Cutis

To the Editor:

The itch-scratch cycle refers to the sequence created when a pruritic skin condition leads to scratching and skin barrier disruption, ultimately facilitating secondary skin changes and neural activation that prolongs pruritus. In patients with pruritic conditions, the itch-scratch cycle often can run unrestrained, with patients unaware of their scratching habits. Understanding what drives a patient to scratch, such as the pleasure gained from scratching, may be beneficial for dermatologists combating a patient’s scratching habits. The earliest documented attempts to understand the mechanism of an itch were made in Greece around the fifth century, but the pathophysiology of this sensation still is not fully understood. The Latin term pruritus refers to itching, irritation, or sexual excitement, while the Greek term knêsmos and related words also denote itch in an irritating or pleasurable sense.¹ This paradoxical duality of irritation and pleasure is a phenomenon all too well understood by those affected with pruritic symptoms.

Although there are many measured characteristics of an itch, the pleasure granted from scratching an itch rarely is addressed. Understanding the factors influencing the pleasurability of scratching could help improve management and outcomes of patients’ pruritic conditions.

Pruritus is associated with a wide array of etiologies including dermatologic, infectious, metabolic, and autoimmune, but unanimously it evokes a strong desire to scratch. Scratching an itch often yields temporary relief from the irritation by dispensing a complex sensory concoction between pleasure and pain.² The neurobiology behind this pleasure phenomenon is inconclusive. Some hypotheses point to how scratching-induced pleasure may be derived from the deactivation or inhibition of the unpleasant sensation of an itch in the central nervous system, the stimulation of the reward signals in the C-fiber system in the peripheral nervous system, the release of pruritis-inhibiting prostaglandin D2, or a combination of these pathways. Levels of sensation and pleasure induced from itch attenuation by scratching even vary based on anatomic location. One study demonstrated that, when compared to the forearms, the ankles and back perceived baseline induced itch most intensely, but no significant difference in perceived itch intensity was found between the ankles and back. Additionally, scratching an itchy back or ankle notably induced more pleasure when compared to the forearms, but there was no significant difference in scratching pleasurability between the ankle and back.³

Although there are adequate questionnaires and scales (eg, ItchyQoL,⁴ Skindex-16, Skindex-29) to quantify the severity of pruritus and its effects on a patient’s quality of life, these measurements do not assess the pleasure yielded from scratching, the impact of scratch pleasure on the patient experience, or the effect of scratch pleasure on the disease state.⁴ It appears that there are inadequate assessment tools to define factors associated with the pleasurability of scratching. A PubMed search of articles indexed for MEDLINE using the terms scratching pleasure scale and pruritus pleasure questionnaire yielded scarce results measuring patient perspectives on scratching-associated pleasure. A pertinent study performed by O’Neill et al⁵ compared the differences in itch characteristics between patients with psoriasis and those with atopic dermatitis using a web-based questionnaire featuring a numerical pleasure scale (ranging from −5 [highly unpleasurable] to +5 [highly pleasurable]) on an 11-point Likert scale. The questionnaire sought to measure the effects of scratching during a typical episode of itch within the past 2 weeks. Scratching was found pleasurable in both groups of patients.⁵ Another web-based questionnaire that characterized pleasurability in scratching a typical episode of itch in individuals with atopic dermatitis using a −5 to +5 Likert scale (−5 [highly unpleasurable] to +5 [highly pleasurable]) found that most participants perceived scratching as pleasurable and that there was a positive correlation between itch intensity and scratch pleasurability.⁶ Both of these studies quantified that scratching an itch is pleasurable, a correlation that may not come as a surprise. This direct correlation suggests that a more detailed analysis of this scratch pleasure could be beneficial in the management of pruritic conditions.

Treating the underlying cause of an itch is key to inhibiting the sensation; in some cases, anti-itch medications must be used. Current medications have limited effects on itch relief, but an expanding understanding of itch pathophysiology through clinical and laboratory research in the fields of dermatology, immunology, and neurology is paving the way for promising new therapeutic medications.^7-11 In a review of the literature, Sanders and Akiyama¹² elucidated the influence of stress and anxiety in scratching an itch and the way in which both pharmacologic and nonpharmacologic (ie, psychological and educational interventions) may be used to help break the itch-scratch cycle. Possible techniques include habit-reversal training, relaxation therapy, and cognitive behavioral therapy.¹³ Understanding patient perspectives on the pleasure yielded from scratching an itch and the disease factors that influence this pleasure seeking are paramount to reducing patient scratching. In understanding the pleasurability of scratching in pruritic conditions, the itch-scratch cycle and its accompanying deleterious effects (eg, stress, anxiety, pain, infection, secondary skin changes) can be broken.

The pleasure yielded from scratching an itch is a component of patient scratching habits that should be analyzed and quantified to reduce itch in pruritic conditions, mitigate damaging consequences of scratching, and improve the quality of life of patients with pruritic conditions. Furthermore, this understanding may help guide clinicians in management, such as counseling patients on the itch-scratch cycle and deciding which forthcoming medications could ameliorate a patient’s pruritic symptoms.

To the Editor:

The itch-scratch cycle refers to the sequence created when a pruritic skin condition leads to scratching and skin barrier disruption, ultimately facilitating secondary skin changes and neural activation that prolongs pruritus. In patients with pruritic conditions, the itch-scratch cycle often can run unrestrained, with patients unaware of their scratching habits. Understanding what drives a patient to scratch, such as the pleasure gained from scratching, may be beneficial for dermatologists combating a patient’s scratching habits. The earliest documented attempts to understand the mechanism of an itch were made in Greece around the fifth century, but the pathophysiology of this sensation still is not fully understood. The Latin term pruritus refers to itching, irritation, or sexual excitement, while the Greek term knêsmos and related words also denote itch in an irritating or pleasurable sense.¹ This paradoxical duality of irritation and pleasure is a phenomenon all too well understood by those affected with pruritic symptoms.

Although there are many measured characteristics of an itch, the pleasure granted from scratching an itch rarely is addressed. Understanding the factors influencing the pleasurability of scratching could help improve management and outcomes of patients’ pruritic conditions.

Pruritus is associated with a wide array of etiologies including dermatologic, infectious, metabolic, and autoimmune, but unanimously it evokes a strong desire to scratch. Scratching an itch often yields temporary relief from the irritation by dispensing a complex sensory concoction between pleasure and pain.² The neurobiology behind this pleasure phenomenon is inconclusive. Some hypotheses point to how scratching-induced pleasure may be derived from the deactivation or inhibition of the unpleasant sensation of an itch in the central nervous system, the stimulation of the reward signals in the C-fiber system in the peripheral nervous system, the release of pruritis-inhibiting prostaglandin D2, or a combination of these pathways. Levels of sensation and pleasure induced from itch attenuation by scratching even vary based on anatomic location. One study demonstrated that, when compared to the forearms, the ankles and back perceived baseline induced itch most intensely, but no significant difference in perceived itch intensity was found between the ankles and back. Additionally, scratching an itchy back or ankle notably induced more pleasure when compared to the forearms, but there was no significant difference in scratching pleasurability between the ankle and back.³

Although there are adequate questionnaires and scales (eg, ItchyQoL,⁴ Skindex-16, Skindex-29) to quantify the severity of pruritus and its effects on a patient’s quality of life, these measurements do not assess the pleasure yielded from scratching, the impact of scratch pleasure on the patient experience, or the effect of scratch pleasure on the disease state.⁴ It appears that there are inadequate assessment tools to define factors associated with the pleasurability of scratching. A PubMed search of articles indexed for MEDLINE using the terms scratching pleasure scale and pruritus pleasure questionnaire yielded scarce results measuring patient perspectives on scratching-associated pleasure. A pertinent study performed by O’Neill et al⁵ compared the differences in itch characteristics between patients with psoriasis and those with atopic dermatitis using a web-based questionnaire featuring a numerical pleasure scale (ranging from −5 [highly unpleasurable] to +5 [highly pleasurable]) on an 11-point Likert scale. The questionnaire sought to measure the effects of scratching during a typical episode of itch within the past 2 weeks. Scratching was found pleasurable in both groups of patients.⁵ Another web-based questionnaire that characterized pleasurability in scratching a typical episode of itch in individuals with atopic dermatitis using a −5 to +5 Likert scale (−5 [highly unpleasurable] to +5 [highly pleasurable]) found that most participants perceived scratching as pleasurable and that there was a positive correlation between itch intensity and scratch pleasurability.⁶ Both of these studies quantified that scratching an itch is pleasurable, a correlation that may not come as a surprise. This direct correlation suggests that a more detailed analysis of this scratch pleasure could be beneficial in the management of pruritic conditions.

Treating the underlying cause of an itch is key to inhibiting the sensation; in some cases, anti-itch medications must be used. Current medications have limited effects on itch relief, but an expanding understanding of itch pathophysiology through clinical and laboratory research in the fields of dermatology, immunology, and neurology is paving the way for promising new therapeutic medications.^7-11 In a review of the literature, Sanders and Akiyama¹² elucidated the influence of stress and anxiety in scratching an itch and the way in which both pharmacologic and nonpharmacologic (ie, psychological and educational interventions) may be used to help break the itch-scratch cycle. Possible techniques include habit-reversal training, relaxation therapy, and cognitive behavioral therapy.¹³ Understanding patient perspectives on the pleasure yielded from scratching an itch and the disease factors that influence this pleasure seeking are paramount to reducing patient scratching. In understanding the pleasurability of scratching in pruritic conditions, the itch-scratch cycle and its accompanying deleterious effects (eg, stress, anxiety, pain, infection, secondary skin changes) can be broken.

The pleasure yielded from scratching an itch is a component of patient scratching habits that should be analyzed and quantified to reduce itch in pruritic conditions, mitigate damaging consequences of scratching, and improve the quality of life of patients with pruritic conditions. Furthermore, this understanding may help guide clinicians in management, such as counseling patients on the itch-scratch cycle and deciding which forthcoming medications could ameliorate a patient’s pruritic symptoms.

To the Editor:

The itch-scratch cycle refers to the sequence created when a pruritic skin condition leads to scratching and skin barrier disruption, ultimately facilitating secondary skin changes and neural activation that prolongs pruritus. In patients with pruritic conditions, the itch-scratch cycle often can run unrestrained, with patients unaware of their scratching habits. Understanding what drives a patient to scratch, such as the pleasure gained from scratching, may be beneficial for dermatologists combating a patient’s scratching habits. The earliest documented attempts to understand the mechanism of an itch were made in Greece around the fifth century, but the pathophysiology of this sensation still is not fully understood. The Latin term pruritus refers to itching, irritation, or sexual excitement, while the Greek term knêsmos and related words also denote itch in an irritating or pleasurable sense.¹ This paradoxical duality of irritation and pleasure is a phenomenon all too well understood by those affected with pruritic symptoms.

Although there are many measured characteristics of an itch, the pleasure granted from scratching an itch rarely is addressed. Understanding the factors influencing the pleasurability of scratching could help improve management and outcomes of patients’ pruritic conditions.

Pruritus is associated with a wide array of etiologies including dermatologic, infectious, metabolic, and autoimmune, but unanimously it evokes a strong desire to scratch. Scratching an itch often yields temporary relief from the irritation by dispensing a complex sensory concoction between pleasure and pain.² The neurobiology behind this pleasure phenomenon is inconclusive. Some hypotheses point to how scratching-induced pleasure may be derived from the deactivation or inhibition of the unpleasant sensation of an itch in the central nervous system, the stimulation of the reward signals in the C-fiber system in the peripheral nervous system, the release of pruritis-inhibiting prostaglandin D2, or a combination of these pathways. Levels of sensation and pleasure induced from itch attenuation by scratching even vary based on anatomic location. One study demonstrated that, when compared to the forearms, the ankles and back perceived baseline induced itch most intensely, but no significant difference in perceived itch intensity was found between the ankles and back. Additionally, scratching an itchy back or ankle notably induced more pleasure when compared to the forearms, but there was no significant difference in scratching pleasurability between the ankle and back.³

Although there are adequate questionnaires and scales (eg, ItchyQoL,⁴ Skindex-16, Skindex-29) to quantify the severity of pruritus and its effects on a patient’s quality of life, these measurements do not assess the pleasure yielded from scratching, the impact of scratch pleasure on the patient experience, or the effect of scratch pleasure on the disease state.⁴ It appears that there are inadequate assessment tools to define factors associated with the pleasurability of scratching. A PubMed search of articles indexed for MEDLINE using the terms scratching pleasure scale and pruritus pleasure questionnaire yielded scarce results measuring patient perspectives on scratching-associated pleasure. A pertinent study performed by O’Neill et al⁵ compared the differences in itch characteristics between patients with psoriasis and those with atopic dermatitis using a web-based questionnaire featuring a numerical pleasure scale (ranging from −5 [highly unpleasurable] to +5 [highly pleasurable]) on an 11-point Likert scale. The questionnaire sought to measure the effects of scratching during a typical episode of itch within the past 2 weeks. Scratching was found pleasurable in both groups of patients.⁵ Another web-based questionnaire that characterized pleasurability in scratching a typical episode of itch in individuals with atopic dermatitis using a −5 to +5 Likert scale (−5 [highly unpleasurable] to +5 [highly pleasurable]) found that most participants perceived scratching as pleasurable and that there was a positive correlation between itch intensity and scratch pleasurability.⁶ Both of these studies quantified that scratching an itch is pleasurable, a correlation that may not come as a surprise. This direct correlation suggests that a more detailed analysis of this scratch pleasure could be beneficial in the management of pruritic conditions.

Treating the underlying cause of an itch is key to inhibiting the sensation; in some cases, anti-itch medications must be used. Current medications have limited effects on itch relief, but an expanding understanding of itch pathophysiology through clinical and laboratory research in the fields of dermatology, immunology, and neurology is paving the way for promising new therapeutic medications.^7-11 In a review of the literature, Sanders and Akiyama¹² elucidated the influence of stress and anxiety in scratching an itch and the way in which both pharmacologic and nonpharmacologic (ie, psychological and educational interventions) may be used to help break the itch-scratch cycle. Possible techniques include habit-reversal training, relaxation therapy, and cognitive behavioral therapy.¹³ Understanding patient perspectives on the pleasure yielded from scratching an itch and the disease factors that influence this pleasure seeking are paramount to reducing patient scratching. In understanding the pleasurability of scratching in pruritic conditions, the itch-scratch cycle and its accompanying deleterious effects (eg, stress, anxiety, pain, infection, secondary skin changes) can be broken.

The pleasure yielded from scratching an itch is a component of patient scratching habits that should be analyzed and quantified to reduce itch in pruritic conditions, mitigate damaging consequences of scratching, and improve the quality of life of patients with pruritic conditions. Furthermore, this understanding may help guide clinicians in management, such as counseling patients on the itch-scratch cycle and deciding which forthcoming medications could ameliorate a patient’s pruritic symptoms.

To the Editor:

Dermatofibromas (also known as fibrous histiocytomas) are benign fibrous nodules that most often arise as solitary lesions on the lower extremities. Multiple eruptive dermatofibromas (MEDFs) are uncommon and have been defined as more than 15 in number¹ or 5 to 8 dermatofibromas appearing within 4 months.² They have been reported in association with a number of conditions of immune dysregulation such as systemic lupus erythematosus, Sjögren syndrome, HIV infection, and leukemia.³ Multiple eruptive dermatofibromas also have been described in patients with Down syndrome (DS).^4-7 We report a case of MEDFs in a patient with DS and review the literature on the association between MEDFs and DS.

A 38-year-old woman with DS, hidradenitis suppurativa, and hypothyroidism presented with multiple cutaneous lesions developing over the last year. The lesions continued to increase in number but were otherwise asymptomatic. Physical examination revealed approximately 20 rubbery, pink-tan papules measuring less than 1 cm in diameter that were scattered along the trunk (Figure, A), arms, and legs (Figure, B).

The patient had no known history of immunosuppression or rheumatologic disease and was otherwise healthy. Basic laboratory tests including a complete blood cell count and antinuclear antibody titer were within reference range. The lesions were clinically consistent with dermatofibromas, but due to their increasing number within a short period of time, a biopsy of a representative lesion was performed to confirm the diagnosis.

