less than 24 hours to as long as 9 days.^3,12 Diagnosis of mango-induced ACD largely is guided by clinical findings. Presenting symptoms often include an eczematous, vesicular, pruritic rash on affected areas of the skin, frequently the head, neck, and extremities. Patients also commonly present with linear papulovesicular lesions and periorbital or perioral edema.

The suspected allergens responsible for mango-induced ACD are derived from resorcinol—specifically heptadecadienyl resorcinol, heptadecenyl resorcinol, and pentadecyl resorcinol, which are collectively known as mango allergens.²³ These allergens can be found within the pulp and skin of the mango fruit as well as in the bark and leaves of the mango tree, which may explain observed allergic reactions to components of both the mango fruit and tree.¹² Similar to these resorcinol derivatives, the urushiol resin found in poison ivy and poison oak is a catechol derivative.² Importantly, both resorcinols and catechols are isomers of the same aromatic ­phenol—dihydroxybenzene. Because of these similarities, it is thought that the allergens in mangos may cross-react with urushiol in poison ivy or poison oak.²³ Alongside their shared categorization in the Anacardiaceae family, it is hypothesized that this cross-reactivity underlies the sensitization that has been noted between mango and poison ivy or poison oak exposure.^12,23,24 Thus, ACD often can occur on initial contact with the mango tree or its components, as a prior exposure to poison ivy or poison oak may serve as the inciting factor for hypersensitization. The majority of reported cases in the literature also occurred in countries where exposure to poison ivy and poison oak are common, further supporting the notion that these compounds may provide a sensitizing trigger for a future mango contact allergy.¹²

A detailed clinical history combined with adjunctive diagnostic support from patch testing and histopathology of biopsied skin lesions classically are used in the diagnosis of mango-induced ACD. Due to its ability to provide quick and noninvasive in vivo imaging of cutaneous lesions, RCM's applications have expanded to include evaluation of inflammatory skin diseases such as contact dermatitis. Many features of contact dermatitis identified via RCM are common between ACD and irritant contact dermatitis (ICD) and include disruption of the stratum corneum, parakeratosis, vesiculation, spongiosis, and exocytosis.^6,10,25 Studies also have described features shown via RCM that are unique to ACD, including vasodilation and intercellular edema, compared to more distinct targetoid keratinocytes and detached corneocytes seen in ICD.^6,10,25 Studies by Astner et al^5,6 demonstrated a wide range of sensitivity from 52% to 96% and a high specificity of RCM greater than 95% for many of the aforementioned features of contact dermatitis, including disruption of the stratum corneum, parakeratosis, spongiosis, and exocytosis. Additional studies have further strengthened these findings, demonstrating sensitivity and specificity values of 83% and 92% for contact dermatitis under RCM, respectively.²⁶ Importantly, given the similarities and potentially large overlap of features between ACD and ICD identified via RCM as well as findings seen on physical examination and histopathology, an emphasis on clinical correlation is essential when differentiating between these 2 variants of contact dermatitis. Thus, taken in consideration with clinical contexts, RCM has shown potent diagnostic accuracy and great potential to support the evaluation of ACD alongside patch testing and histopathology.

Final Thoughts

Contact allergy to the mango tree and its components is uncommon. We report a unique case of mango sap–induced ACD evaluated and diagnosed via dynamic visualization under RCM. As a noninvasive and reproducible imaging technique with resolutions comparable to histopathologic analysis, RCM is a promising tool that can be used to support the diagnostic evaluation of ACD.

The mango tree (Mangifera indica) produces ­nutrient-dense fruit—known colloquially as the “king of fruits”—that is widely consumed across the world. Native to southern Asia, the mango tree is a member of the Anacardiaceae family, a large family of flowering, fruit-bearing plants.¹ Many members of the Anacardiaceae family, which includes poison ivy and poison oak, are known to produce urushiol, a skin irritant associated with allergic contact dermatitis (ACD).² Interestingly, despite its widespread consumption and categorization in the Anacardiaceae family, allergic reactions to mango are comparatively rare; they occur as either immediate type I hypersensitivity reactions manifesting with rapid-onset symptoms such as urticaria, wheezing, and angioedema, or delayed type IV hypersensitivity reactions manifesting as ACD.³ Although exposure to components of the mango tree has been most characteristically linked to type IV hypersensitivity reactions, there remain fewer than 40 reported cases of mango-induced ACD since it was first described in 1939.⁴

Evaluation of ACD most commonly includes a thorough clinical assessment with diagnostic support from patch testing and histopathologic review following skin biopsy. In recent years, reflectance confocal microscopy (RCM) has shown promising potential to join the ­repertoire of diagnostic tools for ACD by enabling dynamic and high-resolution imaging of contact dermatitis in vivo.^5-10 Reflectance confocal microscopy is a noninvasive optical imaging technique that uses a low-energy diode laser to penetrate the layers of the skin. The resulting reflected light generates images that facilitate visualization of cutaneous structures to the depth of the papillary dermis.¹¹ While it is most commonly used in skin cancer diagnostics, preliminary studies also have shown an emerging role for RCM in the evaluation of eczematous and inflammatory skin disease, including contact dermatitis.^5-10 Herein, we present a unique case of mango sap–induced ACD imaged and diagnosed in real time via RCM.

Case Report

A 39-year-old woman presented to our clinic with a pruritic vesicular eruption on the right leg of 2 weeks’ duration that initially had developed within 7 days of exposure to mango tree sap (Figure 1). The patient reported having experienced similar pruritic eruptions in the past following contact with mango sap while eating mangos but denied any history of reactions from ingestion of the fruit. She also reported a history of robust reactions to poison ivy; however, a timeline specifying the order of first exposure to these irritants was unknown. She denied any personal or family history of atopic conditions.

The affected skin was imaged in real time during clinic using RCM, which showed an inflammatory infiltrate represented by dark spongiotic vesicles containing bright cells (Figure 2). Additional RCM imaging at the level of the stratum spinosum showed dark spongiotic areas with bright inflammatory cells infiltrating the vesicles, which were surrounded by normal skin showing a typical epidermal honeycomb pattern (Figure 3). These findings were diagnostic of ACD secondary to exposure to mango sap. The patient was advised to apply clobetasol cream 0.05% to the affected area. Notable improvement of the rash was noted within 10 days of treatment.

Comment

Exposure to the mango tree and its fruit is a rare cause of ACD, with few reported cases in the literature. The majority of known instances have occurred in non–mango-cultivating countries, largely the United States, although cases also have been reported in Canada, Australia, France, Japan, and Thailand.^3,12 Mango-induced contact allergy follows a roughly equal distribution between males and females and most often occurs in young adults during the third and fourth decades of life.^4,12-21 Importantly, delayed-type hypersensitivity reactions to mango can manifest as either localized or systemic ACD. Localized ACD can be induced via direct contact with the mango tree and its components or ingestion of the fruit.^3,12,22 Conversely, systemic ACD is primarily stimulated by ingestion of the fruit. In our case, the patient had no history of allergy following mango ingestion, and her ACD was prompted by isolated contact with mango sap. The time from exposure to symptom onset of known instances of mango ACD varies widely, ranging from less than 24 hours to as long as 9 days.^3,12 Diagnosis of mango-induced ACD largely is guided by clinical findings. Presenting symptoms often include an eczematous, vesicular, pruritic rash on affected areas of the skin, frequently the head, neck, and extremities. Patients also commonly present with linear papulovesicular lesions and periorbital or perioral edema.

The suspected allergens responsible for mango-induced ACD are derived from resorcinol—specifically heptadecadienyl resorcinol, heptadecenyl resorcinol, and pentadecyl resorcinol, which are collectively known as mango allergens.²³ These allergens can be found within the pulp and skin of the mango fruit as well as in the bark and leaves of the mango tree, which may explain observed allergic reactions to components of both the mango fruit and tree.¹² Similar to these resorcinol derivatives, the urushiol resin found in poison ivy and poison oak is a catechol derivative.² Importantly, both resorcinols and catechols are isomers of the same aromatic ­phenol—dihydroxybenzene. Because of these similarities, it is thought that the allergens in mangos may cross-react with urushiol in poison ivy or poison oak.²³ Alongside their shared categorization in the Anacardiaceae family, it is hypothesized that this cross-reactivity underlies the sensitization that has been noted between mango and poison ivy or poison oak exposure.^12,23,24 Thus, ACD often can occur on initial contact with the mango tree or its components, as a prior exposure to poison ivy or poison oak may serve as the inciting factor for hypersensitization. The majority of reported cases in the literature also occurred in countries where exposure to poison ivy and poison oak are common, further supporting the notion that these compounds may provide a sensitizing trigger for a future mango contact allergy.¹²

A detailed clinical history combined with adjunctive diagnostic support from patch testing and histopathology of biopsied skin lesions classically are used in the diagnosis of mango-induced ACD. Due to its ability to provide quick and noninvasive in vivo imaging of cutaneous lesions, RCM's applications have expanded to include evaluation of inflammatory skin diseases such as contact dermatitis. Many features of contact dermatitis identified via RCM are common between ACD and irritant contact dermatitis (ICD) and include disruption of the stratum corneum, parakeratosis, vesiculation, spongiosis, and exocytosis.^6,10,25 Studies also have described features shown via RCM that are unique to ACD, including vasodilation and intercellular edema, compared to more distinct targetoid keratinocytes and detached corneocytes seen in ICD.^6,10,25 Studies by Astner et al^5,6 demonstrated a wide range of sensitivity from 52% to 96% and a high specificity of RCM greater than 95% for many of the aforementioned features of contact dermatitis, including disruption of the stratum corneum, parakeratosis, spongiosis, and exocytosis. Additional studies have further strengthened these findings, demonstrating sensitivity and specificity values of 83% and 92% for contact dermatitis under RCM, respectively.²⁶ Importantly, given the similarities and potentially large overlap of features between ACD and ICD identified via RCM as well as findings seen on physical examination and histopathology, an emphasis on clinical correlation is essential when differentiating between these 2 variants of contact dermatitis. Thus, taken in consideration with clinical contexts, RCM has shown potent diagnostic accuracy and great potential to support the evaluation of ACD alongside patch testing and histopathology.

Final Thoughts

Contact allergy to the mango tree and its components is uncommon. We report a unique case of mango sap–induced ACD evaluated and diagnosed via dynamic visualization under RCM. As a noninvasive and reproducible imaging technique with resolutions comparable to histopathologic analysis, RCM is a promising tool that can be used to support the diagnostic evaluation of ACD.

The clinical manifestations of snakebites vary based on the species of snake, bite location, and amount and strength of the venom injected. Locally acting toxins in snake venom predominantly consist of enzymes, such as phospholipase A₂, that cause local tissue destruction and can result in pain, swelling, blistering, ecchymosis, and tissue necrosis at the site of the bite within hours to days after the bite.¹ Systemically acting toxins can target a wide variety of tissues and cause severe systemic complications including paralysis, rhabdomyolysis secondary to muscle damage, coagulopathy, sepsis, and cardiorespiratory failure.²

Although pain and swelling following snakebites typically resolve by 1 month after envenomation, copperhead snakes—a type of pit viper—may cause residual symptoms of pain and swelling lasting for a year or more.³ Additional cutaneous manifestations of copperhead snakebites include wound infections at the bite site, such as cellulitis and necrotizing fasciitis. More devastating complications that have been described following snake envenomation include tissue injury of an entire extremity and development of compartment syndrome, which requires urgent fasciotomy to prevent potential loss of the affected limb.⁴

Physicians should be aware of the potential complications of snakebites to properly manage and counsel their patients. We describe a 42-year-old woman with tender, erythematous, subcutaneous nodules persisting for 4 months following a copperhead snakebite. A biopsy confirmed the diagnosis of snakebite-associated erythema nodosum (EN).

Case Report

A 42-year-old woman presented to our clinic with progressive tender, pruritic, deep-seated, erythematous nodules in multiple locations on the legs after sustaining a bite by a copperhead snake on the left foot 4 months prior. The lesions tended to fluctuate in intensity. In the days following the bite, she initially developed painful red bumps on the left foot just proximal to the bite site with associated pain and swelling extending up to just below the left knee. She reported no other notable symptoms such as fever, arthralgia, fatigue, or gastrointestinal tract symptoms. Physical examination revealed bilateral pitting edema, which was worse in the left leg, along with multiple deep, palpable, tender subcutaneous nodules with erythematous surface change (Figure 1).

Workup performed by an outside provider over the previous month included 2 venous duplex ultrasounds of the left leg, which showed no signs of deep vein thrombosis. Additionally, the patient underwent lateral and anteroposterior radiographs of the left foot, tibia, and fibula, which showed no evidence of fracture.

Given the morphology and distribution of the lesions (Figure 2), EN was strongly favored as the cause of the symptoms, and a biopsy confirmed the diagnosis. All immunohistochemical stains including auramine-­rhodamine for acid-fast bacilli, Grocott-Gomori methenamine silver for fungal organisms, and Brown and Brenn were negative. Given the waxing and waning course of the lesions, which suggested an active neutrophilic rather than purely chronic granulomatous phase of EN, the patient was treated with colchicine 0.6 mg twice daily for 1 month.

Causes of EN and Clinical Manifestations

Erythema nodosum is a common form of septal panniculitis that can be precipitated by inflammatory conditions, infection, or medications (commonly oral contraceptive pills) but often is idiopathic.⁵ The acute phase is neutrophilic, with evolution over time to a granulomatous phase. Common etiologies include sarcoidosis; inflammatory bowel disease; and bacterial or fungal infections such as Streptococcus (especially common in children), histoplasmosis, and coccidioidomycosis. The patient was otherwise healthy and was not taking any medications that are known triggers of EN. A PubMed search of articles indexed for MEDLINE in the English-language literature using the terms copperhead snake bite, erythema nodosum snake, and copperhead snake erythema nodosum revealed no reports of EN following a bite from a copperhead snake; however, in one case, an adder bite led to erysipelas, likely due to disturbed blood and lymphatic flow, which then triggered EN.⁶ Additionally, EN has been reported as a delayed reaction to jellyfish stings.⁷

Clinical features of EN include the development of tender, erythematous, subcutaneous nodules and plaques most frequently over the pretibial region. Lesions typically evolve from raised, deep-seated nodules into flat indurated plaques over a span of weeks. Occasionally, there is a slight prodromal phase marked by nonspecific symptoms such as fever and arthralgia lasting for 3 to 6 days. Erythema nodosum typically results in spontaneous resolution after 4 to 8 weeks, and management involves treatment of any underlying condition with symptomatic care. Interestingly, our patient experienced persistent symptoms over the course of 4 months, with development of new nodular lesions throughout this time period. The most frequently used drugs for the management of symptomatic EN include nonsteroidal anti-inflammatory drugs, colchicine, and potassium iodide.⁸ A characteristic histologic finding of the granulomatous phase is the Miescher radial granuloma, which is a septal collection of histiocytes surrounding a cleft.⁹

Snakebite Reactions

Snakebites can result in a wide range of local and systemic manifestations, as snake venom may contain 20 or more toxins.¹⁰ Local complications of pit viper bites include pain, swelling, and fang marks; when examining fang marks, the presence of 2 distinct puncture wounds often indicates envenomation with a poisonous snake, whereas nonvenomous snakebites often result in smaller puncture wounds arranged in an arc. Following bites, pain can develop immediately and spread proximally up the affected limb, which occurred in our patient in the days following the bite. Intense local reactions can occur, as bites often result in intense edema of the affected limb spreading to the trunk in the days to weeks after the bite, occasionally accompanied by regional lymphadenopathy. Some bites can result in local necrosis and secondary bacterial infection caused by organisms in the oral cavity of the culprit snake.

Although they were not present in our patient, snakebites can result in a wide range of systemic toxicities ranging from clotting defects and hemolysis to neurotoxicity, myotoxicity, and nephrotoxicity.¹⁰ In severe cases, snake venom can result in disseminated intravascular coagulation, sepsis, and cardiorespiratory collapse.

The eastern copperhead (Agkistrodon contortrix) is a species of venomous snake that is endemic to eastern North America. Copperheads are members of the subfamily Crotalinae in the family Viperidae.¹¹ Reported reactions to copperhead bites include cellulitis, necrotizing fasciitis, compartment syndrome, and tissue necrosis of an entire affected extremity.^12,13 Our patient displayed no systemic symptoms to suggest envenomation.