The exact incidence of MEDFs is unknown, but they are rare, with one review finding only 50 cases reported from 1960 to 2002.⁸ They are increasingly recognized as a sign of potential immune dysregulation. Approximately 56% to 70% of cases are seen in patients with an underlying disease state; 80% are immune mediated.^8,9 Interestingly, DS has long been associated with notable immune dysfunction,^10,11 with evidence suggesting that trisomy 21 may result in widespread changes in gene expression that can lead to interferon activation.¹²

A PubMed search of articles indexed for MEDLINE using the terms dermatofibroma and Down, dermatofibroma and Down syndrome, eruptive dermatofibroma and Down syndrome, and multiple dermatofibroma and Down syndrome revealed 6 cases of MEDFs in patients with DS that have been reported since 2005.^4-7 An additional report by Honda et al¹³ described a patient with DS who developed 7 dermatofibromas, but no time frame of development was specified. We reviewed the characteristics of 8 patients with DS with MEDFs, which included our patient (Table). The average age at time of presentation was 39 years (median age, 40 years). Six patients (75%) were female and 2 (25%) were male. Dermatofibromas were reported to appear over the course of months to years. Comorbidities included psoriatic arthritis (treated with methotrexate),⁶ thyroid disorders (ie, Graves disease),⁶ hypercholesterolemia,⁶ hidradenitis suppurativa, long-standing mild lymphopenia (1.4×10⁹/L [reference range, 1.5−4.0×10⁹/L]),⁴ and acute megakaryoblastic leukemia¹³ treated 15 years before the appearance of dermatofibromas.

Many dermatologic conditions have been reported at increased rates in individuals with DS, including seborrheic dermatitis, alopecia areata, syringomas, elastosis perforans serpiginosa, cutis marmorata, xerosis, and palmoplantar hyperkeratosis.^14,15 Although drawing conclusions about associations between MEDFs and DS is limited by our small sample size, we have reported this case and reviewed existing cases of MEDFs in DS to highlight a potential association that may be underrecognized or underreported. More evidence is needed to determine the strength of the association between MEDFs and DS, but dermatologists should be aware that MEDFs may be an additional skin finding associated with DS that is related to the syndrome’s immune dysregulation.

To the Editor:

Dermatofibromas (also known as fibrous histiocytomas) are benign fibrous nodules that most often arise as solitary lesions on the lower extremities. Multiple eruptive dermatofibromas (MEDFs) are uncommon and have been defined as more than 15 in number¹ or 5 to 8 dermatofibromas appearing within 4 months.² They have been reported in association with a number of conditions of immune dysregulation such as systemic lupus erythematosus, Sjögren syndrome, HIV infection, and leukemia.³ Multiple eruptive dermatofibromas also have been described in patients with Down syndrome (DS).^4-7 We report a case of MEDFs in a patient with DS and review the literature on the association between MEDFs and DS.

A 38-year-old woman with DS, hidradenitis suppurativa, and hypothyroidism presented with multiple cutaneous lesions developing over the last year. The lesions continued to increase in number but were otherwise asymptomatic. Physical examination revealed approximately 20 rubbery, pink-tan papules measuring less than 1 cm in diameter that were scattered along the trunk (Figure, A), arms, and legs (Figure, B).

The patient had no known history of immunosuppression or rheumatologic disease and was otherwise healthy. Basic laboratory tests including a complete blood cell count and antinuclear antibody titer were within reference range. The lesions were clinically consistent with dermatofibromas, but due to their increasing number within a short period of time, a biopsy of a representative lesion was performed to confirm the diagnosis.

The exact incidence of MEDFs is unknown, but they are rare, with one review finding only 50 cases reported from 1960 to 2002.⁸ They are increasingly recognized as a sign of potential immune dysregulation. Approximately 56% to 70% of cases are seen in patients with an underlying disease state; 80% are immune mediated.^8,9 Interestingly, DS has long been associated with notable immune dysfunction,^10,11 with evidence suggesting that trisomy 21 may result in widespread changes in gene expression that can lead to interferon activation.¹²

A PubMed search of articles indexed for MEDLINE using the terms dermatofibroma and Down, dermatofibroma and Down syndrome, eruptive dermatofibroma and Down syndrome, and multiple dermatofibroma and Down syndrome revealed 6 cases of MEDFs in patients with DS that have been reported since 2005.^4-7 An additional report by Honda et al¹³ described a patient with DS who developed 7 dermatofibromas, but no time frame of development was specified. We reviewed the characteristics of 8 patients with DS with MEDFs, which included our patient (Table). The average age at time of presentation was 39 years (median age, 40 years). Six patients (75%) were female and 2 (25%) were male. Dermatofibromas were reported to appear over the course of months to years. Comorbidities included psoriatic arthritis (treated with methotrexate),⁶ thyroid disorders (ie, Graves disease),⁶ hypercholesterolemia,⁶ hidradenitis suppurativa, long-standing mild lymphopenia (1.4×10⁹/L [reference range, 1.5−4.0×10⁹/L]),⁴ and acute megakaryoblastic leukemia¹³ treated 15 years before the appearance of dermatofibromas.

Many dermatologic conditions have been reported at increased rates in individuals with DS, including seborrheic dermatitis, alopecia areata, syringomas, elastosis perforans serpiginosa, cutis marmorata, xerosis, and palmoplantar hyperkeratosis.^14,15 Although drawing conclusions about associations between MEDFs and DS is limited by our small sample size, we have reported this case and reviewed existing cases of MEDFs in DS to highlight a potential association that may be underrecognized or underreported. More evidence is needed to determine the strength of the association between MEDFs and DS, but dermatologists should be aware that MEDFs may be an additional skin finding associated with DS that is related to the syndrome’s immune dysregulation.

To the Editor:

Dermatofibromas (also known as fibrous histiocytomas) are benign fibrous nodules that most often arise as solitary lesions on the lower extremities. Multiple eruptive dermatofibromas (MEDFs) are uncommon and have been defined as more than 15 in number¹ or 5 to 8 dermatofibromas appearing within 4 months.² They have been reported in association with a number of conditions of immune dysregulation such as systemic lupus erythematosus, Sjögren syndrome, HIV infection, and leukemia.³ Multiple eruptive dermatofibromas also have been described in patients with Down syndrome (DS).^4-7 We report a case of MEDFs in a patient with DS and review the literature on the association between MEDFs and DS.

A 38-year-old woman with DS, hidradenitis suppurativa, and hypothyroidism presented with multiple cutaneous lesions developing over the last year. The lesions continued to increase in number but were otherwise asymptomatic. Physical examination revealed approximately 20 rubbery, pink-tan papules measuring less than 1 cm in diameter that were scattered along the trunk (Figure, A), arms, and legs (Figure, B).

The patient had no known history of immunosuppression or rheumatologic disease and was otherwise healthy. Basic laboratory tests including a complete blood cell count and antinuclear antibody titer were within reference range. The lesions were clinically consistent with dermatofibromas, but due to their increasing number within a short period of time, a biopsy of a representative lesion was performed to confirm the diagnosis.

The exact incidence of MEDFs is unknown, but they are rare, with one review finding only 50 cases reported from 1960 to 2002.⁸ They are increasingly recognized as a sign of potential immune dysregulation. Approximately 56% to 70% of cases are seen in patients with an underlying disease state; 80% are immune mediated.^8,9 Interestingly, DS has long been associated with notable immune dysfunction,^10,11 with evidence suggesting that trisomy 21 may result in widespread changes in gene expression that can lead to interferon activation.¹²

A PubMed search of articles indexed for MEDLINE using the terms dermatofibroma and Down, dermatofibroma and Down syndrome, eruptive dermatofibroma and Down syndrome, and multiple dermatofibroma and Down syndrome revealed 6 cases of MEDFs in patients with DS that have been reported since 2005.^4-7 An additional report by Honda et al¹³ described a patient with DS who developed 7 dermatofibromas, but no time frame of development was specified. We reviewed the characteristics of 8 patients with DS with MEDFs, which included our patient (Table). The average age at time of presentation was 39 years (median age, 40 years). Six patients (75%) were female and 2 (25%) were male. Dermatofibromas were reported to appear over the course of months to years. Comorbidities included psoriatic arthritis (treated with methotrexate),⁶ thyroid disorders (ie, Graves disease),⁶ hypercholesterolemia,⁶ hidradenitis suppurativa, long-standing mild lymphopenia (1.4×10⁹/L [reference range, 1.5−4.0×10⁹/L]),⁴ and acute megakaryoblastic leukemia¹³ treated 15 years before the appearance of dermatofibromas.

Many dermatologic conditions have been reported at increased rates in individuals with DS, including seborrheic dermatitis, alopecia areata, syringomas, elastosis perforans serpiginosa, cutis marmorata, xerosis, and palmoplantar hyperkeratosis.^14,15 Although drawing conclusions about associations between MEDFs and DS is limited by our small sample size, we have reported this case and reviewed existing cases of MEDFs in DS to highlight a potential association that may be underrecognized or underreported. More evidence is needed to determine the strength of the association between MEDFs and DS, but dermatologists should be aware that MEDFs may be an additional skin finding associated with DS that is related to the syndrome’s immune dysregulation.

The sun protection factor (SPF) value indicates to consumers the level of protection that a given sunscreen formulation provides against erythemally effective UV radiation (UVR). ¹ In vivo SPF testing, the gold standard for determining SPF, yields highly variable results and can harm human test participants. ² In vitro SPF testing methodologies have been under development for years but none have (yet) replaced the in vivo test required by national and international regulatory agencies.

Recent European studies have shown strong data to support a highly standardized in vitro method,¹ now under development by the International Organization for Standardization (ISO)—potentially to serve as a new SPF determination standard.^1,3 Academia and industry should follow this example and actively take steps to develop and validate a suitable replacement for in vivo SPF testing.

In Vivo SPF Testing

The in vivo SPF test involves comparing doses of UVR necessary to induce erythema in human participants with and without sunscreen applied.² Although this method has long been the standard for SPF determination, it is associated with the following major disadvantages:

• Cost: The in vivo test is expensive.
• Variability: Results of the test are subject to high interlaboratory variability due to the inherent subjectivity of identifying erythema, the variable skin types of human participants, and other laboratory-dependent factors.² A study found that the average coefficient of variation for SPF values obtained from 3 or 4 laboratories to be 20%—with values exceeding 50% in some cases. With that level of variability, the same sunscreen may be labeled SPF 30, SPF 50, or SPF 50+, thereby posing a health risk to consumers who rely on the accuracy of such claims. In fact, Miksa et al² concluded that “the largest obstacle to a reliable SPF assessment for consumer health is the in vivo SPF test itself.”
• Ethical concerns: Human participants are intentionally exposed to harmful UVR until sunburn is achieved. For that reason, there have been calls to abandon the practice of in vivo testing.¹

Alternatives to In Vivo SPF Testing

There has been international interest in developing in silico and in vitro alternatives to the in vivo SPF test. These options are attractive because they are relatively inexpensive; avoid exposing human participants to harmful UVR; and have the potential to be more accurate and more reproducible than in vivo tests.

In Vitro Protocols—Many such in vitro tests exist; all generally involve applying a layer of sunscreen to an artificial substrate, exposing it to UVR from a solar simulator, and measuring the UVR transmittance through the product and film by spectrophotometry.¹ Prior shortcomings of this method have included suboptimal reproducibility, lack of data on substrate and product properties, and lack of demonstrated equivalency to in vivo SPF testing.⁴

In Silico Protocols—These tests use data on the UV spectra of sunscreen filters, physical characteristics of sunscreen films on skin, and the unique photoinstability of filters to calculate expected UVR transmittance and SPF of sunscreens based on their ingredients.⁵ Reports have shown high correlation with in vivo values. Results are not subject to random error; reproducibility is theoretically perfect.⁵

Regulatory Agencies and In Vitro Testing

In the United States, sunscreens are regulated as over-the-counter drugs. In vivo testing is the only US Food and Drug Administration (FDA)–approved method for determining SPF for labeling purposes.¹ In a 2007 Proposed Rule and a 2011 Final Rule, the FDA stated that in vitro SPF tests were an inadequate alternative to in vivo tests because of their shortcomings.^4,6

Acknowledging the potential benefits of in vitro testing, the FDA wrote that it would consider in vitro alternatives if equivalency to the in vivo test could be proved.⁶ The agency has not published an official stance on in vitro SPF testing since those statements in 2007 and 2011. Of note, the FDA deems in vitro testing sufficient for making claims of broad-spectrum coverage.⁴

In contrast to the regulatory scenario in the United States, Europe regulates sunscreens as cosmetics, and the European Union (EU) has banned animal testing of cosmetics,⁷ which poses a problem for the development of new sunscreens. It is not surprising, therefore, that in 2006 the European Commission (the executive arm of the EU) published a mandate that in vitro SPF testing methods be actively developed due to ethical concerns associated with in vivo methods.⁸ In 2017, the International Organization for Standardization released specific validation criteria for proposed in vitro tests to facilitate the eventual approval of such methods.¹

Progress of In Vitro Methods

In recent years, advances in in vitro SPF testing methods have addressed shortcomings noted previously by the FDA, which has led to notably improved reproducibility of results and correlation with in vivo values, in large part due to strict standardization of protocols,¹ such as tight temperature control of samples, a multisubstrate approach, robotic product application to ensure even distribution, and pre-irradiation of sunscreen samples.

With these improvements, a 2018 study demonstrated an in vitro SPF testing methodology that exceeded published ISO validation criteria for emulsion-type products.¹ This method was found to have low interlaboratory variability and high correlation with in vivo SPF values (Pearson r=0.88). Importantly, the authors noted that the consistency and reliability of in vitro SPF testing requires broad institution of a single unified method.¹

The method described in the 2018 study¹ has been accepted by the ISO Technical Committee and is undergoing further development³; it is expected to be approved by the European Committee for Standardization. After approval, adoption by member nations of the EU will require individual action, representing the next regulatory hurdle for in vitro SPF testing in Europe.

Final Thoughts and Future Steps

Recent data confirm the potential viability of in vitro testing as a primary method of determining SPF values.¹ Although ISO has moved forward with development of this method, the FDA has been quiet on in vitro SPF testing since 2011.⁴ The agency has, however, acknowledged the disadvantages of in vivo broad-spectrum testing, including exposure of human participants to harmful UVR and poor interlaboratory reproducibility.⁶

Given the technical developments and substantial potential benefits of in vitro testing, we believe that it is time for the FDA to revisit this matter. We propose that the FDA take 2 steps toward in vitro testing. First, publish specific validation criteria that would be deemed necessary for approval of such a test, similar to what ISO published in 2017. Second, thoroughly assess new data supporting the viability of available in vitro testing to determine if the FDA’s stated position that in vitro testing is inadequate remains true.

Although these 2 steps will be important to the process, adoption of an in vitro standard will require more than statements from the FDA. Additional funding should be allocated to researchers who are studying in vitro methodologies, and companies that profit from the multibillion-dollar sunscreen industry should be encouraged to invest in the development of more accurate and more ethical alternatives to in vivo SPF testing.

In vitro SPF testing is inexpensive, avoids the moral quandary of intentionally sunburning human participants, and is more reliable than in vivo testing. It is time for the FDA to facilitate the efforts of academia and industry in taking concrete steps toward approval of an in vitro alternative to in vivo SPF testing.

The sun protection factor (SPF) value indicates to consumers the level of protection that a given sunscreen formulation provides against erythemally effective UV radiation (UVR). ¹ In vivo SPF testing, the gold standard for determining SPF, yields highly variable results and can harm human test participants. ² In vitro SPF testing methodologies have been under development for years but none have (yet) replaced the in vivo test required by national and international regulatory agencies.

Recent European studies have shown strong data to support a highly standardized in vitro method,¹ now under development by the International Organization for Standardization (ISO)—potentially to serve as a new SPF determination standard.^1,3 Academia and industry should follow this example and actively take steps to develop and validate a suitable replacement for in vivo SPF testing.

In Vivo SPF Testing

The in vivo SPF test involves comparing doses of UVR necessary to induce erythema in human participants with and without sunscreen applied.² Although this method has long been the standard for SPF determination, it is associated with the following major disadvantages:

• Cost: The in vivo test is expensive.
• Variability: Results of the test are subject to high interlaboratory variability due to the inherent subjectivity of identifying erythema, the variable skin types of human participants, and other laboratory-dependent factors.² A study found that the average coefficient of variation for SPF values obtained from 3 or 4 laboratories to be 20%—with values exceeding 50% in some cases. With that level of variability, the same sunscreen may be labeled SPF 30, SPF 50, or SPF 50+, thereby posing a health risk to consumers who rely on the accuracy of such claims. In fact, Miksa et al² concluded that “the largest obstacle to a reliable SPF assessment for consumer health is the in vivo SPF test itself.”
• Ethical concerns: Human participants are intentionally exposed to harmful UVR until sunburn is achieved. For that reason, there have been calls to abandon the practice of in vivo testing.¹

Alternatives to In Vivo SPF Testing

There has been international interest in developing in silico and in vitro alternatives to the in vivo SPF test. These options are attractive because they are relatively inexpensive; avoid exposing human participants to harmful UVR; and have the potential to be more accurate and more reproducible than in vivo tests.

In Vitro Protocols—Many such in vitro tests exist; all generally involve applying a layer of sunscreen to an artificial substrate, exposing it to UVR from a solar simulator, and measuring the UVR transmittance through the product and film by spectrophotometry.¹ Prior shortcomings of this method have included suboptimal reproducibility, lack of data on substrate and product properties, and lack of demonstrated equivalency to in vivo SPF testing.⁴

In Silico Protocols—These tests use data on the UV spectra of sunscreen filters, physical characteristics of sunscreen films on skin, and the unique photoinstability of filters to calculate expected UVR transmittance and SPF of sunscreens based on their ingredients.⁵ Reports have shown high correlation with in vivo values. Results are not subject to random error; reproducibility is theoretically perfect.⁵

Regulatory Agencies and In Vitro Testing

In the United States, sunscreens are regulated as over-the-counter drugs. In vivo testing is the only US Food and Drug Administration (FDA)–approved method for determining SPF for labeling purposes.¹ In a 2007 Proposed Rule and a 2011 Final Rule, the FDA stated that in vitro SPF tests were an inadequate alternative to in vivo tests because of their shortcomings.^4,6

Acknowledging the potential benefits of in vitro testing, the FDA wrote that it would consider in vitro alternatives if equivalency to the in vivo test could be proved.⁶ The agency has not published an official stance on in vitro SPF testing since those statements in 2007 and 2011. Of note, the FDA deems in vitro testing sufficient for making claims of broad-spectrum coverage.⁴

In contrast to the regulatory scenario in the United States, Europe regulates sunscreens as cosmetics, and the European Union (EU) has banned animal testing of cosmetics,⁷ which poses a problem for the development of new sunscreens. It is not surprising, therefore, that in 2006 the European Commission (the executive arm of the EU) published a mandate that in vitro SPF testing methods be actively developed due to ethical concerns associated with in vivo methods.⁸ In 2017, the International Organization for Standardization released specific validation criteria for proposed in vitro tests to facilitate the eventual approval of such methods.¹

Progress of In Vitro Methods

In recent years, advances in in vitro SPF testing methods have addressed shortcomings noted previously by the FDA, which has led to notably improved reproducibility of results and correlation with in vivo values, in large part due to strict standardization of protocols,¹ such as tight temperature control of samples, a multisubstrate approach, robotic product application to ensure even distribution, and pre-irradiation of sunscreen samples.

With these improvements, a 2018 study demonstrated an in vitro SPF testing methodology that exceeded published ISO validation criteria for emulsion-type products.¹ This method was found to have low interlaboratory variability and high correlation with in vivo SPF values (Pearson r=0.88). Importantly, the authors noted that the consistency and reliability of in vitro SPF testing requires broad institution of a single unified method.¹

The method described in the 2018 study¹ has been accepted by the ISO Technical Committee and is undergoing further development³; it is expected to be approved by the European Committee for Standardization. After approval, adoption by member nations of the EU will require individual action, representing the next regulatory hurdle for in vitro SPF testing in Europe.

Final Thoughts and Future Steps

Recent data confirm the potential viability of in vitro testing as a primary method of determining SPF values.¹ Although ISO has moved forward with development of this method, the FDA has been quiet on in vitro SPF testing since 2011.⁴ The agency has, however, acknowledged the disadvantages of in vivo broad-spectrum testing, including exposure of human participants to harmful UVR and poor interlaboratory reproducibility.⁶

Given the technical developments and substantial potential benefits of in vitro testing, we believe that it is time for the FDA to revisit this matter. We propose that the FDA take 2 steps toward in vitro testing. First, publish specific validation criteria that would be deemed necessary for approval of such a test, similar to what ISO published in 2017. Second, thoroughly assess new data supporting the viability of available in vitro testing to determine if the FDA’s stated position that in vitro testing is inadequate remains true.

Although these 2 steps will be important to the process, adoption of an in vitro standard will require more than statements from the FDA. Additional funding should be allocated to researchers who are studying in vitro methodologies, and companies that profit from the multibillion-dollar sunscreen industry should be encouraged to invest in the development of more accurate and more ethical alternatives to in vivo SPF testing.

In vitro SPF testing is inexpensive, avoids the moral quandary of intentionally sunburning human participants, and is more reliable than in vivo testing. It is time for the FDA to facilitate the efforts of academia and industry in taking concrete steps toward approval of an in vitro alternative to in vivo SPF testing.

The sun protection factor (SPF) value indicates to consumers the level of protection that a given sunscreen formulation provides against erythemally effective UV radiation (UVR). ¹ In vivo SPF testing, the gold standard for determining SPF, yields highly variable results and can harm human test participants. ² In vitro SPF testing methodologies have been under development for years but none have (yet) replaced the in vivo test required by national and international regulatory agencies.

Recent European studies have shown strong data to support a highly standardized in vitro method,¹ now under development by the International Organization for Standardization (ISO)—potentially to serve as a new SPF determination standard.^1,3 Academia and industry should follow this example and actively take steps to develop and validate a suitable replacement for in vivo SPF testing.

In Vivo SPF Testing

The in vivo SPF test involves comparing doses of UVR necessary to induce erythema in human participants with and without sunscreen applied.² Although this method has long been the standard for SPF determination, it is associated with the following major disadvantages:

• Cost: The in vivo test is expensive.
• Variability: Results of the test are subject to high interlaboratory variability due to the inherent subjectivity of identifying erythema, the variable skin types of human participants, and other laboratory-dependent factors.² A study found that the average coefficient of variation for SPF values obtained from 3 or 4 laboratories to be 20%—with values exceeding 50% in some cases. With that level of variability, the same sunscreen may be labeled SPF 30, SPF 50, or SPF 50+, thereby posing a health risk to consumers who rely on the accuracy of such claims. In fact, Miksa et al² concluded that “the largest obstacle to a reliable SPF assessment for consumer health is the in vivo SPF test itself.”
• Ethical concerns: Human participants are intentionally exposed to harmful UVR until sunburn is achieved. For that reason, there have been calls to abandon the practice of in vivo testing.¹

Alternatives to In Vivo SPF Testing

There has been international interest in developing in silico and in vitro alternatives to the in vivo SPF test. These options are attractive because they are relatively inexpensive; avoid exposing human participants to harmful UVR; and have the potential to be more accurate and more reproducible than in vivo tests.

In Vitro Protocols—Many such in vitro tests exist; all generally involve applying a layer of sunscreen to an artificial substrate, exposing it to UVR from a solar simulator, and measuring the UVR transmittance through the product and film by spectrophotometry.¹ Prior shortcomings of this method have included suboptimal reproducibility, lack of data on substrate and product properties, and lack of demonstrated equivalency to in vivo SPF testing.⁴

In Silico Protocols—These tests use data on the UV spectra of sunscreen filters, physical characteristics of sunscreen films on skin, and the unique photoinstability of filters to calculate expected UVR transmittance and SPF of sunscreens based on their ingredients.⁵ Reports have shown high correlation with in vivo values. Results are not subject to random error; reproducibility is theoretically perfect.⁵

Regulatory Agencies and In Vitro Testing

In the United States, sunscreens are regulated as over-the-counter drugs. In vivo testing is the only US Food and Drug Administration (FDA)–approved method for determining SPF for labeling purposes.¹ In a 2007 Proposed Rule and a 2011 Final Rule, the FDA stated that in vitro SPF tests were an inadequate alternative to in vivo tests because of their shortcomings.^4,6

Acknowledging the potential benefits of in vitro testing, the FDA wrote that it would consider in vitro alternatives if equivalency to the in vivo test could be proved.⁶ The agency has not published an official stance on in vitro SPF testing since those statements in 2007 and 2011. Of note, the FDA deems in vitro testing sufficient for making claims of broad-spectrum coverage.⁴

In contrast to the regulatory scenario in the United States, Europe regulates sunscreens as cosmetics, and the European Union (EU) has banned animal testing of cosmetics,⁷ which poses a problem for the development of new sunscreens. It is not surprising, therefore, that in 2006 the European Commission (the executive arm of the EU) published a mandate that in vitro SPF testing methods be actively developed due to ethical concerns associated with in vivo methods.⁸ In 2017, the International Organization for Standardization released specific validation criteria for proposed in vitro tests to facilitate the eventual approval of such methods.¹

Progress of In Vitro Methods

In recent years, advances in in vitro SPF testing methods have addressed shortcomings noted previously by the FDA, which has led to notably improved reproducibility of results and correlation with in vivo values, in large part due to strict standardization of protocols,¹ such as tight temperature control of samples, a multisubstrate approach, robotic product application to ensure even distribution, and pre-irradiation of sunscreen samples.

With these improvements, a 2018 study demonstrated an in vitro SPF testing methodology that exceeded published ISO validation criteria for emulsion-type products.¹ This method was found to have low interlaboratory variability and high correlation with in vivo SPF values (Pearson r=0.88). Importantly, the authors noted that the consistency and reliability of in vitro SPF testing requires broad institution of a single unified method.¹

The method described in the 2018 study¹ has been accepted by the ISO Technical Committee and is undergoing further development³; it is expected to be approved by the European Committee for Standardization. After approval, adoption by member nations of the EU will require individual action, representing the next regulatory hurdle for in vitro SPF testing in Europe.

Final Thoughts and Future Steps

Recent data confirm the potential viability of in vitro testing as a primary method of determining SPF values.¹ Although ISO has moved forward with development of this method, the FDA has been quiet on in vitro SPF testing since 2011.⁴ The agency has, however, acknowledged the disadvantages of in vivo broad-spectrum testing, including exposure of human participants to harmful UVR and poor interlaboratory reproducibility.⁶

Given the technical developments and substantial potential benefits of in vitro testing, we believe that it is time for the FDA to revisit this matter. We propose that the FDA take 2 steps toward in vitro testing. First, publish specific validation criteria that would be deemed necessary for approval of such a test, similar to what ISO published in 2017. Second, thoroughly assess new data supporting the viability of available in vitro testing to determine if the FDA’s stated position that in vitro testing is inadequate remains true.

Although these 2 steps will be important to the process, adoption of an in vitro standard will require more than statements from the FDA. Additional funding should be allocated to researchers who are studying in vitro methodologies, and companies that profit from the multibillion-dollar sunscreen industry should be encouraged to invest in the development of more accurate and more ethical alternatives to in vivo SPF testing.

In vitro SPF testing is inexpensive, avoids the moral quandary of intentionally sunburning human participants, and is more reliable than in vivo testing. It is time for the FDA to facilitate the efforts of academia and industry in taking concrete steps toward approval of an in vitro alternative to in vivo SPF testing.

To the Editor:

There is increasing evidence supporting the use of the human papillomavirus (HPV) vaccine in the treatment of recalcitrant common warts.¹ We describe a potential complication associated with HPV vaccine treatment of warts that would be of interest to dermatologists.

A 70-year-old woman presented with a plantar wart measuring 6 mm in diameter at the base of the right hallux of 5 years’ duration. Prior failed therapies for wart removal included multiple paring treatments, cryotherapy, and topical salicylic acid 40% to 60%. The patient had no notable comorbidities; no history of gout; and no known risk factors for gout, such as hypertension, renal insufficiency, diuretic use, obesity, family history, or trauma.

Prior reports cited effective treatment of recalcitrant warts with recombinant HPV vaccines, both intralesionally¹ and intramuscularly.^2,3 With this knowledge in mind, we administered an intralesional injection with 0.1-mL recombinant HPV 9-valent vaccine to the patient’s plantar wart. Gradual erythema and swelling of the right first metatarsophalangeal joint developed over the next 7 days. Synovial fluid analysis demonstrated negatively birefringent crystals. The patient commenced treatment with colchicine and indomethacin and improved over the next 5 days. The wart resolved 3 months later and required no further treatment.

Prophylactic quadrivalent HPV vaccines have shown efficacy in treating HPV-associated precancerous and cancerous lesions.⁴ Case reports have suggested that HPV vaccines may be an effective treatment option for recalcitrant warts,^1-3,5 especially in cases that do not respond to traditional treatment. It is possible that the mechanism of wart treatment involves overlap in the antigenic epitopes of the HPV types targeted by the vaccine vs the HPV types responsible for causing warts.² Papillomaviruslike particles, based on the L1 capsid protein, can induce a specific CD8⁺ activation signal, leading to a vaccine-induced cytotoxic T-cell response that targets the wart cells with HPV-like antigens.⁶ The HPV vaccine contains aluminium, which has been shown to activate NLRP3 inflammasome,⁵ which may trigger gout by increasing monosodium urate crystal deposition via IL-1β production.⁷ This may lead to an increased risk for gout flares, an adverse effect of the HPV vaccine. This finding is supported by other studies of aluminium-containing vaccines that show an association with gout.⁶ It is noted that these vaccines are mostly delivered intramuscularly or subcutaneously in some cases.

We reported a case of gout triggered by intralesional HPV vaccine treatment of warts. It is unclear whether the gout was induced by the vaccine itself or whether it was due to trauma caused by the intralesional injection near the joint space. Based on our findings, we recommend that patients receiving intralesional injections for wart treatment be advised of this potential adverse effect, especially if they have risk factors for gout or have a history of gout.

To the Editor:

There is increasing evidence supporting the use of the human papillomavirus (HPV) vaccine in the treatment of recalcitrant common warts.¹ We describe a potential complication associated with HPV vaccine treatment of warts that would be of interest to dermatologists.

A 70-year-old woman presented with a plantar wart measuring 6 mm in diameter at the base of the right hallux of 5 years’ duration. Prior failed therapies for wart removal included multiple paring treatments, cryotherapy, and topical salicylic acid 40% to 60%. The patient had no notable comorbidities; no history of gout; and no known risk factors for gout, such as hypertension, renal insufficiency, diuretic use, obesity, family history, or trauma.

Prior reports cited effective treatment of recalcitrant warts with recombinant HPV vaccines, both intralesionally¹ and intramuscularly.^2,3 With this knowledge in mind, we administered an intralesional injection with 0.1-mL recombinant HPV 9-valent vaccine to the patient’s plantar wart. Gradual erythema and swelling of the right first metatarsophalangeal joint developed over the next 7 days. Synovial fluid analysis demonstrated negatively birefringent crystals. The patient commenced treatment with colchicine and indomethacin and improved over the next 5 days. The wart resolved 3 months later and required no further treatment.

Prophylactic quadrivalent HPV vaccines have shown efficacy in treating HPV-associated precancerous and cancerous lesions.⁴ Case reports have suggested that HPV vaccines may be an effective treatment option for recalcitrant warts,^1-3,5 especially in cases that do not respond to traditional treatment. It is possible that the mechanism of wart treatment involves overlap in the antigenic epitopes of the HPV types targeted by the vaccine vs the HPV types responsible for causing warts.² Papillomaviruslike particles, based on the L1 capsid protein, can induce a specific CD8⁺ activation signal, leading to a vaccine-induced cytotoxic T-cell response that targets the wart cells with HPV-like antigens.⁶ The HPV vaccine contains aluminium, which has been shown to activate NLRP3 inflammasome,⁵ which may trigger gout by increasing monosodium urate crystal deposition via IL-1β production.⁷ This may lead to an increased risk for gout flares, an adverse effect of the HPV vaccine. This finding is supported by other studies of aluminium-containing vaccines that show an association with gout.⁶ It is noted that these vaccines are mostly delivered intramuscularly or subcutaneously in some cases.