Management of Snakebites

Treatment of snakebites varies based on the constellation and severity of symptoms as well as how recently the envenomation occurred. In urgent cases, antivenom may be administered to prevent further toxicity. In cases of progressive compartment syndrome, emergent surgical procedures such as fasciotomy or amputation are required to prevent further complications. When a superimposed bacterial infection is suspected, broad-spectrum antibiotics are required. Because our patient presented 4 months following the initial bite with isolated cutaneous manifestations, she was treated symptomatically with colchicine for EN.^1,2

Final Thoughts

Our patient presented with EN following a bite from a copperhead snake. Physicians should be aware of possible etiologies of EN to evaluate patients who present with new-onset tender subcutaneous nodules. Additionally, physicians should be aware of venomous snakes endemic to their region and also understand the various complications that can result following a snakebite, with the potential for lingering cutaneous manifestations weeks to months following the initial bite.

The clinical manifestations of snakebites vary based on the species of snake, bite location, and amount and strength of the venom injected. Locally acting toxins in snake venom predominantly consist of enzymes, such as phospholipase A₂, that cause local tissue destruction and can result in pain, swelling, blistering, ecchymosis, and tissue necrosis at the site of the bite within hours to days after the bite.¹ Systemically acting toxins can target a wide variety of tissues and cause severe systemic complications including paralysis, rhabdomyolysis secondary to muscle damage, coagulopathy, sepsis, and cardiorespiratory failure.²

Although pain and swelling following snakebites typically resolve by 1 month after envenomation, copperhead snakes—a type of pit viper—may cause residual symptoms of pain and swelling lasting for a year or more.³ Additional cutaneous manifestations of copperhead snakebites include wound infections at the bite site, such as cellulitis and necrotizing fasciitis. More devastating complications that have been described following snake envenomation include tissue injury of an entire extremity and development of compartment syndrome, which requires urgent fasciotomy to prevent potential loss of the affected limb.⁴

Physicians should be aware of the potential complications of snakebites to properly manage and counsel their patients. We describe a 42-year-old woman with tender, erythematous, subcutaneous nodules persisting for 4 months following a copperhead snakebite. A biopsy confirmed the diagnosis of snakebite-associated erythema nodosum (EN).

Case Report

A 42-year-old woman presented to our clinic with progressive tender, pruritic, deep-seated, erythematous nodules in multiple locations on the legs after sustaining a bite by a copperhead snake on the left foot 4 months prior. The lesions tended to fluctuate in intensity. In the days following the bite, she initially developed painful red bumps on the left foot just proximal to the bite site with associated pain and swelling extending up to just below the left knee. She reported no other notable symptoms such as fever, arthralgia, fatigue, or gastrointestinal tract symptoms. Physical examination revealed bilateral pitting edema, which was worse in the left leg, along with multiple deep, palpable, tender subcutaneous nodules with erythematous surface change (Figure 1).

Workup performed by an outside provider over the previous month included 2 venous duplex ultrasounds of the left leg, which showed no signs of deep vein thrombosis. Additionally, the patient underwent lateral and anteroposterior radiographs of the left foot, tibia, and fibula, which showed no evidence of fracture.

Given the morphology and distribution of the lesions (Figure 2), EN was strongly favored as the cause of the symptoms, and a biopsy confirmed the diagnosis. All immunohistochemical stains including auramine-­rhodamine for acid-fast bacilli, Grocott-Gomori methenamine silver for fungal organisms, and Brown and Brenn were negative. Given the waxing and waning course of the lesions, which suggested an active neutrophilic rather than purely chronic granulomatous phase of EN, the patient was treated with colchicine 0.6 mg twice daily for 1 month.

Causes of EN and Clinical Manifestations

Erythema nodosum is a common form of septal panniculitis that can be precipitated by inflammatory conditions, infection, or medications (commonly oral contraceptive pills) but often is idiopathic.⁵ The acute phase is neutrophilic, with evolution over time to a granulomatous phase. Common etiologies include sarcoidosis; inflammatory bowel disease; and bacterial or fungal infections such as Streptococcus (especially common in children), histoplasmosis, and coccidioidomycosis. The patient was otherwise healthy and was not taking any medications that are known triggers of EN. A PubMed search of articles indexed for MEDLINE in the English-language literature using the terms copperhead snake bite, erythema nodosum snake, and copperhead snake erythema nodosum revealed no reports of EN following a bite from a copperhead snake; however, in one case, an adder bite led to erysipelas, likely due to disturbed blood and lymphatic flow, which then triggered EN.⁶ Additionally, EN has been reported as a delayed reaction to jellyfish stings.⁷

Clinical features of EN include the development of tender, erythematous, subcutaneous nodules and plaques most frequently over the pretibial region. Lesions typically evolve from raised, deep-seated nodules into flat indurated plaques over a span of weeks. Occasionally, there is a slight prodromal phase marked by nonspecific symptoms such as fever and arthralgia lasting for 3 to 6 days. Erythema nodosum typically results in spontaneous resolution after 4 to 8 weeks, and management involves treatment of any underlying condition with symptomatic care. Interestingly, our patient experienced persistent symptoms over the course of 4 months, with development of new nodular lesions throughout this time period. The most frequently used drugs for the management of symptomatic EN include nonsteroidal anti-inflammatory drugs, colchicine, and potassium iodide.⁸ A characteristic histologic finding of the granulomatous phase is the Miescher radial granuloma, which is a septal collection of histiocytes surrounding a cleft.⁹

Snakebite Reactions

Snakebites can result in a wide range of local and systemic manifestations, as snake venom may contain 20 or more toxins.¹⁰ Local complications of pit viper bites include pain, swelling, and fang marks; when examining fang marks, the presence of 2 distinct puncture wounds often indicates envenomation with a poisonous snake, whereas nonvenomous snakebites often result in smaller puncture wounds arranged in an arc. Following bites, pain can develop immediately and spread proximally up the affected limb, which occurred in our patient in the days following the bite. Intense local reactions can occur, as bites often result in intense edema of the affected limb spreading to the trunk in the days to weeks after the bite, occasionally accompanied by regional lymphadenopathy. Some bites can result in local necrosis and secondary bacterial infection caused by organisms in the oral cavity of the culprit snake.

Although they were not present in our patient, snakebites can result in a wide range of systemic toxicities ranging from clotting defects and hemolysis to neurotoxicity, myotoxicity, and nephrotoxicity.¹⁰ In severe cases, snake venom can result in disseminated intravascular coagulation, sepsis, and cardiorespiratory collapse.

The eastern copperhead (Agkistrodon contortrix) is a species of venomous snake that is endemic to eastern North America. Copperheads are members of the subfamily Crotalinae in the family Viperidae.¹¹ Reported reactions to copperhead bites include cellulitis, necrotizing fasciitis, compartment syndrome, and tissue necrosis of an entire affected extremity.^12,13 Our patient displayed no systemic symptoms to suggest envenomation.

Management of Snakebites

Treatment of snakebites varies based on the constellation and severity of symptoms as well as how recently the envenomation occurred. In urgent cases, antivenom may be administered to prevent further toxicity. In cases of progressive compartment syndrome, emergent surgical procedures such as fasciotomy or amputation are required to prevent further complications. When a superimposed bacterial infection is suspected, broad-spectrum antibiotics are required. Because our patient presented 4 months following the initial bite with isolated cutaneous manifestations, she was treated symptomatically with colchicine for EN.^1,2

Final Thoughts

Our patient presented with EN following a bite from a copperhead snake. Physicians should be aware of possible etiologies of EN to evaluate patients who present with new-onset tender subcutaneous nodules. Additionally, physicians should be aware of venomous snakes endemic to their region and also understand the various complications that can result following a snakebite, with the potential for lingering cutaneous manifestations weeks to months following the initial bite.

The clinical manifestations of snakebites vary based on the species of snake, bite location, and amount and strength of the venom injected. Locally acting toxins in snake venom predominantly consist of enzymes, such as phospholipase A₂, that cause local tissue destruction and can result in pain, swelling, blistering, ecchymosis, and tissue necrosis at the site of the bite within hours to days after the bite.¹ Systemically acting toxins can target a wide variety of tissues and cause severe systemic complications including paralysis, rhabdomyolysis secondary to muscle damage, coagulopathy, sepsis, and cardiorespiratory failure.²

Although pain and swelling following snakebites typically resolve by 1 month after envenomation, copperhead snakes—a type of pit viper—may cause residual symptoms of pain and swelling lasting for a year or more.³ Additional cutaneous manifestations of copperhead snakebites include wound infections at the bite site, such as cellulitis and necrotizing fasciitis. More devastating complications that have been described following snake envenomation include tissue injury of an entire extremity and development of compartment syndrome, which requires urgent fasciotomy to prevent potential loss of the affected limb.⁴

Physicians should be aware of the potential complications of snakebites to properly manage and counsel their patients. We describe a 42-year-old woman with tender, erythematous, subcutaneous nodules persisting for 4 months following a copperhead snakebite. A biopsy confirmed the diagnosis of snakebite-associated erythema nodosum (EN).

Case Report

A 42-year-old woman presented to our clinic with progressive tender, pruritic, deep-seated, erythematous nodules in multiple locations on the legs after sustaining a bite by a copperhead snake on the left foot 4 months prior. The lesions tended to fluctuate in intensity. In the days following the bite, she initially developed painful red bumps on the left foot just proximal to the bite site with associated pain and swelling extending up to just below the left knee. She reported no other notable symptoms such as fever, arthralgia, fatigue, or gastrointestinal tract symptoms. Physical examination revealed bilateral pitting edema, which was worse in the left leg, along with multiple deep, palpable, tender subcutaneous nodules with erythematous surface change (Figure 1).

Workup performed by an outside provider over the previous month included 2 venous duplex ultrasounds of the left leg, which showed no signs of deep vein thrombosis. Additionally, the patient underwent lateral and anteroposterior radiographs of the left foot, tibia, and fibula, which showed no evidence of fracture.

Given the morphology and distribution of the lesions (Figure 2), EN was strongly favored as the cause of the symptoms, and a biopsy confirmed the diagnosis. All immunohistochemical stains including auramine-­rhodamine for acid-fast bacilli, Grocott-Gomori methenamine silver for fungal organisms, and Brown and Brenn were negative. Given the waxing and waning course of the lesions, which suggested an active neutrophilic rather than purely chronic granulomatous phase of EN, the patient was treated with colchicine 0.6 mg twice daily for 1 month.

Causes of EN and Clinical Manifestations

Erythema nodosum is a common form of septal panniculitis that can be precipitated by inflammatory conditions, infection, or medications (commonly oral contraceptive pills) but often is idiopathic.⁵ The acute phase is neutrophilic, with evolution over time to a granulomatous phase. Common etiologies include sarcoidosis; inflammatory bowel disease; and bacterial or fungal infections such as Streptococcus (especially common in children), histoplasmosis, and coccidioidomycosis. The patient was otherwise healthy and was not taking any medications that are known triggers of EN. A PubMed search of articles indexed for MEDLINE in the English-language literature using the terms copperhead snake bite, erythema nodosum snake, and copperhead snake erythema nodosum revealed no reports of EN following a bite from a copperhead snake; however, in one case, an adder bite led to erysipelas, likely due to disturbed blood and lymphatic flow, which then triggered EN.⁶ Additionally, EN has been reported as a delayed reaction to jellyfish stings.⁷

Clinical features of EN include the development of tender, erythematous, subcutaneous nodules and plaques most frequently over the pretibial region. Lesions typically evolve from raised, deep-seated nodules into flat indurated plaques over a span of weeks. Occasionally, there is a slight prodromal phase marked by nonspecific symptoms such as fever and arthralgia lasting for 3 to 6 days. Erythema nodosum typically results in spontaneous resolution after 4 to 8 weeks, and management involves treatment of any underlying condition with symptomatic care. Interestingly, our patient experienced persistent symptoms over the course of 4 months, with development of new nodular lesions throughout this time period. The most frequently used drugs for the management of symptomatic EN include nonsteroidal anti-inflammatory drugs, colchicine, and potassium iodide.⁸ A characteristic histologic finding of the granulomatous phase is the Miescher radial granuloma, which is a septal collection of histiocytes surrounding a cleft.⁹

Snakebite Reactions

Snakebites can result in a wide range of local and systemic manifestations, as snake venom may contain 20 or more toxins.¹⁰ Local complications of pit viper bites include pain, swelling, and fang marks; when examining fang marks, the presence of 2 distinct puncture wounds often indicates envenomation with a poisonous snake, whereas nonvenomous snakebites often result in smaller puncture wounds arranged in an arc. Following bites, pain can develop immediately and spread proximally up the affected limb, which occurred in our patient in the days following the bite. Intense local reactions can occur, as bites often result in intense edema of the affected limb spreading to the trunk in the days to weeks after the bite, occasionally accompanied by regional lymphadenopathy. Some bites can result in local necrosis and secondary bacterial infection caused by organisms in the oral cavity of the culprit snake.

Although they were not present in our patient, snakebites can result in a wide range of systemic toxicities ranging from clotting defects and hemolysis to neurotoxicity, myotoxicity, and nephrotoxicity.¹⁰ In severe cases, snake venom can result in disseminated intravascular coagulation, sepsis, and cardiorespiratory collapse.

The eastern copperhead (Agkistrodon contortrix) is a species of venomous snake that is endemic to eastern North America. Copperheads are members of the subfamily Crotalinae in the family Viperidae.¹¹ Reported reactions to copperhead bites include cellulitis, necrotizing fasciitis, compartment syndrome, and tissue necrosis of an entire affected extremity.^12,13 Our patient displayed no systemic symptoms to suggest envenomation.

Management of Snakebites

Treatment of snakebites varies based on the constellation and severity of symptoms as well as how recently the envenomation occurred. In urgent cases, antivenom may be administered to prevent further toxicity. In cases of progressive compartment syndrome, emergent surgical procedures such as fasciotomy or amputation are required to prevent further complications. When a superimposed bacterial infection is suspected, broad-spectrum antibiotics are required. Because our patient presented 4 months following the initial bite with isolated cutaneous manifestations, she was treated symptomatically with colchicine for EN.^1,2

Final Thoughts

Our patient presented with EN following a bite from a copperhead snake. Physicians should be aware of possible etiologies of EN to evaluate patients who present with new-onset tender subcutaneous nodules. Additionally, physicians should be aware of venomous snakes endemic to their region and also understand the various complications that can result following a snakebite, with the potential for lingering cutaneous manifestations weeks to months following the initial bite.

Brazilian peppertree (Schinus terebinthifolia), a member of the Anacardiaceae family, is an internationally invasive plant that causes allergic contact dermatitis (ACD) in susceptible individuals. This noxious weed has settled into the landscape of the southern United States and continues to expand. Its key identifying features include its year-round white flowers as well as a peppery and turpentinelike aroma created by cracking its bright red berries. The ACD associated with contact—primarily with the plant’s sap—stems from known alkenyl phenols, cardol and cardanol. Treatment of Brazilian peppertree–associated ACD parallels that for poison ivy. As this pest increases its range, dermatologists living in endemic areas should familiarize themselves with Brazilian peppertree and its potential for harm.

Brazilian Peppertree Morphology and Geography

Plants in the Anacardiaceae family contribute to more ACD than any other family, and its 80 genera include most of the urushiol-containing plants, such as Toxicodendron (poison ivy, poison oak, poison sumac, Japanese lacquer tree), Anacardium (cashew tree), Mangifera (mango fruit), Semecarpus (India marking nut tree), and Schinus (Brazilian peppertree). Deciduous and evergreen tree members of the Anacardiaceae family grow primarily in tropical and subtropical locations and produce thick resins, 5-petalled flowers, and small fruit known as drupes. The genus name for Brazilian peppertree, Schinus, derives from Latin and Greek words meaning “mastic tree,” a relative of the pistachio tree that the Brazilian peppertree resembles.¹ Brazilian peppertree leaves look and smell similar to Pistacia terebinthus (turpentine tree or terebinth), from which the species name terebinthifolia derives.²

Brazilian peppertree originated in South America, particularly Brazil, Paraguay, and Argentina.³ Since the 1840s,⁴ it has been an invasive weed in the United States, notably in Florida, California, Hawaii, Alabama, Georgia,⁵ Arizona,⁶ Nevada,³ and Texas.^5,7 The plant also grows throughout the world, including parts of Africa, Asia, Central America, Europe,⁶ New Zealand,⁸ Australia, and various islands.⁹ The plant expertly outcompetes neighboring plants and has prompted control and eradication efforts in many locations.³

Identifying Features and Allergenic Plant Parts

Brazilian peppertree can be either a shrub or tree up to 30 feet tall.⁴ As an evergreen, it retains its leaves year-round. During fruiting seasons (primarily December through March⁷), bright red or pink (depending on the variety³) berries appear (Figure 1A) and contribute to its nickname “Florida holly.” Although generally considered an unwelcome guest in Florida, it does display white flowers (Figure 1B) year-round, especially from September to November.⁹ It characteristically exhibits 3 to 13 leaflets per leaf.¹⁰ The leaflets’ ovoid and ridged edges, netlike vasculature, shiny hue, and aroma can help identify the plant (Figure 2A). For decades, the sap of the Brazilian peppertree has been associated with skin ­irritation (Figure 2B).⁶ Although the sap of the plant serves as the main culprit of Brazilian peppertree–­associated ACD, it appears that other parts of the plant, including the fruit, can cause irritating effects to skin on contact.^11,12 The leaves, trunk, and fruit can be harmful to both humans and animals.⁶ Chemicals from flowers and crushed fruit also can lead to irritating effects in the respiratory tract if aspirated.¹³

Urushiol, an oily resin present in most plants of the Anacardiaceae family,¹⁴ contains many chemicals, including allergenic phenols, catechols, and resorcinols.¹⁵ Urushiol-allergic individuals develop dermatitis upon exposure to Brazilian peppertree sap.⁶ Alkenyl phenols found in Brazilian peppertree lead to the cutaneous manifestations in sensitized patients.^11,12 In 1983, Stahl et al¹¹ identified a phenol, cardanol (chemical name ­3-pentadecylphenol¹⁶) C15:1, in Brazilian peppertree fruit. The group further tested this compound’s effect on skin via patch testing, which showed an allergic response.¹¹ Cashew nut shells (Anacardium occidentale) contain cardanol, anacardic acid (a phenolic acid), and cardol (a phenol with the chemical name ­5-pentadecylresorcinol),^15,16 though Stahl et al¹¹ were unable to extract these 2 substances (if present) from Brazilian peppertree fruit. When exposed to cardol and anacardic acid, those allergic to poison ivy often develop ACD,¹⁵ and these 2 substances are more irritating than cardanol.¹¹ A later study did identify cardol in addition to cardanol in Brazilian peppertree.¹²

Cutaneous Manifestations

Brazilian peppertree–induced ACD appears similar to other plant-induced ACD with linear streaks of erythema, juicy papules, vesicles, coalescing erythematous plaques, and/or occasional edema and bullae accompanied by intense pruritus.

Treatment

Avoiding contact with Brazilian peppertree is the first line of defense, and treatment for a reaction associated with exposure is similar to that of poison ivy.¹⁷ Application of cool compresses, calamine lotion, and topical astringents offer symptom alleviation, and topical steroids (eg, clobetasol propionate 0.05% twice daily) can improve mild localized ACD when given prior to formation of blisters. For more severe and diffuse ACD, oral steroids (eg, prednisone 1 mg/kg/d tapered over 2–3 weeks) likely are necessary, though intramuscular options greatly alleviate discomfort in more severe cases (eg, intramuscular triamcinolone acetonide 1 mg/kg combined with betamethasone 0.1 mg/kg). Physicians should monitor sites for any signs of superimposed bacterial infection and initiate antibiotics as necessary.¹⁷

Brazilian peppertree (Schinus terebinthifolia), a member of the Anacardiaceae family, is an internationally invasive plant that causes allergic contact dermatitis (ACD) in susceptible individuals. This noxious weed has settled into the landscape of the southern United States and continues to expand. Its key identifying features include its year-round white flowers as well as a peppery and turpentinelike aroma created by cracking its bright red berries. The ACD associated with contact—primarily with the plant’s sap—stems from known alkenyl phenols, cardol and cardanol. Treatment of Brazilian peppertree–associated ACD parallels that for poison ivy. As this pest increases its range, dermatologists living in endemic areas should familiarize themselves with Brazilian peppertree and its potential for harm.

Brazilian Peppertree Morphology and Geography

Plants in the Anacardiaceae family contribute to more ACD than any other family, and its 80 genera include most of the urushiol-containing plants, such as Toxicodendron (poison ivy, poison oak, poison sumac, Japanese lacquer tree), Anacardium (cashew tree), Mangifera (mango fruit), Semecarpus (India marking nut tree), and Schinus (Brazilian peppertree). Deciduous and evergreen tree members of the Anacardiaceae family grow primarily in tropical and subtropical locations and produce thick resins, 5-petalled flowers, and small fruit known as drupes. The genus name for Brazilian peppertree, Schinus, derives from Latin and Greek words meaning “mastic tree,” a relative of the pistachio tree that the Brazilian peppertree resembles.¹ Brazilian peppertree leaves look and smell similar to Pistacia terebinthus (turpentine tree or terebinth), from which the species name terebinthifolia derives.²

Brazilian peppertree originated in South America, particularly Brazil, Paraguay, and Argentina.³ Since the 1840s,⁴ it has been an invasive weed in the United States, notably in Florida, California, Hawaii, Alabama, Georgia,⁵ Arizona,⁶ Nevada,³ and Texas.^5,7 The plant also grows throughout the world, including parts of Africa, Asia, Central America, Europe,⁶ New Zealand,⁸ Australia, and various islands.⁹ The plant expertly outcompetes neighboring plants and has prompted control and eradication efforts in many locations.³

Identifying Features and Allergenic Plant Parts

Brazilian peppertree can be either a shrub or tree up to 30 feet tall.⁴ As an evergreen, it retains its leaves year-round. During fruiting seasons (primarily December through March⁷), bright red or pink (depending on the variety³) berries appear (Figure 1A) and contribute to its nickname “Florida holly.” Although generally considered an unwelcome guest in Florida, it does display white flowers (Figure 1B) year-round, especially from September to November.⁹ It characteristically exhibits 3 to 13 leaflets per leaf.¹⁰ The leaflets’ ovoid and ridged edges, netlike vasculature, shiny hue, and aroma can help identify the plant (Figure 2A). For decades, the sap of the Brazilian peppertree has been associated with skin ­irritation (Figure 2B).⁶ Although the sap of the plant serves as the main culprit of Brazilian peppertree–­associated ACD, it appears that other parts of the plant, including the fruit, can cause irritating effects to skin on contact.^11,12 The leaves, trunk, and fruit can be harmful to both humans and animals.⁶ Chemicals from flowers and crushed fruit also can lead to irritating effects in the respiratory tract if aspirated.¹³

Urushiol, an oily resin present in most plants of the Anacardiaceae family,¹⁴ contains many chemicals, including allergenic phenols, catechols, and resorcinols.¹⁵ Urushiol-allergic individuals develop dermatitis upon exposure to Brazilian peppertree sap.⁶ Alkenyl phenols found in Brazilian peppertree lead to the cutaneous manifestations in sensitized patients.^11,12 In 1983, Stahl et al¹¹ identified a phenol, cardanol (chemical name ­3-pentadecylphenol¹⁶) C15:1, in Brazilian peppertree fruit. The group further tested this compound’s effect on skin via patch testing, which showed an allergic response.¹¹ Cashew nut shells (Anacardium occidentale) contain cardanol, anacardic acid (a phenolic acid), and cardol (a phenol with the chemical name ­5-pentadecylresorcinol),^15,16 though Stahl et al¹¹ were unable to extract these 2 substances (if present) from Brazilian peppertree fruit. When exposed to cardol and anacardic acid, those allergic to poison ivy often develop ACD,¹⁵ and these 2 substances are more irritating than cardanol.¹¹ A later study did identify cardol in addition to cardanol in Brazilian peppertree.¹²

Cutaneous Manifestations

Brazilian peppertree–induced ACD appears similar to other plant-induced ACD with linear streaks of erythema, juicy papules, vesicles, coalescing erythematous plaques, and/or occasional edema and bullae accompanied by intense pruritus.

Treatment

Avoiding contact with Brazilian peppertree is the first line of defense, and treatment for a reaction associated with exposure is similar to that of poison ivy.¹⁷ Application of cool compresses, calamine lotion, and topical astringents offer symptom alleviation, and topical steroids (eg, clobetasol propionate 0.05% twice daily) can improve mild localized ACD when given prior to formation of blisters. For more severe and diffuse ACD, oral steroids (eg, prednisone 1 mg/kg/d tapered over 2–3 weeks) likely are necessary, though intramuscular options greatly alleviate discomfort in more severe cases (eg, intramuscular triamcinolone acetonide 1 mg/kg combined with betamethasone 0.1 mg/kg). Physicians should monitor sites for any signs of superimposed bacterial infection and initiate antibiotics as necessary.¹⁷

Brazilian peppertree (Schinus terebinthifolia), a member of the Anacardiaceae family, is an internationally invasive plant that causes allergic contact dermatitis (ACD) in susceptible individuals. This noxious weed has settled into the landscape of the southern United States and continues to expand. Its key identifying features include its year-round white flowers as well as a peppery and turpentinelike aroma created by cracking its bright red berries. The ACD associated with contact—primarily with the plant’s sap—stems from known alkenyl phenols, cardol and cardanol. Treatment of Brazilian peppertree–associated ACD parallels that for poison ivy. As this pest increases its range, dermatologists living in endemic areas should familiarize themselves with Brazilian peppertree and its potential for harm.

Brazilian Peppertree Morphology and Geography

Plants in the Anacardiaceae family contribute to more ACD than any other family, and its 80 genera include most of the urushiol-containing plants, such as Toxicodendron (poison ivy, poison oak, poison sumac, Japanese lacquer tree), Anacardium (cashew tree), Mangifera (mango fruit), Semecarpus (India marking nut tree), and Schinus (Brazilian peppertree). Deciduous and evergreen tree members of the Anacardiaceae family grow primarily in tropical and subtropical locations and produce thick resins, 5-petalled flowers, and small fruit known as drupes. The genus name for Brazilian peppertree, Schinus, derives from Latin and Greek words meaning “mastic tree,” a relative of the pistachio tree that the Brazilian peppertree resembles.¹ Brazilian peppertree leaves look and smell similar to Pistacia terebinthus (turpentine tree or terebinth), from which the species name terebinthifolia derives.²

Brazilian peppertree originated in South America, particularly Brazil, Paraguay, and Argentina.³ Since the 1840s,⁴ it has been an invasive weed in the United States, notably in Florida, California, Hawaii, Alabama, Georgia,⁵ Arizona,⁶ Nevada,³ and Texas.^5,7 The plant also grows throughout the world, including parts of Africa, Asia, Central America, Europe,⁶ New Zealand,⁸ Australia, and various islands.⁹ The plant expertly outcompetes neighboring plants and has prompted control and eradication efforts in many locations.³

Identifying Features and Allergenic Plant Parts

Brazilian peppertree can be either a shrub or tree up to 30 feet tall.⁴ As an evergreen, it retains its leaves year-round. During fruiting seasons (primarily December through March⁷), bright red or pink (depending on the variety³) berries appear (Figure 1A) and contribute to its nickname “Florida holly.” Although generally considered an unwelcome guest in Florida, it does display white flowers (Figure 1B) year-round, especially from September to November.⁹ It characteristically exhibits 3 to 13 leaflets per leaf.¹⁰ The leaflets’ ovoid and ridged edges, netlike vasculature, shiny hue, and aroma can help identify the plant (Figure 2A). For decades, the sap of the Brazilian peppertree has been associated with skin ­irritation (Figure 2B).⁶ Although the sap of the plant serves as the main culprit of Brazilian peppertree–­associated ACD, it appears that other parts of the plant, including the fruit, can cause irritating effects to skin on contact.^11,12 The leaves, trunk, and fruit can be harmful to both humans and animals.⁶ Chemicals from flowers and crushed fruit also can lead to irritating effects in the respiratory tract if aspirated.¹³

Urushiol, an oily resin present in most plants of the Anacardiaceae family,¹⁴ contains many chemicals, including allergenic phenols, catechols, and resorcinols.¹⁵ Urushiol-allergic individuals develop dermatitis upon exposure to Brazilian peppertree sap.⁶ Alkenyl phenols found in Brazilian peppertree lead to the cutaneous manifestations in sensitized patients.^11,12 In 1983, Stahl et al¹¹ identified a phenol, cardanol (chemical name ­3-pentadecylphenol¹⁶) C15:1, in Brazilian peppertree fruit. The group further tested this compound’s effect on skin via patch testing, which showed an allergic response.¹¹ Cashew nut shells (Anacardium occidentale) contain cardanol, anacardic acid (a phenolic acid), and cardol (a phenol with the chemical name ­5-pentadecylresorcinol),^15,16 though Stahl et al¹¹ were unable to extract these 2 substances (if present) from Brazilian peppertree fruit. When exposed to cardol and anacardic acid, those allergic to poison ivy often develop ACD,¹⁵ and these 2 substances are more irritating than cardanol.¹¹ A later study did identify cardol in addition to cardanol in Brazilian peppertree.¹²

Cutaneous Manifestations

Brazilian peppertree–induced ACD appears similar to other plant-induced ACD with linear streaks of erythema, juicy papules, vesicles, coalescing erythematous plaques, and/or occasional edema and bullae accompanied by intense pruritus.

Treatment

Avoiding contact with Brazilian peppertree is the first line of defense, and treatment for a reaction associated with exposure is similar to that of poison ivy.¹⁷ Application of cool compresses, calamine lotion, and topical astringents offer symptom alleviation, and topical steroids (eg, clobetasol propionate 0.05% twice daily) can improve mild localized ACD when given prior to formation of blisters. For more severe and diffuse ACD, oral steroids (eg, prednisone 1 mg/kg/d tapered over 2–3 weeks) likely are necessary, though intramuscular options greatly alleviate discomfort in more severe cases (eg, intramuscular triamcinolone acetonide 1 mg/kg combined with betamethasone 0.1 mg/kg). Physicians should monitor sites for any signs of superimposed bacterial infection and initiate antibiotics as necessary.¹⁷

Sea urchins—members of the phylum Echinodermata and the class Echinoidea—are spiny marine invertebrates. Their consumption of fleshy algae makes them essential players in maintaining reef ecosystems.^1,2 Echinoids, a class that includes heart urchins and sand dollars, are ubiquitous in benthic marine environments, both free floating and rock boring, and inhabit a wide range of latitudes spanning from polar oceans to warm seas.³ Despite their immobility and nonaggression, sea urchin puncture wounds are common among divers, snorkelers, swimmers, surfers, and fishers who accidentally come into contact with their sharp spines. Although the epidemiology of sea urchin exposure and injury is difficult to assess, the American Association of Poison Control Centers’ most recent annual report in 2022 documents approximately 1426 annual aquatic bites and/or envenomations.⁴

Sea Urchin Morphology and Toxicity

Echinoderms (a term of Greek origin meaning spiny skin) share a radially symmetric calcium carbonate skeleton (termed stereom) that is supported by collagenous ligaments.¹ Sea urchins possess spines composed of calcite crystals, which radiate from their body and play a role in locomotion and defense against predators—namely sea otters, starfish/sea stars, wolf eels, and triggerfish, among others (Figure).⁵ These brittle spines can easily penetrate human skin and subsequently break off the sea urchin body. Most species of sea urchins possess solid spines, but a small percentage (80 of approximately 700 extant species) have hollow spines containing various toxic substances.⁶ Penetration and systemic absorption of the toxins within these spines can generate severe systemic responses.