We reported a case of gout triggered by intralesional HPV vaccine treatment of warts. It is unclear whether the gout was induced by the vaccine itself or whether it was due to trauma caused by the intralesional injection near the joint space. Based on our findings, we recommend that patients receiving intralesional injections for wart treatment be advised of this potential adverse effect, especially if they have risk factors for gout or have a history of gout.

To the Editor:

There is increasing evidence supporting the use of the human papillomavirus (HPV) vaccine in the treatment of recalcitrant common warts.¹ We describe a potential complication associated with HPV vaccine treatment of warts that would be of interest to dermatologists.

A 70-year-old woman presented with a plantar wart measuring 6 mm in diameter at the base of the right hallux of 5 years’ duration. Prior failed therapies for wart removal included multiple paring treatments, cryotherapy, and topical salicylic acid 40% to 60%. The patient had no notable comorbidities; no history of gout; and no known risk factors for gout, such as hypertension, renal insufficiency, diuretic use, obesity, family history, or trauma.

Prior reports cited effective treatment of recalcitrant warts with recombinant HPV vaccines, both intralesionally¹ and intramuscularly.^2,3 With this knowledge in mind, we administered an intralesional injection with 0.1-mL recombinant HPV 9-valent vaccine to the patient’s plantar wart. Gradual erythema and swelling of the right first metatarsophalangeal joint developed over the next 7 days. Synovial fluid analysis demonstrated negatively birefringent crystals. The patient commenced treatment with colchicine and indomethacin and improved over the next 5 days. The wart resolved 3 months later and required no further treatment.

Prophylactic quadrivalent HPV vaccines have shown efficacy in treating HPV-associated precancerous and cancerous lesions.⁴ Case reports have suggested that HPV vaccines may be an effective treatment option for recalcitrant warts,^1-3,5 especially in cases that do not respond to traditional treatment. It is possible that the mechanism of wart treatment involves overlap in the antigenic epitopes of the HPV types targeted by the vaccine vs the HPV types responsible for causing warts.² Papillomaviruslike particles, based on the L1 capsid protein, can induce a specific CD8⁺ activation signal, leading to a vaccine-induced cytotoxic T-cell response that targets the wart cells with HPV-like antigens.⁶ The HPV vaccine contains aluminium, which has been shown to activate NLRP3 inflammasome,⁵ which may trigger gout by increasing monosodium urate crystal deposition via IL-1β production.⁷ This may lead to an increased risk for gout flares, an adverse effect of the HPV vaccine. This finding is supported by other studies of aluminium-containing vaccines that show an association with gout.⁶ It is noted that these vaccines are mostly delivered intramuscularly or subcutaneously in some cases.

We reported a case of gout triggered by intralesional HPV vaccine treatment of warts. It is unclear whether the gout was induced by the vaccine itself or whether it was due to trauma caused by the intralesional injection near the joint space. Based on our findings, we recommend that patients receiving intralesional injections for wart treatment be advised of this potential adverse effect, especially if they have risk factors for gout or have a history of gout.

The Diagnosis: Pachydermoperiostosis

Histopathology of the forehead punch biopsy demonstrated sebaceous hyperplasia with an occupation rate of greater than 40%, increased mucin, elastic fiber degeneration, and fibrosis. Pachydermia is graded from 0 to 3 depending on the degree of these changes; our patient met criteria for grade 3 pachydermia (Figure 1). Radiography revealed diffuse cortical thickening of the long bones that was most marked in the left femur (Figure 2); however, no other findings were demonstrative of Paget disease.

Pachydermoperiostosis (PDP)(also known as Touraine-Solente-Golé syndrome or primary hypertrophic osteoarthropathy) is a rare genetic condition that affects both the dermatologic and skeletal systems. Clinical features of the disease include progressive thickening and furrowing of the skin on the scalp and face (known as pachydermia), digital clubbing, and periostosis. Other potential cutaneous features include seborrhea, acne, hyperhidrosis of the palms and soles, cutis verticis gyrata, eczema, and a burning sensation of the hands and feet. Myelofibrosis and gastrointestinal abnormalities also have been reported.¹

The disease typically affects males (7:1 ratio); also, men typically display a more severe phenotype of the disease.² It most commonly begins during puberty and follows a generally progressive course of 5 to 20 years before eventually stabilizing. Both autosomal-dominant with incomplete penetrance and recessive inheritance versions of PDP can occur. Prostaglandin E₂ (PGE₂) has been implicated in the pathogenesis of PDP; PGE₂ is important in the inflammatory response and may evolve from disrupted protein degradation pathways.³ Sasaki et al⁴ additionally reported that the severity of pachydermia clinically and histologically appeared to correlate with the serum PGE₂ levels in affected patients. Prostaglandin E₂ causes a vasodilatory effect, perhaps explaining the clubbing observed in PDP, and also modifies the activity of osteoblasts and osteoclasts, causing the bone remodeling observed in the disease.⁴

In our patient, the initial differential diagnosis included PDP, as well as lepromatous leprosy, acromegaly, Paget disease of the bone, amyloidosis, scleromyxedema, and cutaneous T-cell lymphoma. However, the time course of the disease, lack of numerous symmetric thickened plaques and madarosis, and pathology argued against lepromatous leprosy. Acromegaly was ruled out due to lack of macroglossia as well as laboratory analysis within reference range including IGF-1 levels and thyroid function tests. Biopsy findings ultimately ruled out amyloidosis and cutaneous T-cell lymphoma. The bone scan revealed diffuse cortical thickening consistent with PDP, and there were no other radiologic findings suggestive of Paget disease. Pachydermoperiostosis is diagnosed using the Borochowitz criteria, which entails that 2 of the following 4 fulfillment criteria must be met: familial transmission, pachydermia, digital clubbing, and/or bony involvement with evidence of radiologic alterations or pain. Our patient met all 4 criteria. The clinical manifestations of PDP are variable with respect to skin and bone changes. The various clinical expressions include the complete form (ie, pachydermia, cutis verticis gyrata, periostosis), the incomplete form (ie, absence of cutis verticis gyrata), and forme fruste (ie, pachydermia with minimal or absent periostosis).⁵

Management for PDP involves surgical correction for cosmesis as well as for functional concerns if present. Symptoms secondary to periostosis should be managed with symptomatic treatment such as nonsteroidal antiinflammatory drugs. Patients managed with etoricoxib, a COX-2–selective nonsteroidal anti-inflammatory drug, have had normalized inflammatory markers that resulted in the lessening of forehead skin folds. Oral aescin has been shown to relieve joint pain due to its antiedematous effect.⁶ Our patient received treatment with nonsteroidal anti-inflammatory drugs for symptomatic management of the associated joint pain but unfortunately was lost to follow-up.

The Diagnosis: Pachydermoperiostosis

Histopathology of the forehead punch biopsy demonstrated sebaceous hyperplasia with an occupation rate of greater than 40%, increased mucin, elastic fiber degeneration, and fibrosis. Pachydermia is graded from 0 to 3 depending on the degree of these changes; our patient met criteria for grade 3 pachydermia (Figure 1). Radiography revealed diffuse cortical thickening of the long bones that was most marked in the left femur (Figure 2); however, no other findings were demonstrative of Paget disease.

Pachydermoperiostosis (PDP)(also known as Touraine-Solente-Golé syndrome or primary hypertrophic osteoarthropathy) is a rare genetic condition that affects both the dermatologic and skeletal systems. Clinical features of the disease include progressive thickening and furrowing of the skin on the scalp and face (known as pachydermia), digital clubbing, and periostosis. Other potential cutaneous features include seborrhea, acne, hyperhidrosis of the palms and soles, cutis verticis gyrata, eczema, and a burning sensation of the hands and feet. Myelofibrosis and gastrointestinal abnormalities also have been reported.¹

The disease typically affects males (7:1 ratio); also, men typically display a more severe phenotype of the disease.² It most commonly begins during puberty and follows a generally progressive course of 5 to 20 years before eventually stabilizing. Both autosomal-dominant with incomplete penetrance and recessive inheritance versions of PDP can occur. Prostaglandin E₂ (PGE₂) has been implicated in the pathogenesis of PDP; PGE₂ is important in the inflammatory response and may evolve from disrupted protein degradation pathways.³ Sasaki et al⁴ additionally reported that the severity of pachydermia clinically and histologically appeared to correlate with the serum PGE₂ levels in affected patients. Prostaglandin E₂ causes a vasodilatory effect, perhaps explaining the clubbing observed in PDP, and also modifies the activity of osteoblasts and osteoclasts, causing the bone remodeling observed in the disease.⁴

In our patient, the initial differential diagnosis included PDP, as well as lepromatous leprosy, acromegaly, Paget disease of the bone, amyloidosis, scleromyxedema, and cutaneous T-cell lymphoma. However, the time course of the disease, lack of numerous symmetric thickened plaques and madarosis, and pathology argued against lepromatous leprosy. Acromegaly was ruled out due to lack of macroglossia as well as laboratory analysis within reference range including IGF-1 levels and thyroid function tests. Biopsy findings ultimately ruled out amyloidosis and cutaneous T-cell lymphoma. The bone scan revealed diffuse cortical thickening consistent with PDP, and there were no other radiologic findings suggestive of Paget disease. Pachydermoperiostosis is diagnosed using the Borochowitz criteria, which entails that 2 of the following 4 fulfillment criteria must be met: familial transmission, pachydermia, digital clubbing, and/or bony involvement with evidence of radiologic alterations or pain. Our patient met all 4 criteria. The clinical manifestations of PDP are variable with respect to skin and bone changes. The various clinical expressions include the complete form (ie, pachydermia, cutis verticis gyrata, periostosis), the incomplete form (ie, absence of cutis verticis gyrata), and forme fruste (ie, pachydermia with minimal or absent periostosis).⁵

Management for PDP involves surgical correction for cosmesis as well as for functional concerns if present. Symptoms secondary to periostosis should be managed with symptomatic treatment such as nonsteroidal antiinflammatory drugs. Patients managed with etoricoxib, a COX-2–selective nonsteroidal anti-inflammatory drug, have had normalized inflammatory markers that resulted in the lessening of forehead skin folds. Oral aescin has been shown to relieve joint pain due to its antiedematous effect.⁶ Our patient received treatment with nonsteroidal anti-inflammatory drugs for symptomatic management of the associated joint pain but unfortunately was lost to follow-up.

The Diagnosis: Pachydermoperiostosis

Histopathology of the forehead punch biopsy demonstrated sebaceous hyperplasia with an occupation rate of greater than 40%, increased mucin, elastic fiber degeneration, and fibrosis. Pachydermia is graded from 0 to 3 depending on the degree of these changes; our patient met criteria for grade 3 pachydermia (Figure 1). Radiography revealed diffuse cortical thickening of the long bones that was most marked in the left femur (Figure 2); however, no other findings were demonstrative of Paget disease.

Pachydermoperiostosis (PDP)(also known as Touraine-Solente-Golé syndrome or primary hypertrophic osteoarthropathy) is a rare genetic condition that affects both the dermatologic and skeletal systems. Clinical features of the disease include progressive thickening and furrowing of the skin on the scalp and face (known as pachydermia), digital clubbing, and periostosis. Other potential cutaneous features include seborrhea, acne, hyperhidrosis of the palms and soles, cutis verticis gyrata, eczema, and a burning sensation of the hands and feet. Myelofibrosis and gastrointestinal abnormalities also have been reported.¹

The disease typically affects males (7:1 ratio); also, men typically display a more severe phenotype of the disease.² It most commonly begins during puberty and follows a generally progressive course of 5 to 20 years before eventually stabilizing. Both autosomal-dominant with incomplete penetrance and recessive inheritance versions of PDP can occur. Prostaglandin E₂ (PGE₂) has been implicated in the pathogenesis of PDP; PGE₂ is important in the inflammatory response and may evolve from disrupted protein degradation pathways.³ Sasaki et al⁴ additionally reported that the severity of pachydermia clinically and histologically appeared to correlate with the serum PGE₂ levels in affected patients. Prostaglandin E₂ causes a vasodilatory effect, perhaps explaining the clubbing observed in PDP, and also modifies the activity of osteoblasts and osteoclasts, causing the bone remodeling observed in the disease.⁴

In our patient, the initial differential diagnosis included PDP, as well as lepromatous leprosy, acromegaly, Paget disease of the bone, amyloidosis, scleromyxedema, and cutaneous T-cell lymphoma. However, the time course of the disease, lack of numerous symmetric thickened plaques and madarosis, and pathology argued against lepromatous leprosy. Acromegaly was ruled out due to lack of macroglossia as well as laboratory analysis within reference range including IGF-1 levels and thyroid function tests. Biopsy findings ultimately ruled out amyloidosis and cutaneous T-cell lymphoma. The bone scan revealed diffuse cortical thickening consistent with PDP, and there were no other radiologic findings suggestive of Paget disease. Pachydermoperiostosis is diagnosed using the Borochowitz criteria, which entails that 2 of the following 4 fulfillment criteria must be met: familial transmission, pachydermia, digital clubbing, and/or bony involvement with evidence of radiologic alterations or pain. Our patient met all 4 criteria. The clinical manifestations of PDP are variable with respect to skin and bone changes. The various clinical expressions include the complete form (ie, pachydermia, cutis verticis gyrata, periostosis), the incomplete form (ie, absence of cutis verticis gyrata), and forme fruste (ie, pachydermia with minimal or absent periostosis).⁵

Management for PDP involves surgical correction for cosmesis as well as for functional concerns if present. Symptoms secondary to periostosis should be managed with symptomatic treatment such as nonsteroidal antiinflammatory drugs. Patients managed with etoricoxib, a COX-2–selective nonsteroidal anti-inflammatory drug, have had normalized inflammatory markers that resulted in the lessening of forehead skin folds. Oral aescin has been shown to relieve joint pain due to its antiedematous effect.⁶ Our patient received treatment with nonsteroidal anti-inflammatory drugs for symptomatic management of the associated joint pain but unfortunately was lost to follow-up.

Acute generalized pustular psoriasis (GPP) is a rare severe variant of psoriasis characterized by the sudden widespread eruption of sterile pustules.^1,2 The cutaneous manifestations of GPP also may be accompanied by signs of systemic inflammation, including fever, malaise, and leukocytosis.² Complications are common and may be life-threatening, especially in older patients with comorbid diseases.³ Generalized pustular psoriasis most commonly occurs in patients with a preceding history of psoriasis, but it also may occur de novo.⁴ Generalized pustular psoriasis is associated with notable morbidity and mortality, and relapses are common.^3,4 Many triggers of GPP have been identified, including initiation and withdrawal of various medications, infections, pregnancy, and other conditions.^5,6 Although GPP most often occurs in adults, it also may arise in children and infants.³ In pregnancy, GPP is referred to as impetigo herpetiformis, despite having no etiologic ties with either herpes simplex virus or staphylococcal or streptococcal infection. Impetigo herpetiformis is considered one of the most dangerous dermatoses of pregnancy because of high rates of associated maternal and fetal morbidity.^6,7

Acute GPP has proven to be a challenging disease to treat due to the rarity and relapsing-remitting nature of the disease; additionally, there are relatively few randomized controlled trials investigating the efficacy and safety of treatments for GPP. This review summarizes the features of GPP, including the pathophysiology of the disease, clinical and histological manifestations, and recommendations for management based on a PubMed search of articles indexed for MEDLINE using MeSH terms pertaining to the disease, including generalized pustular psoriasis, impetigo herpetiformis, and von Zumbusch psoriasis.

Pathophysiology

The pathophysiology of GPP is only partially understood, but it is thought to have a distinct pattern of immune activation compared with plaque psoriasis.⁸ Although there is a considerable amount of overlap and cross-talk among cytokine pathways, GPP generally is driven by innate immunity and unrestrained IL-36 cytokine activity. In contrast, adaptive immune responses—namely the tumor necrosis factor (TNF) α, IL-23, IL-17, and IL-22 axes—underlie plaque psoriasis.^8-10

Proinflammatory IL-36 cytokines α, β, and γ, which are all part of the IL-1 superfamily, bind to the IL-36 receptor (IL-36R) to recruit and activate immune cells via various mediators, including IL-1β; IL-8; and chemokines CXCL1, CXCL2, and CXCL8.³ The IL-36 receptor antagonist (IL-36ra) acts to inhibit this inflammatory cascade.^3,8 Microarray analyses of skin biopsy samples have shown that overexpression of IL-17A, TNF-α, IL-1, and IL-36 are seen in both GPP and plaque psoriasis lesions, but GPP lesions had higher expression of IL-1β, IL-36α, and IL-36γ and elevated neutrophil chemokines—CXCL1, CXCL2, and CXCL8—compared with plaque psoriasis lesions.⁸

Gene Mutations Associated With GPP

There are 3 gene mutations that have been associated with pustular variants of psoriasis, though these mutations account for a minority of cases of GPP.⁴ Genetic screenings are not routinely indicated in patients with GPP, but they may be warranted in severe cases when a familial pattern of inheritance is suspected.⁴

IL36RN—The gene IL36RN codes the anti-inflammatory IL-36ra. Loss-of-function mutations in IL36RN lead to impairment of IL-36ra and consequently hyperactivity of the proinflammatory responses triggered by IL-36.³ Homozygous and heterozygous mutations in IL36RN have been observed in both familial and sporadic cases of GPP.^11-13 Subsequent retrospective analyses have identified the presence of IL36RN mutations in patients with GPP with frequencies ranging from 23% to 37%.^14-17IL36RN mutations are thought to be more common in patients without concomitant plaque psoriasis and have been associated with severe disease and early disease onset.¹⁵

CARD14—A gain-of-function mutation in CARD14 results in overactivation of the proinflammatory nuclear factor κB pathway and has been implicated in cases of GPP with concurrent psoriasis vulgaris. Interestingly, this may suggest distinct etiologies underlying GPP de novo and GPP in patients with a history of psoriasis.^18,19

AP1S3—A loss-of-function mutation in AP1S3 results in abnormal endosomal trafficking and autophagy as well as increased expression of IL-36α.^20,21

Clinical Presentation and DiagnosisCutaneous Manifestations of GPP

Generalized pustular psoriasis is characterized by the onset of widespread 2- to 3-mm sterile pustules on erythematous skin or within psoriasiform plaques⁴ (Figure). In patients with skin of color, the erythema may appear less obvious or perhaps slightly violaceous compared to White skin. Pustules may coalesce to form “lakes” of pus.⁵ Cutaneous symptoms include pain, burning, and pruritus. Associated mucosal findings may include cheilitis, geographic tongue, conjunctivitis, and uveitis.⁴

The severity of symptoms can vary greatly among patients as well as between flares within the same patient.^2,3 Four distinct patterns of GPP have been described. The von Zumbusch pattern is characterized by a rapid, generalized, painful, erythematous and pustular eruption accompanied by fever and asthenia. The pustules usually resolve after several days with extensive scaling. The annular pattern is characterized by annular, erythematous, scaly lesions with pustules present centrifugally. The lesions enlarge by centrifugal expansion over a period of hours to days, while healing occurs centrally. The exanthematic type is an acute eruption of small pustules that abruptly appear and disappear within a few days, usually from infection or medication initiation. Sometimes pustules appear within or at the edge of existing psoriatic plaques in a localized pattern—the fourth pattern—often following the exposure to irritants (eg, tars, anthralin).⁵

Impetigo Herpetiformis—Impetigo herpetiformis is a form of GPP associated with pregnancy. It generally presents early in the third trimester with symmetric erythematous plaques in flexural and intertriginous areas with pustules present at lesion margins. Lesions expand centrifugally, with pustulation present at the advancing edge.^6,7 Patients often are acutely ill with fever, delirium, vomiting, and tetany. Mucous membranes, including the tongue, mouth, and esophagus, also may be involved. The eruption typically resolves after delivery, though it often recurs with subsequent pregnancies, with the morbidity risk rising with each successive pregnancy.⁷

Systemic and Extracutaneous Manifestations of GPP

Although the severity of GPP is highly variable, skin manifestations often are accompanied by systemic manifestations of inflammation, including fever and malaise. Common laboratory abnormalities include leukocytosis with peripheral neutrophilia, a high serum C-reactive protein level, hypocalcemia, and hypoalbuminemia.²² Abnormal liver enzymes often are present and result from neutrophilic cholangitis, with alternating strictures and dilations of biliary ducts observed on magnetic resonance imaging.²³ Additional laboratory abnormalities are provided in Table 2. Other extracutaneous findings associated with GPP include arthralgia, edema, and characteristic psoriatic nail changes.⁴ Fatal complications include acute respiratory distress syndrome, renal dysfunction, cardiovascular shock, and sepsis.^24,25

Histologic Features

Given the potential for the skin manifestations of GPP to mimic other disorders, a skin biopsy is warranted to confirm the diagnosis. Generalized pustular psoriasis is histologically characterized by the presence of subcorneal macropustules (ie, spongiform pustules of Kogoj) formed by neutrophil infiltration into the spongelike network of the epidermis.⁶ Otherwise, the architecture of the epithelium in GPP is similar to that seen with plaque psoriasis, with parakeratosis, acanthosis, rete-ridge elongation, diminished stratum granulosum, and thinning of the suprapapillary epidermis, though the inflammatory cell infiltrate and edema are markedly more severe in GPP than plaque psoriasis.^3,4

Differential Diagnosis

There are many other cutaneous pustular diagnoses that must be ruled out when evaluating a patient with GPP (Table 1).²⁶ Acute generalized exanthematous pustulosis (AGEP) is a common mimicker of GPP that is differentiated histologically by the presence of eosinophils and necrotic keratinocytes.⁴ In addition to its distinct histopathologic findings, AGEP is classically associated with recent initiation of certain medications, most commonly penicillins, macrolides, quinolones, sulfonamides, terbinafine, and diltiazem.²⁷ In contrast, GPP more commonly is related to withdrawal of corticosteroids as well as initiation of some biologic medications, including anti-TNF agents.³ Generalized pustular psoriasis should be suspected over AGEP in patients with a personal or family history of psoriasis, though GPP may arise in patients with or without a history of psoriasis. Acute generalized exanthematous pustulosis usually is more abrupt in both onset and resolution compared with GPP, with clearance of pustules within a few days to weeks following cessation of the triggering factor.⁴

Other pustular variants of psoriasis (eg, palmoplantar pustular psoriasis, acrodermatitis continua of Hallopeau) are differentiated from GPP by their chronicity and localization to palmoplantar and/or ungual surfaces.⁵ Other differential diagnoses are listed in Table 1.

Diagnostic Criteria for GPP

Diagnostic criteria have been proposed for GPP (Table 2), including (1) the presence of sterile pustules, (2) systemic signs of inflammation, (3) laboratory abnormalities, (4) histopathologic confirmation of spongiform pustules of Kogoj, and (5) recurrence of symptoms.²² To definitively diagnose GPP, all 5 criteria must be met. To rule out mimickers, it may be worthwhile to perform Gram staining, potassium hydroxide preparation, in vitro cultures, and/or immunofluorescence testing.⁶

Treatment

Given the high potential for mortality associated with GPP, the most essential component of management is to ensure adequate supportive care. Any temperature, fluid, or electrolyte imbalances should be corrected as they arise. Secondary infections also must be identified and treated, if present, to reduce the risk for fatal complications, including systemic infection and sepsis. Precautions must be taken to ensure that serious end-organ damage, including hepatic, renal, and respiratory dysfunction, is avoided.

Adjunctive topical intervention often is initiated with bland emollients, corticosteroids, calcineurin inhibitors, and/or vitamin D derivatives to help soothe skin symptoms, but treatment with systemic therapies usually is warranted to achieve symptom control.^2,25 Importantly, there are no systemic or topical agents that have specifically been approved for the treatment of GPP in Europe or the United States.³ Given the absence of universally accepted treatment guidelines, therapeutic agents for GPP usually are selected based on clinical experience while also taking the extent of involvement and disease severity into consideration.³

Treatment Recommendations for Adults

Oral Systemic Agents—Treatment guidelines set forth by the National Psoriasis Foundation (NPF) in 2012 proposed that first-line therapies for GPP should be acitretin, cyclosporine, methotrexate, and infliximab.²⁸ However, since those guidelines were established, many new biologic therapies have been approved for the treatment of psoriasis and often are considered in the treatment of psoriasis subtypes, including GPP.²⁹ Although retinoids previously were considered to be a preferred first-line therapy, they are associated with a high incidence of adverse effects and must be used with caution in women of childbearing age.⁶ Oral acitretin at a dosage of 0.75 to 1.0 mg/kg/d has been shown to result in clinical improvement within 1 to 2 weeks, and a maintenance dosage of 0.125 to 0.25 mg/kg/d is required for several months to prevent recurrence.³⁰ Methotrexate—5.0 to 15.0 mg/wk, or perhaps higher in patients with refractory disease, increased by 2.5-mg intervals until symptoms improve—is recommended by the NPF in patients who are unresponsive or cannot tolerate retinoids, though close monitoring for hematologic abnormalities is required. Cyclosporine 2.5 to 5.0 mg/kg/d is considered an alternative to methotrexate and retinoids; it has a faster onset of action, with improvement reported as early as 2 weeks after initiation of therapy.^1,28 Although cyclosporine may be effective in the acute phase, especially in severe cases of GPP, long-term use of cyclosporine is not recommended because of the potential for renal dysfunction and hypertension.³¹

Biologic Agents—More recent evidence has accumulated supporting the efficacy of anti-TNF agents in the treatment of GPP, suggesting the positioning of these agents as first line. A number of case series have shown dramatic and rapid improvement of GPP with intravenous infliximab 3 to 5 mg/kg, with results observed hours to days after the first infusion.^32-37 Thus, infliximab is recommended as first-line treatment in severe acute cases, though its efficacy as a maintenance therapy has not been sufficiently investigated.⁶ Case reports and case series document the safety and efficacy of adalimumab 40 to 80 mg every 1 to 2 weeks^38,39 and etanercept 25 to 50 mg twice weekly^40-42 in patients with recalcitrantGPP. Therefore, these anti-TNF agents may be considered in patients who are nonresponsive to treatment with infliximab.

Rarely, there have been reports of paradoxical induction of GPP with the use of some anti-TNF agents,^43-45 which may be due to a cytokine imbalance characterized by unopposed IFN-α activation.⁶ In patients with a history of GPP after initiation of a biologic, treatment with agents from within the offending class should be avoided.

The IL-17A monoclonal antibodies secukinumab, ixekizumab, and brodalumab have been shown in open-label phase 3 studies to result in disease remission at 12 weeks.^46-48 Treatment with guselkumab, an IL-23 monoclonal antibody, also has demonstrated efficacy in patients with GPP.⁴⁹ Ustekinumab, an IL-12/23 inhibitor, in combination with acitretin also has been shown to be successful in achieving disease remission after a few weeks of treatment.⁵⁰

More recent case reports have shown the efficacy of IL-1 inhibitors including gevokizumab, canakinumab, and anakinra in achieving GPP clearance, though more prospective studies are needed to evaluate their efficacy.^51-53 Given the etiologic association between IL-1 disinhibition and GPP, future investigations of these therapies as well as those that target the IL-36 pathway may prove to be particularly interesting.

Phototherapy and Combination Therapies—Phototherapy may be considered as maintenance therapy after disease control is achieved, though it is not considered appropriate for acute cases.²⁸ Combination therapies with a biologic plus a nonbiologic systemic agent or alternating among various biologics may allow physicians to maximize benefits and minimize adverse effects in the long term, though there is insufficient evidence to suggest any specific combination treatment algorithm for GPP.²⁸

Treatment Recommendations for Pediatric Patients

Based on a small number of case series and case reports, the first-line treatment strategy for children with GPP is similar to adults. Given the notable adverse events of most oral systemic agents, biologic therapies may emerge as first-line therapy in the pediatric population as more evidence accumulates.²⁸

Treatment Recommendations for Pregnant Patients

Systemic corticosteroids are widely considered to be the first-line treatments for the management of impetigo herpetiformis.⁷ Low-dose prednisone (15–30 mg/d) usually is effective, but severe cases may require increasing the dosage to 60 mg/d.⁶ Given the potential for rebound flares upon withdrawal of systemic corticosteroids, these agents must be gradually tapered after the resolution of symptoms.

Certolizumab pegol also is an attractive option in pregnant patients with impetigo herpetiformis because of its favorable safety profile and negligible mother-to-infant transfer through the placenta or breast milk. It has been shown to be effective in treating GPP and impetigo herpetiformis during pregnancy in recently published case reports.^54,55 In refractory cases, other TNF-α inhibitors (eg, adalimumab, infliximab, etanercept) or cyclosporine may be considered. However, cautious medical monitoring is warranted, as little is known about the potential adverse effects of these agents to the mother and fetus.^28,56 Data from transplant recipients along with several case reports indicate that cyclosporine is not associated with an increased risk for adverse effects during pregnancy at a dose of 2 to 3 mg/kg.^57-59 Both methotrexate and retinoids are known teratogens and are therefore contraindicated in pregnant patients.⁵⁶

If pustules do not resolve in the postpartum period, patients should be treated with standard GPP therapies. However, long-term and population studies are lacking regarding the potential for infant exposure to systemic agents in breast milk. Therefore, the NPF recommends avoiding breastfeeding while taking systemic medications, if possible.⁵⁶

Limitations of Treatment Recommendations

The ability to generate an evidence-based treatment strategy for GPP is limited by a lack of high-quality studies investigating the efficacy and safety of treatments in patients with GPP due to the rarity and relapsing-remitting nature of the disease, which makes randomized controlled trials difficult to conduct. The quality of the available research is further limited by the lack of validated outcome measures to specifically assess improvements in patients with GPP, such that results are difficult to synthesize and compare among studies.³¹

Conclusion

Although limited, the available research suggests that treatment with various biologics, especially infliximab, is effective in achieving rapid clearance in patients with GPP. In general, biologics may be the most appropriate treatment option in patients with GPP given their relatively favorable safety profiles. Other oral systemic agents, including acitretin, cyclosporine, and methotrexate, have limited evidence to support their use in the acute phase, but their safety profiles often limit their utility in the long-term. Emerging evidence regarding the association of GPP with IL36RN mutations suggests a unique role for agents targeting the IL-36 or IL-1 pathways, though this has yet to be thoroughly investigated.

Acute generalized pustular psoriasis (GPP) is a rare severe variant of psoriasis characterized by the sudden widespread eruption of sterile pustules.^1,2 The cutaneous manifestations of GPP also may be accompanied by signs of systemic inflammation, including fever, malaise, and leukocytosis.² Complications are common and may be life-threatening, especially in older patients with comorbid diseases.³ Generalized pustular psoriasis most commonly occurs in patients with a preceding history of psoriasis, but it also may occur de novo.⁴ Generalized pustular psoriasis is associated with notable morbidity and mortality, and relapses are common.^3,4 Many triggers of GPP have been identified, including initiation and withdrawal of various medications, infections, pregnancy, and other conditions.^5,6 Although GPP most often occurs in adults, it also may arise in children and infants.³ In pregnancy, GPP is referred to as impetigo herpetiformis, despite having no etiologic ties with either herpes simplex virus or staphylococcal or streptococcal infection. Impetigo herpetiformis is considered one of the most dangerous dermatoses of pregnancy because of high rates of associated maternal and fetal morbidity.^6,7

Acute GPP has proven to be a challenging disease to treat due to the rarity and relapsing-remitting nature of the disease; additionally, there are relatively few randomized controlled trials investigating the efficacy and safety of treatments for GPP. This review summarizes the features of GPP, including the pathophysiology of the disease, clinical and histological manifestations, and recommendations for management based on a PubMed search of articles indexed for MEDLINE using MeSH terms pertaining to the disease, including generalized pustular psoriasis, impetigo herpetiformis, and von Zumbusch psoriasis.