The venomous flower urchin (Toxopneustes pileolus), found in the Indian and Pacific oceans, is one of the more common species known to produce a systemic reaction involving neuromuscular blockage.^7-9 The most common species harvested off the Pacific coast of the United States—Strongylocentrotus purpuratus (purple sea urchin) and Strongylocentrotus franciscanus (red sea urchins)—are not inherently venomous.⁸

Presentation and Diagnosis of Sea Urchin Injuries

Sea urchin injuries have a wide range of manifestations depending on the number of spines involved, the presence of venom, the depth and location of spine penetration, the duration of spine retention in the skin, and the time before treatment initiation. The most common site of sea urchin injury unsurprisingly is the lower extremities and feet, often in the context of divers and swimmers walking across the sea floor. The hands are another frequently injured site, along with the legs, arms, back, scalp, and even oral mucosa.¹¹

Although clinical history and presentation frequently reveal the mechanism of aquatic injury, patients often are unsure of the agent to which they were exposed and may be unaware of retained foreign bodies. Dermoscopy can distinguish the distinct lines radiating from the core of sea urchin spines from other foreign bodies lodged within the skin.⁶ It also can be used to locate spines for removal or for their analysis following punch biopsy.^6,12 The radiopaque nature of sea urchin spines makes radiography and magnetic resonance imaging useful tools in assessment of periarticular soft-tissue damage and spine removal.^8,11,13 Ultrasonography can reveal spines that no longer appear on radiography due to absorption by human tissue.¹⁴

Immediate Dermatologic Effects

Sea urchin injuries can be broadly categorized into immediate and delayed reactions. Immediate manifestations of contact with sea urchin spines include localized pain, bleeding, erythema, myalgia, and edema at the site of injury that can last from a few hours to 1 week without proper wound care and spine removal.⁵ Systemic symptoms ranging from dizziness, lightheadedness, paresthesia, aphonia, paralysis, coma, and death generally are only seen following injuries from venomous species, attachment of pedicellariae, injuries involving neurovascular structures, or penetration by more than 15 spines.^7,11

Initial treatment includes soaking the wound in hot water (113 °F [45 °C]) for 30 to 90 minutes and subsequently removing spines and pedicellariae to prevent development of delayed reactions.^5,15,16 The compounds in the sea urchin epithelium are heat labile and will be inactivated upon soaking in hot water.¹⁶ Extraction of spines can be difficult, as they are brittle and easily break in the skin. Successful removal has been reported using forceps and a hypodermic needle as well as excision; both approaches may require local anesthesia.^8,17 Another technique involves freezing the localized area with liquid nitrogen to allow easier removal upon skin blistering.¹⁸ Punch biopsy also has been utilized as an effective means of ensuring all spiny fragments are removed.^9,19,20 These spines often cause black or purple tattoolike staining at the puncture site, which can persist for a few days after spine extraction.⁸ Ablation using the erbium-doped:YAG laser may be helpful for removal of associated pigment.^21,22

Delayed Dermatologic Effects

Delayed reactions to sea urchin injuries often are attributable to prolonged retention of spines in the skin. Granulomatous reactions typically manifest 2 weeks after injury as firm nonsuppurative nodules with central umbilication and a hyperkeratotic surface.⁷ These nodules may or may not be painful. Histopathology most often reveals foreign body and sarcoidal-type granulomatous reactions. However, tuberculoid, necrobiotic, and suppurative granulomas also may develop.¹³ Other microscopic features include inflammatory reactions, suppurative dermatitis, focal necrosis, and microabscesses.²³ Wounds with progression to granulomatous disease often require surgical debridement.

Other more serious sequalae can result from involvement of joint capsules, especially in the hands and feet. Sea urchin injury involving joint spaces should be treated aggressively, as progression to inflammatory or infectious synovitis and tenosynovitis can cause irreversible loss of joint function. Inflammatory synovitis occurs 1 to 2 months on average after injury following a period of minimal symptoms and begins as a gradual increase in joint swelling and decrease in range of motion.⁸ Infectious tenosynovitis manifests quite similarly. Although suppurative etiologies generally progress with a more acute onset, certain infectious organisms (eg, Mycobacterium) take on an indolent course and should not be overlooked as a cause of delayed symptoms.⁸ The Kavanel cardinal signs are a sensitive tool used in the diagnosis of infectious flexor sheath tenosynovitis.^8,24 If suspicion for joint infection is high, emergency referral should be made for debridement and culture-guided antibiotic therapy. Left untreated, infectious tenosynovitis can result in tendon necrosis or rupture, digit necrosis, and systemic infection.²⁴ Patients with joint involvement should be referred to specialty care (eg, hand surgeon), as they often require synovectomy and surgical removal of foreign material.⁸

From 1 month to 1 year after injury, prolonged granulomatous synovitis of the hand may eventually lead to joint destruction known as “sea urchin arthritis.” These patients present with decreased range of motion and numerous nodules on the hand with a hyperkeratotic surface. Radiography reveals joint space narrowing, osteolysis, subchondral sclerosis, and periosteal reaction. Synovectomy and debridement are necessary to prevent irreversible joint damage or the need for arthrodesis and bone grafting.²⁴

Other Treatment Considerations

Other important considerations in the care of sea urchin spine injuries include assessment of tetanus immunization status and administration of necessary prophylaxis as soon as possible, even in delayed presentations (Table).^16,25 Cultures should be taken only if infection is suspected. Prophylactic antibiotics are not recommended unless the patient is immunocompromised or otherwise has impaired wound healing. If a patient presents with systemic symptoms, they should be referred to an emergency care facility for further management.

Final Thoughts

Sea urchin injuries can lead to serious complications if not diagnosed quickly and treated properly. Retention of sea urchin spines in the deep tissues and joint spaces may lead to granulomas, inflammatory and infectious tenosynovitis (including mycobacterial infection), and sea urchin arthritis requiring surgical debridement and possible irreversible joint damage, up to a year after initial injury. Patients should be educated on the possibility of developing these delayed reactions and instructed to seek immediate care. Joint deformities, range-of-motion deficits, and involvement of neurovascular structures should be considered emergent and referred for proper management. Shoes and diving gear offer some protection but are easily penetrable by sharp sea urchin spines. Preventive focus should be aimed at educating patients and providers on the importance of prompt spine removal upon injury. Although dermatologic and systemic manifestations vary widely, a thorough history, physical examination, and appropriate use of imaging modalities can facilitate accurate diagnosis and guide treatment.

Sea urchins—members of the phylum Echinodermata and the class Echinoidea—are spiny marine invertebrates. Their consumption of fleshy algae makes them essential players in maintaining reef ecosystems.^1,2 Echinoids, a class that includes heart urchins and sand dollars, are ubiquitous in benthic marine environments, both free floating and rock boring, and inhabit a wide range of latitudes spanning from polar oceans to warm seas.³ Despite their immobility and nonaggression, sea urchin puncture wounds are common among divers, snorkelers, swimmers, surfers, and fishers who accidentally come into contact with their sharp spines. Although the epidemiology of sea urchin exposure and injury is difficult to assess, the American Association of Poison Control Centers’ most recent annual report in 2022 documents approximately 1426 annual aquatic bites and/or envenomations.⁴

Sea Urchin Morphology and Toxicity

Echinoderms (a term of Greek origin meaning spiny skin) share a radially symmetric calcium carbonate skeleton (termed stereom) that is supported by collagenous ligaments.¹ Sea urchins possess spines composed of calcite crystals, which radiate from their body and play a role in locomotion and defense against predators—namely sea otters, starfish/sea stars, wolf eels, and triggerfish, among others (Figure).⁵ These brittle spines can easily penetrate human skin and subsequently break off the sea urchin body. Most species of sea urchins possess solid spines, but a small percentage (80 of approximately 700 extant species) have hollow spines containing various toxic substances.⁶ Penetration and systemic absorption of the toxins within these spines can generate severe systemic responses.

The venomous flower urchin (Toxopneustes pileolus), found in the Indian and Pacific oceans, is one of the more common species known to produce a systemic reaction involving neuromuscular blockage.^7-9 The most common species harvested off the Pacific coast of the United States—Strongylocentrotus purpuratus (purple sea urchin) and Strongylocentrotus franciscanus (red sea urchins)—are not inherently venomous.⁸

Presentation and Diagnosis of Sea Urchin Injuries

Sea urchin injuries have a wide range of manifestations depending on the number of spines involved, the presence of venom, the depth and location of spine penetration, the duration of spine retention in the skin, and the time before treatment initiation. The most common site of sea urchin injury unsurprisingly is the lower extremities and feet, often in the context of divers and swimmers walking across the sea floor. The hands are another frequently injured site, along with the legs, arms, back, scalp, and even oral mucosa.¹¹

Although clinical history and presentation frequently reveal the mechanism of aquatic injury, patients often are unsure of the agent to which they were exposed and may be unaware of retained foreign bodies. Dermoscopy can distinguish the distinct lines radiating from the core of sea urchin spines from other foreign bodies lodged within the skin.⁶ It also can be used to locate spines for removal or for their analysis following punch biopsy.^6,12 The radiopaque nature of sea urchin spines makes radiography and magnetic resonance imaging useful tools in assessment of periarticular soft-tissue damage and spine removal.^8,11,13 Ultrasonography can reveal spines that no longer appear on radiography due to absorption by human tissue.¹⁴

Immediate Dermatologic Effects

Sea urchin injuries can be broadly categorized into immediate and delayed reactions. Immediate manifestations of contact with sea urchin spines include localized pain, bleeding, erythema, myalgia, and edema at the site of injury that can last from a few hours to 1 week without proper wound care and spine removal.⁵ Systemic symptoms ranging from dizziness, lightheadedness, paresthesia, aphonia, paralysis, coma, and death generally are only seen following injuries from venomous species, attachment of pedicellariae, injuries involving neurovascular structures, or penetration by more than 15 spines.^7,11

Initial treatment includes soaking the wound in hot water (113 °F [45 °C]) for 30 to 90 minutes and subsequently removing spines and pedicellariae to prevent development of delayed reactions.^5,15,16 The compounds in the sea urchin epithelium are heat labile and will be inactivated upon soaking in hot water.¹⁶ Extraction of spines can be difficult, as they are brittle and easily break in the skin. Successful removal has been reported using forceps and a hypodermic needle as well as excision; both approaches may require local anesthesia.^8,17 Another technique involves freezing the localized area with liquid nitrogen to allow easier removal upon skin blistering.¹⁸ Punch biopsy also has been utilized as an effective means of ensuring all spiny fragments are removed.^9,19,20 These spines often cause black or purple tattoolike staining at the puncture site, which can persist for a few days after spine extraction.⁸ Ablation using the erbium-doped:YAG laser may be helpful for removal of associated pigment.^21,22

Delayed Dermatologic Effects

Delayed reactions to sea urchin injuries often are attributable to prolonged retention of spines in the skin. Granulomatous reactions typically manifest 2 weeks after injury as firm nonsuppurative nodules with central umbilication and a hyperkeratotic surface.⁷ These nodules may or may not be painful. Histopathology most often reveals foreign body and sarcoidal-type granulomatous reactions. However, tuberculoid, necrobiotic, and suppurative granulomas also may develop.¹³ Other microscopic features include inflammatory reactions, suppurative dermatitis, focal necrosis, and microabscesses.²³ Wounds with progression to granulomatous disease often require surgical debridement.

Other more serious sequalae can result from involvement of joint capsules, especially in the hands and feet. Sea urchin injury involving joint spaces should be treated aggressively, as progression to inflammatory or infectious synovitis and tenosynovitis can cause irreversible loss of joint function. Inflammatory synovitis occurs 1 to 2 months on average after injury following a period of minimal symptoms and begins as a gradual increase in joint swelling and decrease in range of motion.⁸ Infectious tenosynovitis manifests quite similarly. Although suppurative etiologies generally progress with a more acute onset, certain infectious organisms (eg, Mycobacterium) take on an indolent course and should not be overlooked as a cause of delayed symptoms.⁸ The Kavanel cardinal signs are a sensitive tool used in the diagnosis of infectious flexor sheath tenosynovitis.^8,24 If suspicion for joint infection is high, emergency referral should be made for debridement and culture-guided antibiotic therapy. Left untreated, infectious tenosynovitis can result in tendon necrosis or rupture, digit necrosis, and systemic infection.²⁴ Patients with joint involvement should be referred to specialty care (eg, hand surgeon), as they often require synovectomy and surgical removal of foreign material.⁸

From 1 month to 1 year after injury, prolonged granulomatous synovitis of the hand may eventually lead to joint destruction known as “sea urchin arthritis.” These patients present with decreased range of motion and numerous nodules on the hand with a hyperkeratotic surface. Radiography reveals joint space narrowing, osteolysis, subchondral sclerosis, and periosteal reaction. Synovectomy and debridement are necessary to prevent irreversible joint damage or the need for arthrodesis and bone grafting.²⁴

Other Treatment Considerations

Other important considerations in the care of sea urchin spine injuries include assessment of tetanus immunization status and administration of necessary prophylaxis as soon as possible, even in delayed presentations (Table).^16,25 Cultures should be taken only if infection is suspected. Prophylactic antibiotics are not recommended unless the patient is immunocompromised or otherwise has impaired wound healing. If a patient presents with systemic symptoms, they should be referred to an emergency care facility for further management.

Final Thoughts

Sea urchin injuries can lead to serious complications if not diagnosed quickly and treated properly. Retention of sea urchin spines in the deep tissues and joint spaces may lead to granulomas, inflammatory and infectious tenosynovitis (including mycobacterial infection), and sea urchin arthritis requiring surgical debridement and possible irreversible joint damage, up to a year after initial injury. Patients should be educated on the possibility of developing these delayed reactions and instructed to seek immediate care. Joint deformities, range-of-motion deficits, and involvement of neurovascular structures should be considered emergent and referred for proper management. Shoes and diving gear offer some protection but are easily penetrable by sharp sea urchin spines. Preventive focus should be aimed at educating patients and providers on the importance of prompt spine removal upon injury. Although dermatologic and systemic manifestations vary widely, a thorough history, physical examination, and appropriate use of imaging modalities can facilitate accurate diagnosis and guide treatment.

Sea urchins—members of the phylum Echinodermata and the class Echinoidea—are spiny marine invertebrates. Their consumption of fleshy algae makes them essential players in maintaining reef ecosystems.^1,2 Echinoids, a class that includes heart urchins and sand dollars, are ubiquitous in benthic marine environments, both free floating and rock boring, and inhabit a wide range of latitudes spanning from polar oceans to warm seas.³ Despite their immobility and nonaggression, sea urchin puncture wounds are common among divers, snorkelers, swimmers, surfers, and fishers who accidentally come into contact with their sharp spines. Although the epidemiology of sea urchin exposure and injury is difficult to assess, the American Association of Poison Control Centers’ most recent annual report in 2022 documents approximately 1426 annual aquatic bites and/or envenomations.⁴

Sea Urchin Morphology and Toxicity

Echinoderms (a term of Greek origin meaning spiny skin) share a radially symmetric calcium carbonate skeleton (termed stereom) that is supported by collagenous ligaments.¹ Sea urchins possess spines composed of calcite crystals, which radiate from their body and play a role in locomotion and defense against predators—namely sea otters, starfish/sea stars, wolf eels, and triggerfish, among others (Figure).⁵ These brittle spines can easily penetrate human skin and subsequently break off the sea urchin body. Most species of sea urchins possess solid spines, but a small percentage (80 of approximately 700 extant species) have hollow spines containing various toxic substances.⁶ Penetration and systemic absorption of the toxins within these spines can generate severe systemic responses.

The venomous flower urchin (Toxopneustes pileolus), found in the Indian and Pacific oceans, is one of the more common species known to produce a systemic reaction involving neuromuscular blockage.^7-9 The most common species harvested off the Pacific coast of the United States—Strongylocentrotus purpuratus (purple sea urchin) and Strongylocentrotus franciscanus (red sea urchins)—are not inherently venomous.⁸

Presentation and Diagnosis of Sea Urchin Injuries

Sea urchin injuries have a wide range of manifestations depending on the number of spines involved, the presence of venom, the depth and location of spine penetration, the duration of spine retention in the skin, and the time before treatment initiation. The most common site of sea urchin injury unsurprisingly is the lower extremities and feet, often in the context of divers and swimmers walking across the sea floor. The hands are another frequently injured site, along with the legs, arms, back, scalp, and even oral mucosa.¹¹

Although clinical history and presentation frequently reveal the mechanism of aquatic injury, patients often are unsure of the agent to which they were exposed and may be unaware of retained foreign bodies. Dermoscopy can distinguish the distinct lines radiating from the core of sea urchin spines from other foreign bodies lodged within the skin.⁶ It also can be used to locate spines for removal or for their analysis following punch biopsy.^6,12 The radiopaque nature of sea urchin spines makes radiography and magnetic resonance imaging useful tools in assessment of periarticular soft-tissue damage and spine removal.^8,11,13 Ultrasonography can reveal spines that no longer appear on radiography due to absorption by human tissue.¹⁴

Immediate Dermatologic Effects

Sea urchin injuries can be broadly categorized into immediate and delayed reactions. Immediate manifestations of contact with sea urchin spines include localized pain, bleeding, erythema, myalgia, and edema at the site of injury that can last from a few hours to 1 week without proper wound care and spine removal.⁵ Systemic symptoms ranging from dizziness, lightheadedness, paresthesia, aphonia, paralysis, coma, and death generally are only seen following injuries from venomous species, attachment of pedicellariae, injuries involving neurovascular structures, or penetration by more than 15 spines.^7,11

Initial treatment includes soaking the wound in hot water (113 °F [45 °C]) for 30 to 90 minutes and subsequently removing spines and pedicellariae to prevent development of delayed reactions.^5,15,16 The compounds in the sea urchin epithelium are heat labile and will be inactivated upon soaking in hot water.¹⁶ Extraction of spines can be difficult, as they are brittle and easily break in the skin. Successful removal has been reported using forceps and a hypodermic needle as well as excision; both approaches may require local anesthesia.^8,17 Another technique involves freezing the localized area with liquid nitrogen to allow easier removal upon skin blistering.¹⁸ Punch biopsy also has been utilized as an effective means of ensuring all spiny fragments are removed.^9,19,20 These spines often cause black or purple tattoolike staining at the puncture site, which can persist for a few days after spine extraction.⁸ Ablation using the erbium-doped:YAG laser may be helpful for removal of associated pigment.^21,22

Delayed Dermatologic Effects

Delayed reactions to sea urchin injuries often are attributable to prolonged retention of spines in the skin. Granulomatous reactions typically manifest 2 weeks after injury as firm nonsuppurative nodules with central umbilication and a hyperkeratotic surface.⁷ These nodules may or may not be painful. Histopathology most often reveals foreign body and sarcoidal-type granulomatous reactions. However, tuberculoid, necrobiotic, and suppurative granulomas also may develop.¹³ Other microscopic features include inflammatory reactions, suppurative dermatitis, focal necrosis, and microabscesses.²³ Wounds with progression to granulomatous disease often require surgical debridement.

Other more serious sequalae can result from involvement of joint capsules, especially in the hands and feet. Sea urchin injury involving joint spaces should be treated aggressively, as progression to inflammatory or infectious synovitis and tenosynovitis can cause irreversible loss of joint function. Inflammatory synovitis occurs 1 to 2 months on average after injury following a period of minimal symptoms and begins as a gradual increase in joint swelling and decrease in range of motion.⁸ Infectious tenosynovitis manifests quite similarly. Although suppurative etiologies generally progress with a more acute onset, certain infectious organisms (eg, Mycobacterium) take on an indolent course and should not be overlooked as a cause of delayed symptoms.⁸ The Kavanel cardinal signs are a sensitive tool used in the diagnosis of infectious flexor sheath tenosynovitis.^8,24 If suspicion for joint infection is high, emergency referral should be made for debridement and culture-guided antibiotic therapy. Left untreated, infectious tenosynovitis can result in tendon necrosis or rupture, digit necrosis, and systemic infection.²⁴ Patients with joint involvement should be referred to specialty care (eg, hand surgeon), as they often require synovectomy and surgical removal of foreign material.⁸

From 1 month to 1 year after injury, prolonged granulomatous synovitis of the hand may eventually lead to joint destruction known as “sea urchin arthritis.” These patients present with decreased range of motion and numerous nodules on the hand with a hyperkeratotic surface. Radiography reveals joint space narrowing, osteolysis, subchondral sclerosis, and periosteal reaction. Synovectomy and debridement are necessary to prevent irreversible joint damage or the need for arthrodesis and bone grafting.²⁴

Other Treatment Considerations

Other important considerations in the care of sea urchin spine injuries include assessment of tetanus immunization status and administration of necessary prophylaxis as soon as possible, even in delayed presentations (Table).^16,25 Cultures should be taken only if infection is suspected. Prophylactic antibiotics are not recommended unless the patient is immunocompromised or otherwise has impaired wound healing. If a patient presents with systemic symptoms, they should be referred to an emergency care facility for further management.

Final Thoughts

Sea urchin injuries can lead to serious complications if not diagnosed quickly and treated properly. Retention of sea urchin spines in the deep tissues and joint spaces may lead to granulomas, inflammatory and infectious tenosynovitis (including mycobacterial infection), and sea urchin arthritis requiring surgical debridement and possible irreversible joint damage, up to a year after initial injury. Patients should be educated on the possibility of developing these delayed reactions and instructed to seek immediate care. Joint deformities, range-of-motion deficits, and involvement of neurovascular structures should be considered emergent and referred for proper management. Shoes and diving gear offer some protection but are easily penetrable by sharp sea urchin spines. Preventive focus should be aimed at educating patients and providers on the importance of prompt spine removal upon injury. Although dermatologic and systemic manifestations vary widely, a thorough history, physical examination, and appropriate use of imaging modalities can facilitate accurate diagnosis and guide treatment.

The filamentous cyanobacterium Lyngbya majuscula causes irritant contact dermatitis in beachgoers, fishers, and divers in tropical and subtropical marine environments worldwide.¹ If fragments of L majuscula lodge in swimmers’ bathing suits, the toxins can become trapped against the skin and cause seaweed dermatitis.² With climate change resulting in warmer oceans and more extreme storms, L majuscula blooms likely will become more frequent and widespread, thereby increasing the risk for human exposure.^3,4 Herein, we describe the irritants that lead to dermatitis, clinical presentation, and prevention and management of seaweed dermatitis.

Identifying Features and Distribution of Plant

Lyngbya majuscula belongs to the family Oscillatoriaceae; these cyanobacteria grow as filaments and exhibit slow oscillating movements. Commonly referred to as blanketweed or mermaid’s hair due to its appearance, L majuscula grows fine hairlike clumps resembling a mass of olive-colored matted hair.¹ Its thin filaments are 10- to 30-cm long and vary in color from red to white to brown.⁵ Microscopically, a rouleauxlike arrangement of discs provides the structure of each filament.⁶

First identified in Hawaii in 1912, L majuscula was not associated with seaweed dermatitis or dermatotoxicity by the medical community until the first outbreak occurred in Oahu in 1958, though fishermen and beachgoers previously had recognized a relationship between this particular seaweed and skin irritation.^5,7 The first reporting included 125 confirmed cases, with many more mild unreported cases suspected.⁶ Now reported in about 100 locations worldwide, seaweed dermatitis outbreaks have occurred in Australia; Okinawa, Japan; Florida; and the Hawaiian and Marshall islands.^1,2

Exposure to Seaweed

Lyngbya majuscula produces more than 70 biologically active compounds that irritate the skin, eyes, and respiratory system.^2,8 It grows in marine and estuarine environments attached to seagrass, sand, and bedrock at depths of up to 30 m. Warm waters and maximal sunlight provide optimal growth conditions for L majuscula; therefore, the greatest risk for exposure occurs in the Northern and Southern hemispheres in the 1- to 2-month period following their summer solstices.⁵ Runoff during heavy rainfall, which is rich in soil extracts such as phosphorous, iron, and organic carbon, stimulates L majuscula growth and contributes to increased algal blooms.⁴

Dermatitis and Irritants

The dermatoxins Lyngbyatoxin A (LA) and debromoaplysiatoxin (DAT) cause the inflammatory and necrotic appearance of seaweed dermatitis.^1,2,5,8 Lyngbyatoxin A is an indole alkaloid that is closely related to telocidin B, a poisonous compound associated with Streptomyces bacteria.⁹ Sampling of L majuscula and extraction of the dermatoxin, along with human and animal studies, confirmed DAT irritates the skin and induces dermatitis.^5,6Stylocheilus longicauda (sea hare) feeds on L majuscula and contains isolates of DAT in its digestive tract.

Samples of L majuscula taken from several Hawaiian Islands where seaweed dermatitis outbreaks have occurred were examined for differences in toxicities via 6-hour patch tests on human skin.⁶ The samples obtained from the windward side of Oahu contained DAT and aplysiatoxin, while those obtained from the leeward side and Kahala Beach primarily contained LA. Although DAT and LA are vastly different in their molecular structures, testing elicited the same biologic response and induced the same level of skin irritation.⁶ Interestingly, not all strands of L majuscula produced LA and DAT and caused seaweed dermatitis; those that did lead to irritation were more red in color than nontoxic blooms.^5,9

Cutaneous Manifestations

Seaweed dermatitis resembles chemical and thermal burns, ranging from a mild skin rash to severe contact dermatitis with itchy, swollen, ulcerated lesions.^1,7 Patients typically develop a burning or itching sensation beneath their bathing suit or wetsuit that progresses to an erythematous papulovesicular eruption 2 to 24 hours after exposure.^2,6 Within a week, vesicles and bullae desquamate, leaving behind tender erosions.^1,2,6,8 Inframammary lesions are common in females and scrotal swelling in males.^1,6 There is no known association between length of time spent in the water and severity of symptoms.⁵

Most reactions to L majuscula occur from exposure in the water; however, particles that become aerosolized during strong winds or storms can cause seaweed dermatitis on the face. Inhalation of L majuscula may lead to mucous membrane ulceration and pulmonary edema.^1,5,6 Noncutaneous manifestations of seaweed dermatitis include headache, fatigue, and swelling of the eyes, nose, and throat (Figures 1 and 2).^1,5

Prevention and Management

To prevent seaweed dermatitis, avoid swimming in ocean water during L majuscula blooms,¹⁰ which frequently occur following the summer solstices in the Northern and Southern hemispheres.⁵ The National Centers for Coastal Ocean Science Harmful Algae Bloom Monitoring System provides real-time access to algae bloom locations.¹¹ Although this monitoring system is not specific to L majuscula, it may be helpful in determining where potential blooms are. Wearing protective clothing such as coveralls may benefit individuals who enter the water during blooms, but it does not guarantee protection.¹⁰

Currently, there is no treatment for seaweed dermatitis, but symptom management may reduce discomfort and pain. Washing affected skin with soap and water within an hour of exposure may help reduce the severity of seaweed dermatitis, though studies have shown mixed results.^6,7 Application of cool compresses and soothing ointments (eg, calamine) provide symptomatic relief and promote healing.⁷ The dermatitis typically self-resolves within 1 week.

The filamentous cyanobacterium Lyngbya majuscula causes irritant contact dermatitis in beachgoers, fishers, and divers in tropical and subtropical marine environments worldwide.¹ If fragments of L majuscula lodge in swimmers’ bathing suits, the toxins can become trapped against the skin and cause seaweed dermatitis.² With climate change resulting in warmer oceans and more extreme storms, L majuscula blooms likely will become more frequent and widespread, thereby increasing the risk for human exposure.^3,4 Herein, we describe the irritants that lead to dermatitis, clinical presentation, and prevention and management of seaweed dermatitis.

Identifying Features and Distribution of Plant

Lyngbya majuscula belongs to the family Oscillatoriaceae; these cyanobacteria grow as filaments and exhibit slow oscillating movements. Commonly referred to as blanketweed or mermaid’s hair due to its appearance, L majuscula grows fine hairlike clumps resembling a mass of olive-colored matted hair.¹ Its thin filaments are 10- to 30-cm long and vary in color from red to white to brown.⁵ Microscopically, a rouleauxlike arrangement of discs provides the structure of each filament.⁶

First identified in Hawaii in 1912, L majuscula was not associated with seaweed dermatitis or dermatotoxicity by the medical community until the first outbreak occurred in Oahu in 1958, though fishermen and beachgoers previously had recognized a relationship between this particular seaweed and skin irritation.^5,7 The first reporting included 125 confirmed cases, with many more mild unreported cases suspected.⁶ Now reported in about 100 locations worldwide, seaweed dermatitis outbreaks have occurred in Australia; Okinawa, Japan; Florida; and the Hawaiian and Marshall islands.^1,2

Exposure to Seaweed

Lyngbya majuscula produces more than 70 biologically active compounds that irritate the skin, eyes, and respiratory system.^2,8 It grows in marine and estuarine environments attached to seagrass, sand, and bedrock at depths of up to 30 m. Warm waters and maximal sunlight provide optimal growth conditions for L majuscula; therefore, the greatest risk for exposure occurs in the Northern and Southern hemispheres in the 1- to 2-month period following their summer solstices.⁵ Runoff during heavy rainfall, which is rich in soil extracts such as phosphorous, iron, and organic carbon, stimulates L majuscula growth and contributes to increased algal blooms.⁴

Dermatitis and Irritants

The dermatoxins Lyngbyatoxin A (LA) and debromoaplysiatoxin (DAT) cause the inflammatory and necrotic appearance of seaweed dermatitis.^1,2,5,8 Lyngbyatoxin A is an indole alkaloid that is closely related to telocidin B, a poisonous compound associated with Streptomyces bacteria.⁹ Sampling of L majuscula and extraction of the dermatoxin, along with human and animal studies, confirmed DAT irritates the skin and induces dermatitis.^5,6Stylocheilus longicauda (sea hare) feeds on L majuscula and contains isolates of DAT in its digestive tract.

Samples of L majuscula taken from several Hawaiian Islands where seaweed dermatitis outbreaks have occurred were examined for differences in toxicities via 6-hour patch tests on human skin.⁶ The samples obtained from the windward side of Oahu contained DAT and aplysiatoxin, while those obtained from the leeward side and Kahala Beach primarily contained LA. Although DAT and LA are vastly different in their molecular structures, testing elicited the same biologic response and induced the same level of skin irritation.⁶ Interestingly, not all strands of L majuscula produced LA and DAT and caused seaweed dermatitis; those that did lead to irritation were more red in color than nontoxic blooms.^5,9

Cutaneous Manifestations

Seaweed dermatitis resembles chemical and thermal burns, ranging from a mild skin rash to severe contact dermatitis with itchy, swollen, ulcerated lesions.^1,7 Patients typically develop a burning or itching sensation beneath their bathing suit or wetsuit that progresses to an erythematous papulovesicular eruption 2 to 24 hours after exposure.^2,6 Within a week, vesicles and bullae desquamate, leaving behind tender erosions.^1,2,6,8 Inframammary lesions are common in females and scrotal swelling in males.^1,6 There is no known association between length of time spent in the water and severity of symptoms.⁵

Most reactions to L majuscula occur from exposure in the water; however, particles that become aerosolized during strong winds or storms can cause seaweed dermatitis on the face. Inhalation of L majuscula may lead to mucous membrane ulceration and pulmonary edema.^1,5,6 Noncutaneous manifestations of seaweed dermatitis include headache, fatigue, and swelling of the eyes, nose, and throat (Figures 1 and 2).^1,5

Prevention and Management

To prevent seaweed dermatitis, avoid swimming in ocean water during L majuscula blooms,¹⁰ which frequently occur following the summer solstices in the Northern and Southern hemispheres.⁵ The National Centers for Coastal Ocean Science Harmful Algae Bloom Monitoring System provides real-time access to algae bloom locations.¹¹ Although this monitoring system is not specific to L majuscula, it may be helpful in determining where potential blooms are. Wearing protective clothing such as coveralls may benefit individuals who enter the water during blooms, but it does not guarantee protection.¹⁰

Currently, there is no treatment for seaweed dermatitis, but symptom management may reduce discomfort and pain. Washing affected skin with soap and water within an hour of exposure may help reduce the severity of seaweed dermatitis, though studies have shown mixed results.^6,7 Application of cool compresses and soothing ointments (eg, calamine) provide symptomatic relief and promote healing.⁷ The dermatitis typically self-resolves within 1 week.