Pathophysiology

The pathophysiology of GPP is only partially understood, but it is thought to have a distinct pattern of immune activation compared with plaque psoriasis.⁸ Although there is a considerable amount of overlap and cross-talk among cytokine pathways, GPP generally is driven by innate immunity and unrestrained IL-36 cytokine activity. In contrast, adaptive immune responses—namely the tumor necrosis factor (TNF) α, IL-23, IL-17, and IL-22 axes—underlie plaque psoriasis.^8-10

Proinflammatory IL-36 cytokines α, β, and γ, which are all part of the IL-1 superfamily, bind to the IL-36 receptor (IL-36R) to recruit and activate immune cells via various mediators, including IL-1β; IL-8; and chemokines CXCL1, CXCL2, and CXCL8.³ The IL-36 receptor antagonist (IL-36ra) acts to inhibit this inflammatory cascade.^3,8 Microarray analyses of skin biopsy samples have shown that overexpression of IL-17A, TNF-α, IL-1, and IL-36 are seen in both GPP and plaque psoriasis lesions, but GPP lesions had higher expression of IL-1β, IL-36α, and IL-36γ and elevated neutrophil chemokines—CXCL1, CXCL2, and CXCL8—compared with plaque psoriasis lesions.⁸

Gene Mutations Associated With GPP

There are 3 gene mutations that have been associated with pustular variants of psoriasis, though these mutations account for a minority of cases of GPP.⁴ Genetic screenings are not routinely indicated in patients with GPP, but they may be warranted in severe cases when a familial pattern of inheritance is suspected.⁴

IL36RN—The gene IL36RN codes the anti-inflammatory IL-36ra. Loss-of-function mutations in IL36RN lead to impairment of IL-36ra and consequently hyperactivity of the proinflammatory responses triggered by IL-36.³ Homozygous and heterozygous mutations in IL36RN have been observed in both familial and sporadic cases of GPP.^11-13 Subsequent retrospective analyses have identified the presence of IL36RN mutations in patients with GPP with frequencies ranging from 23% to 37%.^14-17IL36RN mutations are thought to be more common in patients without concomitant plaque psoriasis and have been associated with severe disease and early disease onset.¹⁵

CARD14—A gain-of-function mutation in CARD14 results in overactivation of the proinflammatory nuclear factor κB pathway and has been implicated in cases of GPP with concurrent psoriasis vulgaris. Interestingly, this may suggest distinct etiologies underlying GPP de novo and GPP in patients with a history of psoriasis.^18,19

AP1S3—A loss-of-function mutation in AP1S3 results in abnormal endosomal trafficking and autophagy as well as increased expression of IL-36α.^20,21

Clinical Presentation and DiagnosisCutaneous Manifestations of GPP

Generalized pustular psoriasis is characterized by the onset of widespread 2- to 3-mm sterile pustules on erythematous skin or within psoriasiform plaques⁴ (Figure). In patients with skin of color, the erythema may appear less obvious or perhaps slightly violaceous compared to White skin. Pustules may coalesce to form “lakes” of pus.⁵ Cutaneous symptoms include pain, burning, and pruritus. Associated mucosal findings may include cheilitis, geographic tongue, conjunctivitis, and uveitis.⁴

The severity of symptoms can vary greatly among patients as well as between flares within the same patient.^2,3 Four distinct patterns of GPP have been described. The von Zumbusch pattern is characterized by a rapid, generalized, painful, erythematous and pustular eruption accompanied by fever and asthenia. The pustules usually resolve after several days with extensive scaling. The annular pattern is characterized by annular, erythematous, scaly lesions with pustules present centrifugally. The lesions enlarge by centrifugal expansion over a period of hours to days, while healing occurs centrally. The exanthematic type is an acute eruption of small pustules that abruptly appear and disappear within a few days, usually from infection or medication initiation. Sometimes pustules appear within or at the edge of existing psoriatic plaques in a localized pattern—the fourth pattern—often following the exposure to irritants (eg, tars, anthralin).⁵

Impetigo Herpetiformis—Impetigo herpetiformis is a form of GPP associated with pregnancy. It generally presents early in the third trimester with symmetric erythematous plaques in flexural and intertriginous areas with pustules present at lesion margins. Lesions expand centrifugally, with pustulation present at the advancing edge.^6,7 Patients often are acutely ill with fever, delirium, vomiting, and tetany. Mucous membranes, including the tongue, mouth, and esophagus, also may be involved. The eruption typically resolves after delivery, though it often recurs with subsequent pregnancies, with the morbidity risk rising with each successive pregnancy.⁷

Systemic and Extracutaneous Manifestations of GPP

Although the severity of GPP is highly variable, skin manifestations often are accompanied by systemic manifestations of inflammation, including fever and malaise. Common laboratory abnormalities include leukocytosis with peripheral neutrophilia, a high serum C-reactive protein level, hypocalcemia, and hypoalbuminemia.²² Abnormal liver enzymes often are present and result from neutrophilic cholangitis, with alternating strictures and dilations of biliary ducts observed on magnetic resonance imaging.²³ Additional laboratory abnormalities are provided in Table 2. Other extracutaneous findings associated with GPP include arthralgia, edema, and characteristic psoriatic nail changes.⁴ Fatal complications include acute respiratory distress syndrome, renal dysfunction, cardiovascular shock, and sepsis.^24,25

Histologic Features

Given the potential for the skin manifestations of GPP to mimic other disorders, a skin biopsy is warranted to confirm the diagnosis. Generalized pustular psoriasis is histologically characterized by the presence of subcorneal macropustules (ie, spongiform pustules of Kogoj) formed by neutrophil infiltration into the spongelike network of the epidermis.⁶ Otherwise, the architecture of the epithelium in GPP is similar to that seen with plaque psoriasis, with parakeratosis, acanthosis, rete-ridge elongation, diminished stratum granulosum, and thinning of the suprapapillary epidermis, though the inflammatory cell infiltrate and edema are markedly more severe in GPP than plaque psoriasis.^3,4

Differential Diagnosis

There are many other cutaneous pustular diagnoses that must be ruled out when evaluating a patient with GPP (Table 1).²⁶ Acute generalized exanthematous pustulosis (AGEP) is a common mimicker of GPP that is differentiated histologically by the presence of eosinophils and necrotic keratinocytes.⁴ In addition to its distinct histopathologic findings, AGEP is classically associated with recent initiation of certain medications, most commonly penicillins, macrolides, quinolones, sulfonamides, terbinafine, and diltiazem.²⁷ In contrast, GPP more commonly is related to withdrawal of corticosteroids as well as initiation of some biologic medications, including anti-TNF agents.³ Generalized pustular psoriasis should be suspected over AGEP in patients with a personal or family history of psoriasis, though GPP may arise in patients with or without a history of psoriasis. Acute generalized exanthematous pustulosis usually is more abrupt in both onset and resolution compared with GPP, with clearance of pustules within a few days to weeks following cessation of the triggering factor.⁴

Other pustular variants of psoriasis (eg, palmoplantar pustular psoriasis, acrodermatitis continua of Hallopeau) are differentiated from GPP by their chronicity and localization to palmoplantar and/or ungual surfaces.⁵ Other differential diagnoses are listed in Table 1.

Diagnostic Criteria for GPP

Diagnostic criteria have been proposed for GPP (Table 2), including (1) the presence of sterile pustules, (2) systemic signs of inflammation, (3) laboratory abnormalities, (4) histopathologic confirmation of spongiform pustules of Kogoj, and (5) recurrence of symptoms.²² To definitively diagnose GPP, all 5 criteria must be met. To rule out mimickers, it may be worthwhile to perform Gram staining, potassium hydroxide preparation, in vitro cultures, and/or immunofluorescence testing.⁶

Treatment

Given the high potential for mortality associated with GPP, the most essential component of management is to ensure adequate supportive care. Any temperature, fluid, or electrolyte imbalances should be corrected as they arise. Secondary infections also must be identified and treated, if present, to reduce the risk for fatal complications, including systemic infection and sepsis. Precautions must be taken to ensure that serious end-organ damage, including hepatic, renal, and respiratory dysfunction, is avoided.

Adjunctive topical intervention often is initiated with bland emollients, corticosteroids, calcineurin inhibitors, and/or vitamin D derivatives to help soothe skin symptoms, but treatment with systemic therapies usually is warranted to achieve symptom control.^2,25 Importantly, there are no systemic or topical agents that have specifically been approved for the treatment of GPP in Europe or the United States.³ Given the absence of universally accepted treatment guidelines, therapeutic agents for GPP usually are selected based on clinical experience while also taking the extent of involvement and disease severity into consideration.³

Treatment Recommendations for Adults

Oral Systemic Agents—Treatment guidelines set forth by the National Psoriasis Foundation (NPF) in 2012 proposed that first-line therapies for GPP should be acitretin, cyclosporine, methotrexate, and infliximab.²⁸ However, since those guidelines were established, many new biologic therapies have been approved for the treatment of psoriasis and often are considered in the treatment of psoriasis subtypes, including GPP.²⁹ Although retinoids previously were considered to be a preferred first-line therapy, they are associated with a high incidence of adverse effects and must be used with caution in women of childbearing age.⁶ Oral acitretin at a dosage of 0.75 to 1.0 mg/kg/d has been shown to result in clinical improvement within 1 to 2 weeks, and a maintenance dosage of 0.125 to 0.25 mg/kg/d is required for several months to prevent recurrence.³⁰ Methotrexate—5.0 to 15.0 mg/wk, or perhaps higher in patients with refractory disease, increased by 2.5-mg intervals until symptoms improve—is recommended by the NPF in patients who are unresponsive or cannot tolerate retinoids, though close monitoring for hematologic abnormalities is required. Cyclosporine 2.5 to 5.0 mg/kg/d is considered an alternative to methotrexate and retinoids; it has a faster onset of action, with improvement reported as early as 2 weeks after initiation of therapy.^1,28 Although cyclosporine may be effective in the acute phase, especially in severe cases of GPP, long-term use of cyclosporine is not recommended because of the potential for renal dysfunction and hypertension.³¹

Biologic Agents—More recent evidence has accumulated supporting the efficacy of anti-TNF agents in the treatment of GPP, suggesting the positioning of these agents as first line. A number of case series have shown dramatic and rapid improvement of GPP with intravenous infliximab 3 to 5 mg/kg, with results observed hours to days after the first infusion.^32-37 Thus, infliximab is recommended as first-line treatment in severe acute cases, though its efficacy as a maintenance therapy has not been sufficiently investigated.⁶ Case reports and case series document the safety and efficacy of adalimumab 40 to 80 mg every 1 to 2 weeks^38,39 and etanercept 25 to 50 mg twice weekly^40-42 in patients with recalcitrantGPP. Therefore, these anti-TNF agents may be considered in patients who are nonresponsive to treatment with infliximab.

Rarely, there have been reports of paradoxical induction of GPP with the use of some anti-TNF agents,^43-45 which may be due to a cytokine imbalance characterized by unopposed IFN-α activation.⁶ In patients with a history of GPP after initiation of a biologic, treatment with agents from within the offending class should be avoided.

The IL-17A monoclonal antibodies secukinumab, ixekizumab, and brodalumab have been shown in open-label phase 3 studies to result in disease remission at 12 weeks.^46-48 Treatment with guselkumab, an IL-23 monoclonal antibody, also has demonstrated efficacy in patients with GPP.⁴⁹ Ustekinumab, an IL-12/23 inhibitor, in combination with acitretin also has been shown to be successful in achieving disease remission after a few weeks of treatment.⁵⁰

More recent case reports have shown the efficacy of IL-1 inhibitors including gevokizumab, canakinumab, and anakinra in achieving GPP clearance, though more prospective studies are needed to evaluate their efficacy.^51-53 Given the etiologic association between IL-1 disinhibition and GPP, future investigations of these therapies as well as those that target the IL-36 pathway may prove to be particularly interesting.

Phototherapy and Combination Therapies—Phototherapy may be considered as maintenance therapy after disease control is achieved, though it is not considered appropriate for acute cases.²⁸ Combination therapies with a biologic plus a nonbiologic systemic agent or alternating among various biologics may allow physicians to maximize benefits and minimize adverse effects in the long term, though there is insufficient evidence to suggest any specific combination treatment algorithm for GPP.²⁸

Treatment Recommendations for Pediatric Patients

Based on a small number of case series and case reports, the first-line treatment strategy for children with GPP is similar to adults. Given the notable adverse events of most oral systemic agents, biologic therapies may emerge as first-line therapy in the pediatric population as more evidence accumulates.²⁸

Treatment Recommendations for Pregnant Patients

Systemic corticosteroids are widely considered to be the first-line treatments for the management of impetigo herpetiformis.⁷ Low-dose prednisone (15–30 mg/d) usually is effective, but severe cases may require increasing the dosage to 60 mg/d.⁶ Given the potential for rebound flares upon withdrawal of systemic corticosteroids, these agents must be gradually tapered after the resolution of symptoms.

Certolizumab pegol also is an attractive option in pregnant patients with impetigo herpetiformis because of its favorable safety profile and negligible mother-to-infant transfer through the placenta or breast milk. It has been shown to be effective in treating GPP and impetigo herpetiformis during pregnancy in recently published case reports.^54,55 In refractory cases, other TNF-α inhibitors (eg, adalimumab, infliximab, etanercept) or cyclosporine may be considered. However, cautious medical monitoring is warranted, as little is known about the potential adverse effects of these agents to the mother and fetus.^28,56 Data from transplant recipients along with several case reports indicate that cyclosporine is not associated with an increased risk for adverse effects during pregnancy at a dose of 2 to 3 mg/kg.^57-59 Both methotrexate and retinoids are known teratogens and are therefore contraindicated in pregnant patients.⁵⁶

If pustules do not resolve in the postpartum period, patients should be treated with standard GPP therapies. However, long-term and population studies are lacking regarding the potential for infant exposure to systemic agents in breast milk. Therefore, the NPF recommends avoiding breastfeeding while taking systemic medications, if possible.⁵⁶

Limitations of Treatment Recommendations

The ability to generate an evidence-based treatment strategy for GPP is limited by a lack of high-quality studies investigating the efficacy and safety of treatments in patients with GPP due to the rarity and relapsing-remitting nature of the disease, which makes randomized controlled trials difficult to conduct. The quality of the available research is further limited by the lack of validated outcome measures to specifically assess improvements in patients with GPP, such that results are difficult to synthesize and compare among studies.³¹

Conclusion

Although limited, the available research suggests that treatment with various biologics, especially infliximab, is effective in achieving rapid clearance in patients with GPP. In general, biologics may be the most appropriate treatment option in patients with GPP given their relatively favorable safety profiles. Other oral systemic agents, including acitretin, cyclosporine, and methotrexate, have limited evidence to support their use in the acute phase, but their safety profiles often limit their utility in the long-term. Emerging evidence regarding the association of GPP with IL36RN mutations suggests a unique role for agents targeting the IL-36 or IL-1 pathways, though this has yet to be thoroughly investigated.

Acute generalized pustular psoriasis (GPP) is a rare severe variant of psoriasis characterized by the sudden widespread eruption of sterile pustules.^1,2 The cutaneous manifestations of GPP also may be accompanied by signs of systemic inflammation, including fever, malaise, and leukocytosis.² Complications are common and may be life-threatening, especially in older patients with comorbid diseases.³ Generalized pustular psoriasis most commonly occurs in patients with a preceding history of psoriasis, but it also may occur de novo.⁴ Generalized pustular psoriasis is associated with notable morbidity and mortality, and relapses are common.^3,4 Many triggers of GPP have been identified, including initiation and withdrawal of various medications, infections, pregnancy, and other conditions.^5,6 Although GPP most often occurs in adults, it also may arise in children and infants.³ In pregnancy, GPP is referred to as impetigo herpetiformis, despite having no etiologic ties with either herpes simplex virus or staphylococcal or streptococcal infection. Impetigo herpetiformis is considered one of the most dangerous dermatoses of pregnancy because of high rates of associated maternal and fetal morbidity.^6,7

Acute GPP has proven to be a challenging disease to treat due to the rarity and relapsing-remitting nature of the disease; additionally, there are relatively few randomized controlled trials investigating the efficacy and safety of treatments for GPP. This review summarizes the features of GPP, including the pathophysiology of the disease, clinical and histological manifestations, and recommendations for management based on a PubMed search of articles indexed for MEDLINE using MeSH terms pertaining to the disease, including generalized pustular psoriasis, impetigo herpetiformis, and von Zumbusch psoriasis.

Pathophysiology

The pathophysiology of GPP is only partially understood, but it is thought to have a distinct pattern of immune activation compared with plaque psoriasis.⁸ Although there is a considerable amount of overlap and cross-talk among cytokine pathways, GPP generally is driven by innate immunity and unrestrained IL-36 cytokine activity. In contrast, adaptive immune responses—namely the tumor necrosis factor (TNF) α, IL-23, IL-17, and IL-22 axes—underlie plaque psoriasis.^8-10

Proinflammatory IL-36 cytokines α, β, and γ, which are all part of the IL-1 superfamily, bind to the IL-36 receptor (IL-36R) to recruit and activate immune cells via various mediators, including IL-1β; IL-8; and chemokines CXCL1, CXCL2, and CXCL8.³ The IL-36 receptor antagonist (IL-36ra) acts to inhibit this inflammatory cascade.^3,8 Microarray analyses of skin biopsy samples have shown that overexpression of IL-17A, TNF-α, IL-1, and IL-36 are seen in both GPP and plaque psoriasis lesions, but GPP lesions had higher expression of IL-1β, IL-36α, and IL-36γ and elevated neutrophil chemokines—CXCL1, CXCL2, and CXCL8—compared with plaque psoriasis lesions.⁸

Gene Mutations Associated With GPP

There are 3 gene mutations that have been associated with pustular variants of psoriasis, though these mutations account for a minority of cases of GPP.⁴ Genetic screenings are not routinely indicated in patients with GPP, but they may be warranted in severe cases when a familial pattern of inheritance is suspected.⁴

IL36RN—The gene IL36RN codes the anti-inflammatory IL-36ra. Loss-of-function mutations in IL36RN lead to impairment of IL-36ra and consequently hyperactivity of the proinflammatory responses triggered by IL-36.³ Homozygous and heterozygous mutations in IL36RN have been observed in both familial and sporadic cases of GPP.^11-13 Subsequent retrospective analyses have identified the presence of IL36RN mutations in patients with GPP with frequencies ranging from 23% to 37%.^14-17IL36RN mutations are thought to be more common in patients without concomitant plaque psoriasis and have been associated with severe disease and early disease onset.¹⁵

CARD14—A gain-of-function mutation in CARD14 results in overactivation of the proinflammatory nuclear factor κB pathway and has been implicated in cases of GPP with concurrent psoriasis vulgaris. Interestingly, this may suggest distinct etiologies underlying GPP de novo and GPP in patients with a history of psoriasis.^18,19

AP1S3—A loss-of-function mutation in AP1S3 results in abnormal endosomal trafficking and autophagy as well as increased expression of IL-36α.^20,21

Clinical Presentation and DiagnosisCutaneous Manifestations of GPP

Generalized pustular psoriasis is characterized by the onset of widespread 2- to 3-mm sterile pustules on erythematous skin or within psoriasiform plaques⁴ (Figure). In patients with skin of color, the erythema may appear less obvious or perhaps slightly violaceous compared to White skin. Pustules may coalesce to form “lakes” of pus.⁵ Cutaneous symptoms include pain, burning, and pruritus. Associated mucosal findings may include cheilitis, geographic tongue, conjunctivitis, and uveitis.⁴

The severity of symptoms can vary greatly among patients as well as between flares within the same patient.^2,3 Four distinct patterns of GPP have been described. The von Zumbusch pattern is characterized by a rapid, generalized, painful, erythematous and pustular eruption accompanied by fever and asthenia. The pustules usually resolve after several days with extensive scaling. The annular pattern is characterized by annular, erythematous, scaly lesions with pustules present centrifugally. The lesions enlarge by centrifugal expansion over a period of hours to days, while healing occurs centrally. The exanthematic type is an acute eruption of small pustules that abruptly appear and disappear within a few days, usually from infection or medication initiation. Sometimes pustules appear within or at the edge of existing psoriatic plaques in a localized pattern—the fourth pattern—often following the exposure to irritants (eg, tars, anthralin).⁵

Impetigo Herpetiformis—Impetigo herpetiformis is a form of GPP associated with pregnancy. It generally presents early in the third trimester with symmetric erythematous plaques in flexural and intertriginous areas with pustules present at lesion margins. Lesions expand centrifugally, with pustulation present at the advancing edge.^6,7 Patients often are acutely ill with fever, delirium, vomiting, and tetany. Mucous membranes, including the tongue, mouth, and esophagus, also may be involved. The eruption typically resolves after delivery, though it often recurs with subsequent pregnancies, with the morbidity risk rising with each successive pregnancy.⁷

Systemic and Extracutaneous Manifestations of GPP

Although the severity of GPP is highly variable, skin manifestations often are accompanied by systemic manifestations of inflammation, including fever and malaise. Common laboratory abnormalities include leukocytosis with peripheral neutrophilia, a high serum C-reactive protein level, hypocalcemia, and hypoalbuminemia.²² Abnormal liver enzymes often are present and result from neutrophilic cholangitis, with alternating strictures and dilations of biliary ducts observed on magnetic resonance imaging.²³ Additional laboratory abnormalities are provided in Table 2. Other extracutaneous findings associated with GPP include arthralgia, edema, and characteristic psoriatic nail changes.⁴ Fatal complications include acute respiratory distress syndrome, renal dysfunction, cardiovascular shock, and sepsis.^24,25

Histologic Features

Given the potential for the skin manifestations of GPP to mimic other disorders, a skin biopsy is warranted to confirm the diagnosis. Generalized pustular psoriasis is histologically characterized by the presence of subcorneal macropustules (ie, spongiform pustules of Kogoj) formed by neutrophil infiltration into the spongelike network of the epidermis.⁶ Otherwise, the architecture of the epithelium in GPP is similar to that seen with plaque psoriasis, with parakeratosis, acanthosis, rete-ridge elongation, diminished stratum granulosum, and thinning of the suprapapillary epidermis, though the inflammatory cell infiltrate and edema are markedly more severe in GPP than plaque psoriasis.^3,4

Differential Diagnosis

There are many other cutaneous pustular diagnoses that must be ruled out when evaluating a patient with GPP (Table 1).²⁶ Acute generalized exanthematous pustulosis (AGEP) is a common mimicker of GPP that is differentiated histologically by the presence of eosinophils and necrotic keratinocytes.⁴ In addition to its distinct histopathologic findings, AGEP is classically associated with recent initiation of certain medications, most commonly penicillins, macrolides, quinolones, sulfonamides, terbinafine, and diltiazem.²⁷ In contrast, GPP more commonly is related to withdrawal of corticosteroids as well as initiation of some biologic medications, including anti-TNF agents.³ Generalized pustular psoriasis should be suspected over AGEP in patients with a personal or family history of psoriasis, though GPP may arise in patients with or without a history of psoriasis. Acute generalized exanthematous pustulosis usually is more abrupt in both onset and resolution compared with GPP, with clearance of pustules within a few days to weeks following cessation of the triggering factor.⁴

Other pustular variants of psoriasis (eg, palmoplantar pustular psoriasis, acrodermatitis continua of Hallopeau) are differentiated from GPP by their chronicity and localization to palmoplantar and/or ungual surfaces.⁵ Other differential diagnoses are listed in Table 1.

Diagnostic Criteria for GPP

Diagnostic criteria have been proposed for GPP (Table 2), including (1) the presence of sterile pustules, (2) systemic signs of inflammation, (3) laboratory abnormalities, (4) histopathologic confirmation of spongiform pustules of Kogoj, and (5) recurrence of symptoms.²² To definitively diagnose GPP, all 5 criteria must be met. To rule out mimickers, it may be worthwhile to perform Gram staining, potassium hydroxide preparation, in vitro cultures, and/or immunofluorescence testing.⁶

Treatment

Given the high potential for mortality associated with GPP, the most essential component of management is to ensure adequate supportive care. Any temperature, fluid, or electrolyte imbalances should be corrected as they arise. Secondary infections also must be identified and treated, if present, to reduce the risk for fatal complications, including systemic infection and sepsis. Precautions must be taken to ensure that serious end-organ damage, including hepatic, renal, and respiratory dysfunction, is avoided.

Adjunctive topical intervention often is initiated with bland emollients, corticosteroids, calcineurin inhibitors, and/or vitamin D derivatives to help soothe skin symptoms, but treatment with systemic therapies usually is warranted to achieve symptom control.^2,25 Importantly, there are no systemic or topical agents that have specifically been approved for the treatment of GPP in Europe or the United States.³ Given the absence of universally accepted treatment guidelines, therapeutic agents for GPP usually are selected based on clinical experience while also taking the extent of involvement and disease severity into consideration.³

Treatment Recommendations for Adults

Oral Systemic Agents—Treatment guidelines set forth by the National Psoriasis Foundation (NPF) in 2012 proposed that first-line therapies for GPP should be acitretin, cyclosporine, methotrexate, and infliximab.²⁸ However, since those guidelines were established, many new biologic therapies have been approved for the treatment of psoriasis and often are considered in the treatment of psoriasis subtypes, including GPP.²⁹ Although retinoids previously were considered to be a preferred first-line therapy, they are associated with a high incidence of adverse effects and must be used with caution in women of childbearing age.⁶ Oral acitretin at a dosage of 0.75 to 1.0 mg/kg/d has been shown to result in clinical improvement within 1 to 2 weeks, and a maintenance dosage of 0.125 to 0.25 mg/kg/d is required for several months to prevent recurrence.³⁰ Methotrexate—5.0 to 15.0 mg/wk, or perhaps higher in patients with refractory disease, increased by 2.5-mg intervals until symptoms improve—is recommended by the NPF in patients who are unresponsive or cannot tolerate retinoids, though close monitoring for hematologic abnormalities is required. Cyclosporine 2.5 to 5.0 mg/kg/d is considered an alternative to methotrexate and retinoids; it has a faster onset of action, with improvement reported as early as 2 weeks after initiation of therapy.^1,28 Although cyclosporine may be effective in the acute phase, especially in severe cases of GPP, long-term use of cyclosporine is not recommended because of the potential for renal dysfunction and hypertension.³¹

Biologic Agents—More recent evidence has accumulated supporting the efficacy of anti-TNF agents in the treatment of GPP, suggesting the positioning of these agents as first line. A number of case series have shown dramatic and rapid improvement of GPP with intravenous infliximab 3 to 5 mg/kg, with results observed hours to days after the first infusion.^32-37 Thus, infliximab is recommended as first-line treatment in severe acute cases, though its efficacy as a maintenance therapy has not been sufficiently investigated.⁶ Case reports and case series document the safety and efficacy of adalimumab 40 to 80 mg every 1 to 2 weeks^38,39 and etanercept 25 to 50 mg twice weekly^40-42 in patients with recalcitrantGPP. Therefore, these anti-TNF agents may be considered in patients who are nonresponsive to treatment with infliximab.

Rarely, there have been reports of paradoxical induction of GPP with the use of some anti-TNF agents,^43-45 which may be due to a cytokine imbalance characterized by unopposed IFN-α activation.⁶ In patients with a history of GPP after initiation of a biologic, treatment with agents from within the offending class should be avoided.

The IL-17A monoclonal antibodies secukinumab, ixekizumab, and brodalumab have been shown in open-label phase 3 studies to result in disease remission at 12 weeks.^46-48 Treatment with guselkumab, an IL-23 monoclonal antibody, also has demonstrated efficacy in patients with GPP.⁴⁹ Ustekinumab, an IL-12/23 inhibitor, in combination with acitretin also has been shown to be successful in achieving disease remission after a few weeks of treatment.⁵⁰

More recent case reports have shown the efficacy of IL-1 inhibitors including gevokizumab, canakinumab, and anakinra in achieving GPP clearance, though more prospective studies are needed to evaluate their efficacy.^51-53 Given the etiologic association between IL-1 disinhibition and GPP, future investigations of these therapies as well as those that target the IL-36 pathway may prove to be particularly interesting.

Phototherapy and Combination Therapies—Phototherapy may be considered as maintenance therapy after disease control is achieved, though it is not considered appropriate for acute cases.²⁸ Combination therapies with a biologic plus a nonbiologic systemic agent or alternating among various biologics may allow physicians to maximize benefits and minimize adverse effects in the long term, though there is insufficient evidence to suggest any specific combination treatment algorithm for GPP.²⁸

Treatment Recommendations for Pediatric Patients

Based on a small number of case series and case reports, the first-line treatment strategy for children with GPP is similar to adults. Given the notable adverse events of most oral systemic agents, biologic therapies may emerge as first-line therapy in the pediatric population as more evidence accumulates.²⁸

Treatment Recommendations for Pregnant Patients

Systemic corticosteroids are widely considered to be the first-line treatments for the management of impetigo herpetiformis.⁷ Low-dose prednisone (15–30 mg/d) usually is effective, but severe cases may require increasing the dosage to 60 mg/d.⁶ Given the potential for rebound flares upon withdrawal of systemic corticosteroids, these agents must be gradually tapered after the resolution of symptoms.

Certolizumab pegol also is an attractive option in pregnant patients with impetigo herpetiformis because of its favorable safety profile and negligible mother-to-infant transfer through the placenta or breast milk. It has been shown to be effective in treating GPP and impetigo herpetiformis during pregnancy in recently published case reports.^54,55 In refractory cases, other TNF-α inhibitors (eg, adalimumab, infliximab, etanercept) or cyclosporine may be considered. However, cautious medical monitoring is warranted, as little is known about the potential adverse effects of these agents to the mother and fetus.^28,56 Data from transplant recipients along with several case reports indicate that cyclosporine is not associated with an increased risk for adverse effects during pregnancy at a dose of 2 to 3 mg/kg.^57-59 Both methotrexate and retinoids are known teratogens and are therefore contraindicated in pregnant patients.⁵⁶

If pustules do not resolve in the postpartum period, patients should be treated with standard GPP therapies. However, long-term and population studies are lacking regarding the potential for infant exposure to systemic agents in breast milk. Therefore, the NPF recommends avoiding breastfeeding while taking systemic medications, if possible.⁵⁶

Limitations of Treatment Recommendations

The ability to generate an evidence-based treatment strategy for GPP is limited by a lack of high-quality studies investigating the efficacy and safety of treatments in patients with GPP due to the rarity and relapsing-remitting nature of the disease, which makes randomized controlled trials difficult to conduct. The quality of the available research is further limited by the lack of validated outcome measures to specifically assess improvements in patients with GPP, such that results are difficult to synthesize and compare among studies.³¹

Conclusion

Although limited, the available research suggests that treatment with various biologics, especially infliximab, is effective in achieving rapid clearance in patients with GPP. In general, biologics may be the most appropriate treatment option in patients with GPP given their relatively favorable safety profiles. Other oral systemic agents, including acitretin, cyclosporine, and methotrexate, have limited evidence to support their use in the acute phase, but their safety profiles often limit their utility in the long-term. Emerging evidence regarding the association of GPP with IL36RN mutations suggests a unique role for agents targeting the IL-36 or IL-1 pathways, though this has yet to be thoroughly investigated.

To the Editor:

Psoriasis affects 2% to 3% of the US population and is one of the more commonly diagnosed dermatologic conditions.^1-3 Experts agree that common cutaneous diseases such as psoriasis present differently in patients with skin of color (SOC) compared to non-SOC patients.^3,4 Despite the prevalence of psoriasis, data on these morphologic differences are limited.^3-5 We performed a retrospective chart review comparing characteristics of psoriasis in SOC and non-SOC patients.

Through a search of electronic health records, we identified patients with an International Classification of Diseases, 10th Revision, diagnosis of psoriasis who were 18 years or older and were evaluated in the dermatology department between August 2015 and June 2020 at University Medical Center, an academic institution in New Orleans, Louisiana. Photographs and descriptions of lesions from these patients were reviewed. Patient data collected included age, sex, psoriasis classification, insurance status, self-identified race and ethnicity, location of lesion(s), biopsy, final diagnosis, and average number of visits or days required for accurate diagnosis. Self-identified SOC race and ethnicity categories included Black or African American, Hispanic, Asian, American Indian and Alaskan Native, Native Hawaiian and Other Pacific Islander, and “other.”