The filamentous cyanobacterium Lyngbya majuscula causes irritant contact dermatitis in beachgoers, fishers, and divers in tropical and subtropical marine environments worldwide.¹ If fragments of L majuscula lodge in swimmers’ bathing suits, the toxins can become trapped against the skin and cause seaweed dermatitis.² With climate change resulting in warmer oceans and more extreme storms, L majuscula blooms likely will become more frequent and widespread, thereby increasing the risk for human exposure.^3,4 Herein, we describe the irritants that lead to dermatitis, clinical presentation, and prevention and management of seaweed dermatitis.

Identifying Features and Distribution of Plant

Lyngbya majuscula belongs to the family Oscillatoriaceae; these cyanobacteria grow as filaments and exhibit slow oscillating movements. Commonly referred to as blanketweed or mermaid’s hair due to its appearance, L majuscula grows fine hairlike clumps resembling a mass of olive-colored matted hair.¹ Its thin filaments are 10- to 30-cm long and vary in color from red to white to brown.⁵ Microscopically, a rouleauxlike arrangement of discs provides the structure of each filament.⁶

First identified in Hawaii in 1912, L majuscula was not associated with seaweed dermatitis or dermatotoxicity by the medical community until the first outbreak occurred in Oahu in 1958, though fishermen and beachgoers previously had recognized a relationship between this particular seaweed and skin irritation.^5,7 The first reporting included 125 confirmed cases, with many more mild unreported cases suspected.⁶ Now reported in about 100 locations worldwide, seaweed dermatitis outbreaks have occurred in Australia; Okinawa, Japan; Florida; and the Hawaiian and Marshall islands.^1,2

Exposure to Seaweed

Lyngbya majuscula produces more than 70 biologically active compounds that irritate the skin, eyes, and respiratory system.^2,8 It grows in marine and estuarine environments attached to seagrass, sand, and bedrock at depths of up to 30 m. Warm waters and maximal sunlight provide optimal growth conditions for L majuscula; therefore, the greatest risk for exposure occurs in the Northern and Southern hemispheres in the 1- to 2-month period following their summer solstices.⁵ Runoff during heavy rainfall, which is rich in soil extracts such as phosphorous, iron, and organic carbon, stimulates L majuscula growth and contributes to increased algal blooms.⁴

Dermatitis and Irritants

The dermatoxins Lyngbyatoxin A (LA) and debromoaplysiatoxin (DAT) cause the inflammatory and necrotic appearance of seaweed dermatitis.^1,2,5,8 Lyngbyatoxin A is an indole alkaloid that is closely related to telocidin B, a poisonous compound associated with Streptomyces bacteria.⁹ Sampling of L majuscula and extraction of the dermatoxin, along with human and animal studies, confirmed DAT irritates the skin and induces dermatitis.^5,6Stylocheilus longicauda (sea hare) feeds on L majuscula and contains isolates of DAT in its digestive tract.

Samples of L majuscula taken from several Hawaiian Islands where seaweed dermatitis outbreaks have occurred were examined for differences in toxicities via 6-hour patch tests on human skin.⁶ The samples obtained from the windward side of Oahu contained DAT and aplysiatoxin, while those obtained from the leeward side and Kahala Beach primarily contained LA. Although DAT and LA are vastly different in their molecular structures, testing elicited the same biologic response and induced the same level of skin irritation.⁶ Interestingly, not all strands of L majuscula produced LA and DAT and caused seaweed dermatitis; those that did lead to irritation were more red in color than nontoxic blooms.^5,9

Cutaneous Manifestations

Seaweed dermatitis resembles chemical and thermal burns, ranging from a mild skin rash to severe contact dermatitis with itchy, swollen, ulcerated lesions.^1,7 Patients typically develop a burning or itching sensation beneath their bathing suit or wetsuit that progresses to an erythematous papulovesicular eruption 2 to 24 hours after exposure.^2,6 Within a week, vesicles and bullae desquamate, leaving behind tender erosions.^1,2,6,8 Inframammary lesions are common in females and scrotal swelling in males.^1,6 There is no known association between length of time spent in the water and severity of symptoms.⁵

Most reactions to L majuscula occur from exposure in the water; however, particles that become aerosolized during strong winds or storms can cause seaweed dermatitis on the face. Inhalation of L majuscula may lead to mucous membrane ulceration and pulmonary edema.^1,5,6 Noncutaneous manifestations of seaweed dermatitis include headache, fatigue, and swelling of the eyes, nose, and throat (Figures 1 and 2).^1,5

Prevention and Management

To prevent seaweed dermatitis, avoid swimming in ocean water during L majuscula blooms,¹⁰ which frequently occur following the summer solstices in the Northern and Southern hemispheres.⁵ The National Centers for Coastal Ocean Science Harmful Algae Bloom Monitoring System provides real-time access to algae bloom locations.¹¹ Although this monitoring system is not specific to L majuscula, it may be helpful in determining where potential blooms are. Wearing protective clothing such as coveralls may benefit individuals who enter the water during blooms, but it does not guarantee protection.¹⁰

Currently, there is no treatment for seaweed dermatitis, but symptom management may reduce discomfort and pain. Washing affected skin with soap and water within an hour of exposure may help reduce the severity of seaweed dermatitis, though studies have shown mixed results.^6,7 Application of cool compresses and soothing ointments (eg, calamine) provide symptomatic relief and promote healing.⁷ The dermatitis typically self-resolves within 1 week.

Plant Parts and Nomenclature

Ficus carica (common fig) is a deciduous shrub or small tree with smooth gray bark that can grow up to 10 m in height (Figure 1). It is characterized by many spreading branches, but the trunk rarely grows beyond a diameter of 7 in. Its hairy leaves are coarse on the upper side and soft underneath with 3 to 7 deep lobes that can extend up to 25 cm in length or width; the leaves grow individually, alternating along the sides of the branches. Fig trees often can be seen adorning yards, gardens, and parks, especially in tropical and subtropical climates. Ficus carica should not be confused with Ficus benjamina (weeping fig), a common ornamental tree that also is used to provide shade in hot climates, though both can cause phototoxic skin eruptions.

The common fig tree originated in the Mediterranean and western Asia¹ and has been cultivated by humans since the second and third millennia bc for its fruit, which commonly is used to sweeten cookies, cakes, and jams.² Figs are the most commonly mentioned food plant in the Bible, with at least 56 references in the Old and New Testaments.³ The “fruit” technically is a syconium—a hollow fleshy receptacle with a small opening at the apex partly closed by small scales. It can be obovoid, turbinate, or pear shaped; can be 1 to 4 inches long; and can vary in color from yellowish green to coppery, bronze, or dark purple (Figure 2).

Ficus carica is a member of the Moraceae family (derived from the Latin name for the mulberry tree), which includes 53 genera and approximately 1400 species, of which about 850 belong to the genus Ficus (the Latin name for a fig tree). The term carica likely comes from the Latin word carricare (to load) to describe a tree loaded with figs. Family members include trees, shrubs, lianas, and herbs that usually contain laticifers with a milky latex.

Traditional Uses

For centuries, components of the fig tree have been used in herbal teas and pastes to treat ailments ranging from sore throats to diarrhea, though there is no evidence to support their efficacy.⁴ Ancient Indians and Egyptians used plants such as the common fig tree containing furocoumarins to induce hyperpigmentation in vitiligo.⁵

Phototoxic Components

The leaves and sap of the common fig tree contain psoralens, which are members of the furocoumarin group of chemical compounds and are the source of its phototoxicity. The fruit does not contain psoralens.^6-9 The tree also produces proteolytic enzymes such as protease, amylase, ficin, triterpenoids, and lipodiastase that enhance its phototoxic effects.⁸ Exposure to UV light between 320 and 400 nm following contact with these phototoxic components triggers a reaction in the skin over the course of 1 to 3 days.⁵ The psoralens bind in epidermal cells, cross-link the DNA, and cause cell-membrane destruction, leading to edema and necrosis.¹⁰ The delay in symptoms may be attributed to the time needed to synthesize acute-phase reaction proteins such as tumor necrosis factor α and IL-1.¹¹ In spring and summer months, an increased concentration of psoralens in the leaves and sap contribute to an increased incidence of phytophotodermatitis.⁹ Humidity and sweat also increase the percutaneous absorption of psoralens.^12,13

Allergens

Fig trees produce a latex protein that can cause cross-reactive hypersensitivity reactions in those allergic to F benjamina latex and rubber latex.⁶ The latex proteins in fig trees can act as airborne respiratory allergens. Ingestion of figs can produce anaphylactic reactions in those sensitized to rubber latex and F benjamina latex.⁷ Other plant families associated with phototoxic reactions include Rutaceae (lemon, lime, bitter orange), Apiaceae (formerly Umbelliferae)(carrot, parsnip, parsley, dill, celery, hogweed), and Fabaceae (prairie turnip).

Most cases of fig phytophotodermatitis begin with burning, pain, and/or itching within hours of sunlight exposure in areas of the skin that encountered components of the fig tree, often in a linear pattern. The affected areas become erythematous and edematous with formation of bullae and unilocular vesicles over the course of 1 to 3 days.^12,14,15 Lesions may extend beyond the region of contact with the fig tree as they spread across the skin due to sweat or friction, and pain may linger even after the lesions resolve.^12,13,16 Adults who handle fig trees (eg, pruning) are susceptible to phototoxic reactions, especially those using chain saws or other mechanisms that result in spray exposure, as the photosensitizing sap permeates the wood and bark of the entire tree.¹⁷ Similarly, children who handle fig leaves or sap during outdoor play can develop bullous eruptions. Severe cases have resulted in hospital admission after prolonged exposure.¹⁶ Additionally, irritant dermatitis may arise from contact with the trichomes or “hairs” on various parts of the plant.

Image provided with permission by Scott Norton, MD, MPH, MSc (Washington, DC).

Patients who use natural remedies containing components of the fig tree without the supervision of a medical provider put themselves at risk for unsafe or unwanted adverse effects, such as phytophotodermatitis.^12,15,16,18 An entire family presented with burns after they applied fig leaf extract to the skin prior to tanning outside in the sun.¹⁹ A 42-year-old woman acquired a severe burn covering 81% of the body surface after topically applying fig leaf tea to the skin as a tanning agent.²⁰ A subset of patients ingesting or applying fig tree components for conditions such as vitiligo, dermatitis, onychomycosis, and motor retardation developed similar cutaneous reactions.^13,14,21,22 Lesions resembling finger marks can raise concerns for potential abuse or neglect in children.²²

The differential diagnosis for fig phytophotodermatitis includes sunburn, chemical burns, drug-related photosensitivity, infectious lesions (eg, herpes simplex, bullous impetigo, Lyme disease, superficial lymphangitis), connective tissue disease (eg, systemic lupus erythematosus), contact dermatitis, and nonaccidental trauma.^12,15,18 Compared to sunburn, phytophotodermatitis tends to increase in severity over days following exposure and heals with dramatic hyperpigmentation, which also prompts visits to dermatology.¹²

Treatment

Treatment of fig phytophotodermatitis chiefly is symptomatic, including analgesia, appropriate wound care, and infection prophylaxis. Topical and systemic corticosteroids may aid in the resolution of moderate to severe reactions.^15,23,24 Even severe injuries over small areas or mild injuries to a high percentage of the total body surface area may require treatment in a burn unit. Patients should be encouraged to use mineral-based sunscreens on the affected areas to reduce the risk for hyperpigmentation. Individuals who regularly handle fig trees should use contact barriers including gloves and protective clothing (eg, long-sleeved shirts, long pants).

Plant Parts and Nomenclature

Ficus carica (common fig) is a deciduous shrub or small tree with smooth gray bark that can grow up to 10 m in height (Figure 1). It is characterized by many spreading branches, but the trunk rarely grows beyond a diameter of 7 in. Its hairy leaves are coarse on the upper side and soft underneath with 3 to 7 deep lobes that can extend up to 25 cm in length or width; the leaves grow individually, alternating along the sides of the branches. Fig trees often can be seen adorning yards, gardens, and parks, especially in tropical and subtropical climates. Ficus carica should not be confused with Ficus benjamina (weeping fig), a common ornamental tree that also is used to provide shade in hot climates, though both can cause phototoxic skin eruptions.

The common fig tree originated in the Mediterranean and western Asia¹ and has been cultivated by humans since the second and third millennia bc for its fruit, which commonly is used to sweeten cookies, cakes, and jams.² Figs are the most commonly mentioned food plant in the Bible, with at least 56 references in the Old and New Testaments.³ The “fruit” technically is a syconium—a hollow fleshy receptacle with a small opening at the apex partly closed by small scales. It can be obovoid, turbinate, or pear shaped; can be 1 to 4 inches long; and can vary in color from yellowish green to coppery, bronze, or dark purple (Figure 2).

Ficus carica is a member of the Moraceae family (derived from the Latin name for the mulberry tree), which includes 53 genera and approximately 1400 species, of which about 850 belong to the genus Ficus (the Latin name for a fig tree). The term carica likely comes from the Latin word carricare (to load) to describe a tree loaded with figs. Family members include trees, shrubs, lianas, and herbs that usually contain laticifers with a milky latex.

Traditional Uses

For centuries, components of the fig tree have been used in herbal teas and pastes to treat ailments ranging from sore throats to diarrhea, though there is no evidence to support their efficacy.⁴ Ancient Indians and Egyptians used plants such as the common fig tree containing furocoumarins to induce hyperpigmentation in vitiligo.⁵

Phototoxic Components

The leaves and sap of the common fig tree contain psoralens, which are members of the furocoumarin group of chemical compounds and are the source of its phototoxicity. The fruit does not contain psoralens.^6-9 The tree also produces proteolytic enzymes such as protease, amylase, ficin, triterpenoids, and lipodiastase that enhance its phototoxic effects.⁸ Exposure to UV light between 320 and 400 nm following contact with these phototoxic components triggers a reaction in the skin over the course of 1 to 3 days.⁵ The psoralens bind in epidermal cells, cross-link the DNA, and cause cell-membrane destruction, leading to edema and necrosis.¹⁰ The delay in symptoms may be attributed to the time needed to synthesize acute-phase reaction proteins such as tumor necrosis factor α and IL-1.¹¹ In spring and summer months, an increased concentration of psoralens in the leaves and sap contribute to an increased incidence of phytophotodermatitis.⁹ Humidity and sweat also increase the percutaneous absorption of psoralens.^12,13

Allergens

Fig trees produce a latex protein that can cause cross-reactive hypersensitivity reactions in those allergic to F benjamina latex and rubber latex.⁶ The latex proteins in fig trees can act as airborne respiratory allergens. Ingestion of figs can produce anaphylactic reactions in those sensitized to rubber latex and F benjamina latex.⁷ Other plant families associated with phototoxic reactions include Rutaceae (lemon, lime, bitter orange), Apiaceae (formerly Umbelliferae)(carrot, parsnip, parsley, dill, celery, hogweed), and Fabaceae (prairie turnip).

Most cases of fig phytophotodermatitis begin with burning, pain, and/or itching within hours of sunlight exposure in areas of the skin that encountered components of the fig tree, often in a linear pattern. The affected areas become erythematous and edematous with formation of bullae and unilocular vesicles over the course of 1 to 3 days.^12,14,15 Lesions may extend beyond the region of contact with the fig tree as they spread across the skin due to sweat or friction, and pain may linger even after the lesions resolve.^12,13,16 Adults who handle fig trees (eg, pruning) are susceptible to phototoxic reactions, especially those using chain saws or other mechanisms that result in spray exposure, as the photosensitizing sap permeates the wood and bark of the entire tree.¹⁷ Similarly, children who handle fig leaves or sap during outdoor play can develop bullous eruptions. Severe cases have resulted in hospital admission after prolonged exposure.¹⁶ Additionally, irritant dermatitis may arise from contact with the trichomes or “hairs” on various parts of the plant.

Image provided with permission by Scott Norton, MD, MPH, MSc (Washington, DC).

Patients who use natural remedies containing components of the fig tree without the supervision of a medical provider put themselves at risk for unsafe or unwanted adverse effects, such as phytophotodermatitis.^12,15,16,18 An entire family presented with burns after they applied fig leaf extract to the skin prior to tanning outside in the sun.¹⁹ A 42-year-old woman acquired a severe burn covering 81% of the body surface after topically applying fig leaf tea to the skin as a tanning agent.²⁰ A subset of patients ingesting or applying fig tree components for conditions such as vitiligo, dermatitis, onychomycosis, and motor retardation developed similar cutaneous reactions.^13,14,21,22 Lesions resembling finger marks can raise concerns for potential abuse or neglect in children.²²

The differential diagnosis for fig phytophotodermatitis includes sunburn, chemical burns, drug-related photosensitivity, infectious lesions (eg, herpes simplex, bullous impetigo, Lyme disease, superficial lymphangitis), connective tissue disease (eg, systemic lupus erythematosus), contact dermatitis, and nonaccidental trauma.^12,15,18 Compared to sunburn, phytophotodermatitis tends to increase in severity over days following exposure and heals with dramatic hyperpigmentation, which also prompts visits to dermatology.¹²

Treatment

Treatment of fig phytophotodermatitis chiefly is symptomatic, including analgesia, appropriate wound care, and infection prophylaxis. Topical and systemic corticosteroids may aid in the resolution of moderate to severe reactions.^15,23,24 Even severe injuries over small areas or mild injuries to a high percentage of the total body surface area may require treatment in a burn unit. Patients should be encouraged to use mineral-based sunscreens on the affected areas to reduce the risk for hyperpigmentation. Individuals who regularly handle fig trees should use contact barriers including gloves and protective clothing (eg, long-sleeved shirts, long pants).

Plant Parts and Nomenclature

Ficus carica (common fig) is a deciduous shrub or small tree with smooth gray bark that can grow up to 10 m in height (Figure 1). It is characterized by many spreading branches, but the trunk rarely grows beyond a diameter of 7 in. Its hairy leaves are coarse on the upper side and soft underneath with 3 to 7 deep lobes that can extend up to 25 cm in length or width; the leaves grow individually, alternating along the sides of the branches. Fig trees often can be seen adorning yards, gardens, and parks, especially in tropical and subtropical climates. Ficus carica should not be confused with Ficus benjamina (weeping fig), a common ornamental tree that also is used to provide shade in hot climates, though both can cause phototoxic skin eruptions.

The common fig tree originated in the Mediterranean and western Asia¹ and has been cultivated by humans since the second and third millennia bc for its fruit, which commonly is used to sweeten cookies, cakes, and jams.² Figs are the most commonly mentioned food plant in the Bible, with at least 56 references in the Old and New Testaments.³ The “fruit” technically is a syconium—a hollow fleshy receptacle with a small opening at the apex partly closed by small scales. It can be obovoid, turbinate, or pear shaped; can be 1 to 4 inches long; and can vary in color from yellowish green to coppery, bronze, or dark purple (Figure 2).

Ficus carica is a member of the Moraceae family (derived from the Latin name for the mulberry tree), which includes 53 genera and approximately 1400 species, of which about 850 belong to the genus Ficus (the Latin name for a fig tree). The term carica likely comes from the Latin word carricare (to load) to describe a tree loaded with figs. Family members include trees, shrubs, lianas, and herbs that usually contain laticifers with a milky latex.

Traditional Uses

For centuries, components of the fig tree have been used in herbal teas and pastes to treat ailments ranging from sore throats to diarrhea, though there is no evidence to support their efficacy.⁴ Ancient Indians and Egyptians used plants such as the common fig tree containing furocoumarins to induce hyperpigmentation in vitiligo.⁵

Phototoxic Components

The leaves and sap of the common fig tree contain psoralens, which are members of the furocoumarin group of chemical compounds and are the source of its phototoxicity. The fruit does not contain psoralens.^6-9 The tree also produces proteolytic enzymes such as protease, amylase, ficin, triterpenoids, and lipodiastase that enhance its phototoxic effects.⁸ Exposure to UV light between 320 and 400 nm following contact with these phototoxic components triggers a reaction in the skin over the course of 1 to 3 days.⁵ The psoralens bind in epidermal cells, cross-link the DNA, and cause cell-membrane destruction, leading to edema and necrosis.¹⁰ The delay in symptoms may be attributed to the time needed to synthesize acute-phase reaction proteins such as tumor necrosis factor α and IL-1.¹¹ In spring and summer months, an increased concentration of psoralens in the leaves and sap contribute to an increased incidence of phytophotodermatitis.⁹ Humidity and sweat also increase the percutaneous absorption of psoralens.^12,13

Allergens

Fig trees produce a latex protein that can cause cross-reactive hypersensitivity reactions in those allergic to F benjamina latex and rubber latex.⁶ The latex proteins in fig trees can act as airborne respiratory allergens. Ingestion of figs can produce anaphylactic reactions in those sensitized to rubber latex and F benjamina latex.⁷ Other plant families associated with phototoxic reactions include Rutaceae (lemon, lime, bitter orange), Apiaceae (formerly Umbelliferae)(carrot, parsnip, parsley, dill, celery, hogweed), and Fabaceae (prairie turnip).

Most cases of fig phytophotodermatitis begin with burning, pain, and/or itching within hours of sunlight exposure in areas of the skin that encountered components of the fig tree, often in a linear pattern. The affected areas become erythematous and edematous with formation of bullae and unilocular vesicles over the course of 1 to 3 days.^12,14,15 Lesions may extend beyond the region of contact with the fig tree as they spread across the skin due to sweat or friction, and pain may linger even after the lesions resolve.^12,13,16 Adults who handle fig trees (eg, pruning) are susceptible to phototoxic reactions, especially those using chain saws or other mechanisms that result in spray exposure, as the photosensitizing sap permeates the wood and bark of the entire tree.¹⁷ Similarly, children who handle fig leaves or sap during outdoor play can develop bullous eruptions. Severe cases have resulted in hospital admission after prolonged exposure.¹⁶ Additionally, irritant dermatitis may arise from contact with the trichomes or “hairs” on various parts of the plant.

Image provided with permission by Scott Norton, MD, MPH, MSc (Washington, DC).

Patients who use natural remedies containing components of the fig tree without the supervision of a medical provider put themselves at risk for unsafe or unwanted adverse effects, such as phytophotodermatitis.^12,15,16,18 An entire family presented with burns after they applied fig leaf extract to the skin prior to tanning outside in the sun.¹⁹ A 42-year-old woman acquired a severe burn covering 81% of the body surface after topically applying fig leaf tea to the skin as a tanning agent.²⁰ A subset of patients ingesting or applying fig tree components for conditions such as vitiligo, dermatitis, onychomycosis, and motor retardation developed similar cutaneous reactions.^13,14,21,22 Lesions resembling finger marks can raise concerns for potential abuse or neglect in children.²²

The differential diagnosis for fig phytophotodermatitis includes sunburn, chemical burns, drug-related photosensitivity, infectious lesions (eg, herpes simplex, bullous impetigo, Lyme disease, superficial lymphangitis), connective tissue disease (eg, systemic lupus erythematosus), contact dermatitis, and nonaccidental trauma.^12,15,18 Compared to sunburn, phytophotodermatitis tends to increase in severity over days following exposure and heals with dramatic hyperpigmentation, which also prompts visits to dermatology.¹²

Treatment

Treatment of fig phytophotodermatitis chiefly is symptomatic, including analgesia, appropriate wound care, and infection prophylaxis. Topical and systemic corticosteroids may aid in the resolution of moderate to severe reactions.^15,23,24 Even severe injuries over small areas or mild injuries to a high percentage of the total body surface area may require treatment in a burn unit. Patients should be encouraged to use mineral-based sunscreens on the affected areas to reduce the risk for hyperpigmentation. Individuals who regularly handle fig trees should use contact barriers including gloves and protective clothing (eg, long-sleeved shirts, long pants).

Carpet beetle larvae of the family Dermestidae have been documented to cause both acute and delayed hypersensitivity reactions in susceptible individuals. These larvae have specialized horizontal rows of spear-shaped hairs called hastisetae, which detach easily into the surrounding environment and are small enough to travel by air. Exposure to hastisetae has been tied to adverse effects ranging from dermatitis to rhinoconjunctivitis and acute asthma, with treatment being mostly empiric and symptom based. Due to the pervasiveness of carpet beetles in homes, improved awareness of dermestid-induced manifestations is valuable for clinicians.

Beetles in the Dermestidae family do not bite humans but have been reported to cause skin reactions in addition to other symptoms typical of an allergic reaction. Skin contact with larval hairs (hastisetae) of these insects—known as carpet, larder, or hide beetles — may cause urticarial or edematous papules that are mistaken for papular urticaria or arthropod bites. ¹ There are approximately 500 to 700 species of carpet beetles worldwide. Carpet beetles are a clinically underrecognized cause of allergic contact dermatitis given their frequent presence in homes across the world. ² Carpet beetle larvae feed on shed skin, feathers, hair, wool, book bindings, felt, leather, wood, silk, and sometimes grains and thus can be found nearly anywhere. Most symptom-inducing exposures to Dermestidae beetles occur occupationally, such as in museum curators working hands-on with collection materials and workers handling infested materials such as wool. ^3,4 In-home Dermestidae exposure may lead to symptoms, especially if regularly worn clothing and bedding materials are infested. The broad palate of dermestid members has resulted in substantial contamination of stored materials such as flour and fabric in addition to the destruction of museum collections. ^5-7

The larvae of some dermestid species, most commonly of the genera Anthrenus and Dermestes, are 2 to 3 mm in length and have detachable hairlike hastisetae that shed into the surrounding environment throughout larval development (Figure 1).⁸ The hastisetae, located on the thoracic and abdominal segments (tergites), serve as a larval defense mechanism. When prodded, the round, hairy, wormlike larvae tense up and can raise their abdominal tergites while splaying the hastisetae out in a fanlike manner.⁹ Similar to porcupine quills, the hastisetae easily detach and can entrap the appendages of invertebrate predators. Hastisetae are not known to be sharp enough to puncture human skin, but friction and irritation from skin contact and superficial sticking of the hastisetae into mucous membranes and noncornified epithelium, such as in the bronchial airways, are thought to induce hypersensitivity reactions in susceptible individuals.

Additionally, hastisetae and the exoskeletons of both adult and larval dermestid beetles are composed mostly of chitin, which is highly allergenic. Chitin has been found to play a proinflammatory role in ocular inflammation, asthma, and bronchial reactivity via T helper cell (T_H2)–mediated cellular interactions.^10-12 Larvae shed their exoskeletons, including hastisetae, multiple times over the course of their development, which contributes to their potential allergen burden (Figure 2). Reports of positive prick and/or patch testing to larval components indicate some cases of both acute type 1 and delayed type 4 hypersensitivity reactions.^4,8,13

Clinical Presentation and Diagnosis

Multiple erythematous urticarial papules, papulopustules, and papulovesicles are the typical manifestations of dermestid dermatitis.^3,4,13-16 Figure 3 demonstrates several characteristic edematous papules with background erythema. Unlike the clusters seen with flea and bed bug bites, dermestid-induced lesions typically are single and scattered, with a propensity for exposed limbs and the face. Exposure to hastisetae commonly results in classic allergic symptoms including rhinitis, conjunctivitis, coughing, wheezing, sneezing, and intranasal and periocular pruritus, even in those with no personal history of atopy.^17-19 Lymphadenopathy, vasculitis, and allergic alveolitis also have been reported.²⁰ A large infestation in which many individual beetles as well as larvae can be found in 1 or more areas of the inhabited structure has been reported to cause more severe symptoms, including acute eczema, otitis externa, lymphocytic vasculitis, and allergic alveolitis, all of which resolved within 3 months of thorough deinfestation cleaning.²¹

Skin-prick and/or patch testing is not necessary for this clinical diagnosis of dermestid-induced allergic contact dermatitis. This diagnosis is bolstered by (but does not require a history of) repeated symptom induction upon performing certain activities (eg, handling taxidermy specimens) and/or in certain environments (eg, only at home). Because of individual differences in hypersensitivity to dermestid parts, it is not typical for all members of a household to be affected.

When there are multiple potential suspected allergens or an unknown cause for symptoms despite a detailed history, allergy testing can be useful in confirming a diagnosis and directing management. Immediate-onset type 1 hypersensitivity reactions are evaluated using skin-prick testing or serum IgE levels, whereas delayed type 4 hypersensitivity reactions can be evaluated using patch testing. Type 1 reactions tend to present with classic allergy symptoms, especially where there are abundant mast cells to degranulate in the skin and mucosa of the gastrointestinal and respiratory tracts; these symptoms range from mild wheezing, urticaria, periorbital pruritus, and sneezing to outright asthma, diarrhea, rhinoconjunctivitis, and even anaphylaxis. With these reactions, initial exposure to an antigen such as chitin in the hastisetae leads to an asymptomatic sensitization against the antigen in which its introduction leads to a T_H2-skewed cellular response, which promotes B-cell production of IgE antibodies. Upon subsequent exposure to this antigen, IgE antibodies bound to mast cells will lead them to degranulate with release of histamine and other proinflammatory molecules, resulting in clinical manifestations. The skin-prick test relies on introduction of potential antigens through the epidermis into the dermis with a sharp lancet to induce IgE antibody activation and then degranulation of the patient’s mast cells, resulting in a pruritic erythematous wheal. This IgE-mediated process has been shown to occur in response to dermestid larval parts among household dust, resulting in chronic coughing, sneezing, nasal pruritus, and asthma.^15,17,22

Type 4 hypersensitivity reactions are T-cell mediated and also include a sensitization phase followed by symptom manifestation upon repeat exposure; however, these reactions usually are not immediate and can take up to 72 hours after exposure to manifest.²³ This is because T cells specific to the antigen do not lead a process resulting in antibodies but instead recruit numerous other T_H1-polarized mediators upon re-exposure to activate cytotoxic CD8⁺ T cells and macrophages to attempt to neutralize the antigen. Many type 4 reactions result in mostly cutaneous manifestations, such as contact dermatitis. Patch testing involves adhering potential allergens to the skin for a time with assessments at regular intervals to evaluate the level of reaction from weakly positive to severe. At minimum, most reports of dermestid-related manifestations include a rash such as erythematous papules, and several published cases involving patch testing have yielded positive results to various preparations of larval parts.^3,14,21

Management and Treatment

Prevention of dermestid exposure is difficult given the myriad materials eaten by the larvae. An insect exterminator should verify and treat a carpet beetle infestation, while a dermatologist can treat symptomatic individuals. Treatment is driven by the severity of the patient’s discomfort and is aimed at both symptomatic relief and reducing dermestid exposure moving forward. Although in certain environments it will be nearly impossible to eradicate Dermestidae, cleaning thoroughly and regularly may go far to reduce exposure and associated symptoms.

Clothing and other materials such as bedding that will have direct skin contact should be washed to remove hastisetae and be stored in airtight containers in addition to items made with animal fibers, such as wool sweaters and down blankets. Mattresses, flooring, rugs, curtains, and other amenable areas should be vacuumed thoroughly, and the vacuum bag should be placed in the trash afterward. Protective pillow and mattress covers should be used. Stuffed animals in infested areas should be thrown away if not able to be completely washed and dried. Air conditioning systems may spread larval hairs away from the site of infestation and should be cleaned as much as possible. Surfaces where beetles and larvae also are commonly seen, such as windowsills, and hidden among closet and pantry items should also be wiped clean to remove both insects and potential substrate. In one case, scraping the wood flooring and applying a thick coat of varnish in addition to removing all stuffed animals from an affected individual’s home allowed for resolution of symptoms.¹⁷

Treatment for symptoms includes topical anti-inflammatory agents and/or oral antihistamines, with improvement in symptoms typically occurring within days and resolution dependent on level of exposure moving forward.

Final Thoughts

There is a broad overlap between dermestid habitats and human-occupied environments; thus, the opportunities for exposure and sensitization to allergenic dermestid parts are numerous. Dermatologists should be aware of the possible manifestations from dermestid exposure.

Carpet beetle larvae of the family Dermestidae have been documented to cause both acute and delayed hypersensitivity reactions in susceptible individuals. These larvae have specialized horizontal rows of spear-shaped hairs called hastisetae, which detach easily into the surrounding environment and are small enough to travel by air. Exposure to hastisetae has been tied to adverse effects ranging from dermatitis to rhinoconjunctivitis and acute asthma, with treatment being mostly empiric and symptom based. Due to the pervasiveness of carpet beetles in homes, improved awareness of dermestid-induced manifestations is valuable for clinicians.

Beetles in the Dermestidae family do not bite humans but have been reported to cause skin reactions in addition to other symptoms typical of an allergic reaction. Skin contact with larval hairs (hastisetae) of these insects—known as carpet, larder, or hide beetles — may cause urticarial or edematous papules that are mistaken for papular urticaria or arthropod bites. ¹ There are approximately 500 to 700 species of carpet beetles worldwide. Carpet beetles are a clinically underrecognized cause of allergic contact dermatitis given their frequent presence in homes across the world. ² Carpet beetle larvae feed on shed skin, feathers, hair, wool, book bindings, felt, leather, wood, silk, and sometimes grains and thus can be found nearly anywhere. Most symptom-inducing exposures to Dermestidae beetles occur occupationally, such as in museum curators working hands-on with collection materials and workers handling infested materials such as wool. ^3,4 In-home Dermestidae exposure may lead to symptoms, especially if regularly worn clothing and bedding materials are infested. The broad palate of dermestid members has resulted in substantial contamination of stored materials such as flour and fabric in addition to the destruction of museum collections. ^5-7

The larvae of some dermestid species, most commonly of the genera Anthrenus and Dermestes, are 2 to 3 mm in length and have detachable hairlike hastisetae that shed into the surrounding environment throughout larval development (Figure 1).⁸ The hastisetae, located on the thoracic and abdominal segments (tergites), serve as a larval defense mechanism. When prodded, the round, hairy, wormlike larvae tense up and can raise their abdominal tergites while splaying the hastisetae out in a fanlike manner.⁹ Similar to porcupine quills, the hastisetae easily detach and can entrap the appendages of invertebrate predators. Hastisetae are not known to be sharp enough to puncture human skin, but friction and irritation from skin contact and superficial sticking of the hastisetae into mucous membranes and noncornified epithelium, such as in the bronchial airways, are thought to induce hypersensitivity reactions in susceptible individuals.

Additionally, hastisetae and the exoskeletons of both adult and larval dermestid beetles are composed mostly of chitin, which is highly allergenic. Chitin has been found to play a proinflammatory role in ocular inflammation, asthma, and bronchial reactivity via T helper cell (T_H2)–mediated cellular interactions.^10-12 Larvae shed their exoskeletons, including hastisetae, multiple times over the course of their development, which contributes to their potential allergen burden (Figure 2). Reports of positive prick and/or patch testing to larval components indicate some cases of both acute type 1 and delayed type 4 hypersensitivity reactions.^4,8,13

Clinical Presentation and Diagnosis

Multiple erythematous urticarial papules, papulopustules, and papulovesicles are the typical manifestations of dermestid dermatitis.^3,4,13-16 Figure 3 demonstrates several characteristic edematous papules with background erythema. Unlike the clusters seen with flea and bed bug bites, dermestid-induced lesions typically are single and scattered, with a propensity for exposed limbs and the face. Exposure to hastisetae commonly results in classic allergic symptoms including rhinitis, conjunctivitis, coughing, wheezing, sneezing, and intranasal and periocular pruritus, even in those with no personal history of atopy.^17-19 Lymphadenopathy, vasculitis, and allergic alveolitis also have been reported.²⁰ A large infestation in which many individual beetles as well as larvae can be found in 1 or more areas of the inhabited structure has been reported to cause more severe symptoms, including acute eczema, otitis externa, lymphocytic vasculitis, and allergic alveolitis, all of which resolved within 3 months of thorough deinfestation cleaning.²¹

Skin-prick and/or patch testing is not necessary for this clinical diagnosis of dermestid-induced allergic contact dermatitis. This diagnosis is bolstered by (but does not require a history of) repeated symptom induction upon performing certain activities (eg, handling taxidermy specimens) and/or in certain environments (eg, only at home). Because of individual differences in hypersensitivity to dermestid parts, it is not typical for all members of a household to be affected.

When there are multiple potential suspected allergens or an unknown cause for symptoms despite a detailed history, allergy testing can be useful in confirming a diagnosis and directing management. Immediate-onset type 1 hypersensitivity reactions are evaluated using skin-prick testing or serum IgE levels, whereas delayed type 4 hypersensitivity reactions can be evaluated using patch testing. Type 1 reactions tend to present with classic allergy symptoms, especially where there are abundant mast cells to degranulate in the skin and mucosa of the gastrointestinal and respiratory tracts; these symptoms range from mild wheezing, urticaria, periorbital pruritus, and sneezing to outright asthma, diarrhea, rhinoconjunctivitis, and even anaphylaxis. With these reactions, initial exposure to an antigen such as chitin in the hastisetae leads to an asymptomatic sensitization against the antigen in which its introduction leads to a T_H2-skewed cellular response, which promotes B-cell production of IgE antibodies. Upon subsequent exposure to this antigen, IgE antibodies bound to mast cells will lead them to degranulate with release of histamine and other proinflammatory molecules, resulting in clinical manifestations. The skin-prick test relies on introduction of potential antigens through the epidermis into the dermis with a sharp lancet to induce IgE antibody activation and then degranulation of the patient’s mast cells, resulting in a pruritic erythematous wheal. This IgE-mediated process has been shown to occur in response to dermestid larval parts among household dust, resulting in chronic coughing, sneezing, nasal pruritus, and asthma.^15,17,22

Type 4 hypersensitivity reactions are T-cell mediated and also include a sensitization phase followed by symptom manifestation upon repeat exposure; however, these reactions usually are not immediate and can take up to 72 hours after exposure to manifest.²³ This is because T cells specific to the antigen do not lead a process resulting in antibodies but instead recruit numerous other T_H1-polarized mediators upon re-exposure to activate cytotoxic CD8⁺ T cells and macrophages to attempt to neutralize the antigen. Many type 4 reactions result in mostly cutaneous manifestations, such as contact dermatitis. Patch testing involves adhering potential allergens to the skin for a time with assessments at regular intervals to evaluate the level of reaction from weakly positive to severe. At minimum, most reports of dermestid-related manifestations include a rash such as erythematous papules, and several published cases involving patch testing have yielded positive results to various preparations of larval parts.^3,14,21

Management and Treatment

Prevention of dermestid exposure is difficult given the myriad materials eaten by the larvae. An insect exterminator should verify and treat a carpet beetle infestation, while a dermatologist can treat symptomatic individuals. Treatment is driven by the severity of the patient’s discomfort and is aimed at both symptomatic relief and reducing dermestid exposure moving forward. Although in certain environments it will be nearly impossible to eradicate Dermestidae, cleaning thoroughly and regularly may go far to reduce exposure and associated symptoms.

Clothing and other materials such as bedding that will have direct skin contact should be washed to remove hastisetae and be stored in airtight containers in addition to items made with animal fibers, such as wool sweaters and down blankets. Mattresses, flooring, rugs, curtains, and other amenable areas should be vacuumed thoroughly, and the vacuum bag should be placed in the trash afterward. Protective pillow and mattress covers should be used. Stuffed animals in infested areas should be thrown away if not able to be completely washed and dried. Air conditioning systems may spread larval hairs away from the site of infestation and should be cleaned as much as possible. Surfaces where beetles and larvae also are commonly seen, such as windowsills, and hidden among closet and pantry items should also be wiped clean to remove both insects and potential substrate. In one case, scraping the wood flooring and applying a thick coat of varnish in addition to removing all stuffed animals from an affected individual’s home allowed for resolution of symptoms.¹⁷

Treatment for symptoms includes topical anti-inflammatory agents and/or oral antihistamines, with improvement in symptoms typically occurring within days and resolution dependent on level of exposure moving forward.

Final Thoughts

There is a broad overlap between dermestid habitats and human-occupied environments; thus, the opportunities for exposure and sensitization to allergenic dermestid parts are numerous. Dermatologists should be aware of the possible manifestations from dermestid exposure.

Carpet beetle larvae of the family Dermestidae have been documented to cause both acute and delayed hypersensitivity reactions in susceptible individuals. These larvae have specialized horizontal rows of spear-shaped hairs called hastisetae, which detach easily into the surrounding environment and are small enough to travel by air. Exposure to hastisetae has been tied to adverse effects ranging from dermatitis to rhinoconjunctivitis and acute asthma, with treatment being mostly empiric and symptom based. Due to the pervasiveness of carpet beetles in homes, improved awareness of dermestid-induced manifestations is valuable for clinicians.

Beetles in the Dermestidae family do not bite humans but have been reported to cause skin reactions in addition to other symptoms typical of an allergic reaction. Skin contact with larval hairs (hastisetae) of these insects—known as carpet, larder, or hide beetles — may cause urticarial or edematous papules that are mistaken for papular urticaria or arthropod bites. ¹ There are approximately 500 to 700 species of carpet beetles worldwide. Carpet beetles are a clinically underrecognized cause of allergic contact dermatitis given their frequent presence in homes across the world. ² Carpet beetle larvae feed on shed skin, feathers, hair, wool, book bindings, felt, leather, wood, silk, and sometimes grains and thus can be found nearly anywhere. Most symptom-inducing exposures to Dermestidae beetles occur occupationally, such as in museum curators working hands-on with collection materials and workers handling infested materials such as wool. ^3,4 In-home Dermestidae exposure may lead to symptoms, especially if regularly worn clothing and bedding materials are infested. The broad palate of dermestid members has resulted in substantial contamination of stored materials such as flour and fabric in addition to the destruction of museum collections. ^5-7

The larvae of some dermestid species, most commonly of the genera Anthrenus and Dermestes, are 2 to 3 mm in length and have detachable hairlike hastisetae that shed into the surrounding environment throughout larval development (Figure 1).⁸ The hastisetae, located on the thoracic and abdominal segments (tergites), serve as a larval defense mechanism. When prodded, the round, hairy, wormlike larvae tense up and can raise their abdominal tergites while splaying the hastisetae out in a fanlike manner.⁹ Similar to porcupine quills, the hastisetae easily detach and can entrap the appendages of invertebrate predators. Hastisetae are not known to be sharp enough to puncture human skin, but friction and irritation from skin contact and superficial sticking of the hastisetae into mucous membranes and noncornified epithelium, such as in the bronchial airways, are thought to induce hypersensitivity reactions in susceptible individuals.

Additionally, hastisetae and the exoskeletons of both adult and larval dermestid beetles are composed mostly of chitin, which is highly allergenic. Chitin has been found to play a proinflammatory role in ocular inflammation, asthma, and bronchial reactivity via T helper cell (T_H2)–mediated cellular interactions.^10-12 Larvae shed their exoskeletons, including hastisetae, multiple times over the course of their development, which contributes to their potential allergen burden (Figure 2). Reports of positive prick and/or patch testing to larval components indicate some cases of both acute type 1 and delayed type 4 hypersensitivity reactions.^4,8,13

Clinical Presentation and Diagnosis

Multiple erythematous urticarial papules, papulopustules, and papulovesicles are the typical manifestations of dermestid dermatitis.^3,4,13-16 Figure 3 demonstrates several characteristic edematous papules with background erythema. Unlike the clusters seen with flea and bed bug bites, dermestid-induced lesions typically are single and scattered, with a propensity for exposed limbs and the face. Exposure to hastisetae commonly results in classic allergic symptoms including rhinitis, conjunctivitis, coughing, wheezing, sneezing, and intranasal and periocular pruritus, even in those with no personal history of atopy.^17-19 Lymphadenopathy, vasculitis, and allergic alveolitis also have been reported.²⁰ A large infestation in which many individual beetles as well as larvae can be found in 1 or more areas of the inhabited structure has been reported to cause more severe symptoms, including acute eczema, otitis externa, lymphocytic vasculitis, and allergic alveolitis, all of which resolved within 3 months of thorough deinfestation cleaning.²¹

Skin-prick and/or patch testing is not necessary for this clinical diagnosis of dermestid-induced allergic contact dermatitis. This diagnosis is bolstered by (but does not require a history of) repeated symptom induction upon performing certain activities (eg, handling taxidermy specimens) and/or in certain environments (eg, only at home). Because of individual differences in hypersensitivity to dermestid parts, it is not typical for all members of a household to be affected.

When there are multiple potential suspected allergens or an unknown cause for symptoms despite a detailed history, allergy testing can be useful in confirming a diagnosis and directing management. Immediate-onset type 1 hypersensitivity reactions are evaluated using skin-prick testing or serum IgE levels, whereas delayed type 4 hypersensitivity reactions can be evaluated using patch testing. Type 1 reactions tend to present with classic allergy symptoms, especially where there are abundant mast cells to degranulate in the skin and mucosa of the gastrointestinal and respiratory tracts; these symptoms range from mild wheezing, urticaria, periorbital pruritus, and sneezing to outright asthma, diarrhea, rhinoconjunctivitis, and even anaphylaxis. With these reactions, initial exposure to an antigen such as chitin in the hastisetae leads to an asymptomatic sensitization against the antigen in which its introduction leads to a T_H2-skewed cellular response, which promotes B-cell production of IgE antibodies. Upon subsequent exposure to this antigen, IgE antibodies bound to mast cells will lead them to degranulate with release of histamine and other proinflammatory molecules, resulting in clinical manifestations. The skin-prick test relies on introduction of potential antigens through the epidermis into the dermis with a sharp lancet to induce IgE antibody activation and then degranulation of the patient’s mast cells, resulting in a pruritic erythematous wheal. This IgE-mediated process has been shown to occur in response to dermestid larval parts among household dust, resulting in chronic coughing, sneezing, nasal pruritus, and asthma.^15,17,22

Type 4 hypersensitivity reactions are T-cell mediated and also include a sensitization phase followed by symptom manifestation upon repeat exposure; however, these reactions usually are not immediate and can take up to 72 hours after exposure to manifest.²³ This is because T cells specific to the antigen do not lead a process resulting in antibodies but instead recruit numerous other T_H1-polarized mediators upon re-exposure to activate cytotoxic CD8⁺ T cells and macrophages to attempt to neutralize the antigen. Many type 4 reactions result in mostly cutaneous manifestations, such as contact dermatitis. Patch testing involves adhering potential allergens to the skin for a time with assessments at regular intervals to evaluate the level of reaction from weakly positive to severe. At minimum, most reports of dermestid-related manifestations include a rash such as erythematous papules, and several published cases involving patch testing have yielded positive results to various preparations of larval parts.^3,14,21

Management and Treatment

Prevention of dermestid exposure is difficult given the myriad materials eaten by the larvae. An insect exterminator should verify and treat a carpet beetle infestation, while a dermatologist can treat symptomatic individuals. Treatment is driven by the severity of the patient’s discomfort and is aimed at both symptomatic relief and reducing dermestid exposure moving forward. Although in certain environments it will be nearly impossible to eradicate Dermestidae, cleaning thoroughly and regularly may go far to reduce exposure and associated symptoms.

Clothing and other materials such as bedding that will have direct skin contact should be washed to remove hastisetae and be stored in airtight containers in addition to items made with animal fibers, such as wool sweaters and down blankets. Mattresses, flooring, rugs, curtains, and other amenable areas should be vacuumed thoroughly, and the vacuum bag should be placed in the trash afterward. Protective pillow and mattress covers should be used. Stuffed animals in infested areas should be thrown away if not able to be completely washed and dried. Air conditioning systems may spread larval hairs away from the site of infestation and should be cleaned as much as possible. Surfaces where beetles and larvae also are commonly seen, such as windowsills, and hidden among closet and pantry items should also be wiped clean to remove both insects and potential substrate. In one case, scraping the wood flooring and applying a thick coat of varnish in addition to removing all stuffed animals from an affected individual’s home allowed for resolution of symptoms.¹⁷

Treatment for symptoms includes topical anti-inflammatory agents and/or oral antihistamines, with improvement in symptoms typically occurring within days and resolution dependent on level of exposure moving forward.

Final Thoughts

There is a broad overlap between dermestid habitats and human-occupied environments; thus, the opportunities for exposure and sensitization to allergenic dermestid parts are numerous. Dermatologists should be aware of the possible manifestations from dermestid exposure.