All analyses were conducted using R-4.0.1 statistics software. Categorical variables were compared in SOC and non-SOC groups using Fisher exact tests. Continuous covariates were conducted using a Wilcoxon rank sum test.

In total, we reviewed 557 charts. Four patients who declined to identify their race or ethnicity were excluded, yielding 286 SOC and 267 non-SOC patients (N=553). A total of 276 patients (131 SOC; 145 non-SOC) with a prior diagnosis of psoriasis were excluded in the days to diagnosis analysis. Twenty patients (15, SOC; 5, non-SOC) were given a diagnosis of a disease other than psoriasis when evaluated in the dermatology department.

Distributions between racial groups differed for insurance status, sex, psoriasis classification, biopsy status, and days between first dermatology visit and diagnosis. Skin of color patients had significantly longer days between initial presentation to dermatology and final diagnosis vs non-SOC patients (180.11 and 60.27 days, respectively; P=.001). Skin of color patients had a higher rate of palmoplantar psoriasis and severe plaque psoriasis (ie, >10% body surface area involvement) at presentation.

Several multivariable regression analyses were performed. Skin of color patients had significantly higher odds of biopsy compared to non-SOC patients (adjusted odds ratio [95% CI]=4 [2.05-7.82]; P<.001)(Figure 1). There were no significant predictors for severe plaque psoriasis involving more than 10% body surface area. Skin of color patients had a significantly longer time to diagnosis than non-SOC patients (P=.006)(Figure 2). On average, patients with SOC waited 3.23 times longer for a diagnosis than their non-SOC counterparts (95% CI, 1.42-7.36).

Our data reveal striking racial disparities in psoriasis care. Worse outcomes for patients with SOC compared to non-SOC patients may result from physicians’ inadequate familiarity with diverse presentations of psoriasis, including more frequent involvement of special body sites in SOC. Other likely contributing factors that we did not evaluate include socioeconomic barriers to health care, lack of physician diversity, missed appointments, and a paucity of literature on the topic of differentiating morphologies of psoriasis in SOC and non-SOC patients. Our study did not examine the effects of sex, tobacco use, or prior or current therapy, and it excluded pediatric patients.

To improve dermatologic outcomes for our increasingly diverse patient population, more studies must be undertaken to elucidate and document disparities in care for SOC populations.

To the Editor:

Psoriasis affects 2% to 3% of the US population and is one of the more commonly diagnosed dermatologic conditions.^1-3 Experts agree that common cutaneous diseases such as psoriasis present differently in patients with skin of color (SOC) compared to non-SOC patients.^3,4 Despite the prevalence of psoriasis, data on these morphologic differences are limited.^3-5 We performed a retrospective chart review comparing characteristics of psoriasis in SOC and non-SOC patients.

Through a search of electronic health records, we identified patients with an International Classification of Diseases, 10th Revision, diagnosis of psoriasis who were 18 years or older and were evaluated in the dermatology department between August 2015 and June 2020 at University Medical Center, an academic institution in New Orleans, Louisiana. Photographs and descriptions of lesions from these patients were reviewed. Patient data collected included age, sex, psoriasis classification, insurance status, self-identified race and ethnicity, location of lesion(s), biopsy, final diagnosis, and average number of visits or days required for accurate diagnosis. Self-identified SOC race and ethnicity categories included Black or African American, Hispanic, Asian, American Indian and Alaskan Native, Native Hawaiian and Other Pacific Islander, and “other.”

All analyses were conducted using R-4.0.1 statistics software. Categorical variables were compared in SOC and non-SOC groups using Fisher exact tests. Continuous covariates were conducted using a Wilcoxon rank sum test.

In total, we reviewed 557 charts. Four patients who declined to identify their race or ethnicity were excluded, yielding 286 SOC and 267 non-SOC patients (N=553). A total of 276 patients (131 SOC; 145 non-SOC) with a prior diagnosis of psoriasis were excluded in the days to diagnosis analysis. Twenty patients (15, SOC; 5, non-SOC) were given a diagnosis of a disease other than psoriasis when evaluated in the dermatology department.

Distributions between racial groups differed for insurance status, sex, psoriasis classification, biopsy status, and days between first dermatology visit and diagnosis. Skin of color patients had significantly longer days between initial presentation to dermatology and final diagnosis vs non-SOC patients (180.11 and 60.27 days, respectively; P=.001). Skin of color patients had a higher rate of palmoplantar psoriasis and severe plaque psoriasis (ie, >10% body surface area involvement) at presentation.

Several multivariable regression analyses were performed. Skin of color patients had significantly higher odds of biopsy compared to non-SOC patients (adjusted odds ratio [95% CI]=4 [2.05-7.82]; P<.001)(Figure 1). There were no significant predictors for severe plaque psoriasis involving more than 10% body surface area. Skin of color patients had a significantly longer time to diagnosis than non-SOC patients (P=.006)(Figure 2). On average, patients with SOC waited 3.23 times longer for a diagnosis than their non-SOC counterparts (95% CI, 1.42-7.36).

Our data reveal striking racial disparities in psoriasis care. Worse outcomes for patients with SOC compared to non-SOC patients may result from physicians’ inadequate familiarity with diverse presentations of psoriasis, including more frequent involvement of special body sites in SOC. Other likely contributing factors that we did not evaluate include socioeconomic barriers to health care, lack of physician diversity, missed appointments, and a paucity of literature on the topic of differentiating morphologies of psoriasis in SOC and non-SOC patients. Our study did not examine the effects of sex, tobacco use, or prior or current therapy, and it excluded pediatric patients.

To improve dermatologic outcomes for our increasingly diverse patient population, more studies must be undertaken to elucidate and document disparities in care for SOC populations.

To the Editor:

Psoriasis affects 2% to 3% of the US population and is one of the more commonly diagnosed dermatologic conditions.^1-3 Experts agree that common cutaneous diseases such as psoriasis present differently in patients with skin of color (SOC) compared to non-SOC patients.^3,4 Despite the prevalence of psoriasis, data on these morphologic differences are limited.^3-5 We performed a retrospective chart review comparing characteristics of psoriasis in SOC and non-SOC patients.

Through a search of electronic health records, we identified patients with an International Classification of Diseases, 10th Revision, diagnosis of psoriasis who were 18 years or older and were evaluated in the dermatology department between August 2015 and June 2020 at University Medical Center, an academic institution in New Orleans, Louisiana. Photographs and descriptions of lesions from these patients were reviewed. Patient data collected included age, sex, psoriasis classification, insurance status, self-identified race and ethnicity, location of lesion(s), biopsy, final diagnosis, and average number of visits or days required for accurate diagnosis. Self-identified SOC race and ethnicity categories included Black or African American, Hispanic, Asian, American Indian and Alaskan Native, Native Hawaiian and Other Pacific Islander, and “other.”

All analyses were conducted using R-4.0.1 statistics software. Categorical variables were compared in SOC and non-SOC groups using Fisher exact tests. Continuous covariates were conducted using a Wilcoxon rank sum test.

In total, we reviewed 557 charts. Four patients who declined to identify their race or ethnicity were excluded, yielding 286 SOC and 267 non-SOC patients (N=553). A total of 276 patients (131 SOC; 145 non-SOC) with a prior diagnosis of psoriasis were excluded in the days to diagnosis analysis. Twenty patients (15, SOC; 5, non-SOC) were given a diagnosis of a disease other than psoriasis when evaluated in the dermatology department.

Distributions between racial groups differed for insurance status, sex, psoriasis classification, biopsy status, and days between first dermatology visit and diagnosis. Skin of color patients had significantly longer days between initial presentation to dermatology and final diagnosis vs non-SOC patients (180.11 and 60.27 days, respectively; P=.001). Skin of color patients had a higher rate of palmoplantar psoriasis and severe plaque psoriasis (ie, >10% body surface area involvement) at presentation.

Several multivariable regression analyses were performed. Skin of color patients had significantly higher odds of biopsy compared to non-SOC patients (adjusted odds ratio [95% CI]=4 [2.05-7.82]; P<.001)(Figure 1). There were no significant predictors for severe plaque psoriasis involving more than 10% body surface area. Skin of color patients had a significantly longer time to diagnosis than non-SOC patients (P=.006)(Figure 2). On average, patients with SOC waited 3.23 times longer for a diagnosis than their non-SOC counterparts (95% CI, 1.42-7.36).

Our data reveal striking racial disparities in psoriasis care. Worse outcomes for patients with SOC compared to non-SOC patients may result from physicians’ inadequate familiarity with diverse presentations of psoriasis, including more frequent involvement of special body sites in SOC. Other likely contributing factors that we did not evaluate include socioeconomic barriers to health care, lack of physician diversity, missed appointments, and a paucity of literature on the topic of differentiating morphologies of psoriasis in SOC and non-SOC patients. Our study did not examine the effects of sex, tobacco use, or prior or current therapy, and it excluded pediatric patients.

To improve dermatologic outcomes for our increasingly diverse patient population, more studies must be undertaken to elucidate and document disparities in care for SOC populations.

Psoriasis is a chronic inflammatory skin disease characterized by erythematous scaly plaques that can invoke substantial pain, pruritus, and quality-of-life disturbance in patients. Topical therapies are the most commonly used medications for treating psoriasis, with one study (N = 128,308) showing that more than 85% of patients with psoriasis were managed solely with topical medications. ¹ For patients with mild to moderate psoriasis, topical agents alone may be able to control disease completely. For those with more severe disease, topical agents are used adjunctively with systemic or biologic agents to optimize disease control in localized areas.

The American Academy of Dermatology (AAD) and National Psoriasis Foundation (NPF) published guidelines in 2020 for managing psoriasis with topical agents in adults.² This review presents the most up-to-date clinical recommendations for topical agent use in adult patients with psoriasis and elaborates on each drug’s pharmacologic and safety profile. Specifically, evidence-based treatment recommendations for topical steroids, calcineurin inhibitors (CNIs), vitamin D analogues, retinoids (tazarotene), emollients, keratolytics (salicylic acid), anthracenes (anthralin), and keratoplastics (coal tar) will be addressed (Table 1). Recommendations for combination therapy with other treatment modalities including UVB light therapy, biologics, and systemic nonbiologic agents also will be discussed.

Selecting a Topical Agent Based on Disease Localization

When treating patients with psoriasis with topical therapies, clinicians should take into consideration drug potency, as it determines how effective a treatment will be in penetrating the skin barrier. Plaque characteristics, such as distribution (localized vs widespread), anatomical localization (flexural, scalp, palms/soles/nails), size (large vs small), and thickness (thick vs thin), not only influence treatment effectiveness but also the incidence of drug-related adverse events. Furthermore, preferred topical therapies are tailored to each patient based on disease characteristics and activity. Coal tar and anthralin have been used less frequently than other topical therapies for psoriasis because of their undesirable side-effect profiles (Table 1).³

Face and Intertriginous Regions—The face and intertriginous areas are sensitive because skin tends to be thin in these regions. Emollients are recommended for disease in these locations given their safety and flexibility in use for most areas. Conversely, anthralin should be avoided on the face, intertriginous areas, and even highly visible locations because of the potential for skin staining. Low-potency corticosteroids also have utility in psoriasis distributed on the face and intertriginous regions. Additionally, application of steroids around the eyes should be cautioned because topical steroids can induce ocular complications such as glaucoma and cataracts in rare circumstances.⁴

Off-label use of CNIs for psoriasis on the face and intertriginous areas also is effective. Currently, there is a level B recommendation for off-label use of 0.1% tacrolimus for up to 8 weeks for inverse psoriasis or psoriasis on the face. Off-label use of pimecrolimus for 4 to 8 weeks also can be considered for inverse psoriasis. Combination therapy consisting of hydrocortisone with calcipotriol ointment is another effective regimen.⁵ One study also suggested that use of crisaborole for 4 to 8 weeks in intertriginous psoriasis can be effective and well tolerated.⁶

Scalp—The vehicle of medication administration is especially important in hair-bearing areas such as the scalp, as these areas are challenging for medication application and patient adherence. Thus, patient preferences for the vehicle must be considered. Several studies have been conducted to assess preference for various vehicles in scalp psoriasis. A foam or solution may be preferable to ointments, gels, or creams.⁷ Gels may be preferred over ointments.⁸ There is a level A recommendation supporting the use of class 1 to 7 topical steroids for a minimum of 4 weeks as initial and maintenance treatment of scalp psoriasis. The highest level of evidence (level A) also supports the use of calcipotriol foam or combination therapy of calcipotriol–betamethasone dipropionate gel for 4 to 12 weeks as treatment of mild to moderate scalp psoriasis.

Nails—Several options for topical medications have been recommended for the treatment of nail psoriasis. Currently, there is a level B recommendation for the use of tazarotene for the treatment of nail psoriasis. Another effective regimen is combination therapy with vitamin D analogues and betamethasone dipropionate.⁹ Topical steroid use for nail psoriasis should be limited to 12 weeks because of the risk for bone atrophy with chronic steroid use.

Palmoplantar—The palms and soles have a thicker epidermal layer than other areas of the body. As a result, class 1 corticosteroids can be used for palmoplantar psoriasis for more than 4 weeks with vigilant monitoring for adverse effects such as skin atrophy, tachyphylaxis, or tinea infection. Tazarotene also has been shown to be helpful in treating palmoplantar psoriasis.

Resistant Disease—Intralesional steroids are beneficial treatment options for recalcitrant psoriasis in glabrous areas, as well as for palmoplantar, nail, and scalp psoriasis. Up to 10 mg/mL of triamcinolone acetonide used every 3 to 4 weeks is an effective regimen.¹⁰Pregnancy/Breastfeeding—Women of childbearing potential have additional safety precautions that should be considered during medication selection. Emollients have been shown to be safe during pregnancy and lactation. Currently, there is little known about CNI use during pregnancy. During lactation, CNIs can be used by breastfeeding mothers in most areas, excluding the breasts. Evaluation of the safety of anthralin and vitamin D analogues during pregnancy and lactation have not been studied. For these agents, dermatologists need to use their clinical judgment to weigh the risks and benefits of medication, particularly in patients requiring occlusion, higher medication doses, or treatment over a large surface area. Salicylic acid should be used with caution in pregnant and breastfeeding mothers because it is a pregnancy category C drug. Lower-potency corticosteroids may be used with caution during pregnancy and breastfeeding. More potent corticosteroids and coal tar, however, should be avoided. Similarly, tazarotene use is contraindicated in pregnancy. According to the US Food and Drug Administration labels for all forms of topical tazarotene, a pregnancy test must be obtained 2 weeks prior to tazarotene treatment initiation in women of childbearing potential because of the risk for serious fetal malformations and toxicity.

Recommendations, Risks, and Benefits of Topical Therapy for the Management of Psoriasis

Topical Corticosteroids—Topical corticosteroids (TCs) are widely used for inflammatory skin conditions and are available in a variety of strengths (Table 2). They are thought to exert their action by regulating the gene transcription of proinflammatory mediators. For psoriasis, steroids are recommended for 2 to 4 weeks, depending on disease severity. Although potent and superpotent steroids are more effective than mild- to moderate-strength TCs, use of lower-potency TCs may be warranted depending on disease distribution and localization.¹¹ For treatment of psoriasis with no involvement of the intertriginous areas, use of class 1 to 5 TCs for up to 4 weeks is recommended.

For moderate to severe psoriasis with 20% or less body surface area (BSA) affected, combination therapy consisting of mometasone and salicylic acid has been shown to be more effective than mometasone alone.^12,13 There currently is a level A recommendation for the use of combination therapy with class 1 TCs and etanercept for 12 weeks in patients with moderate to severe psoriasis who require both systemic and topical therapies for disease control. Similarly, combination therapy with infliximab and high-potency TCs has a level B recommendation to enhance efficacy for the treatment of moderate to severe psoriasis.¹⁴ High-quality studies on the use of TCs with anti–IL-12/IL-23, anti–IL-23, and anti–IL-17 currently are unavailable, but the combination is not expected to be unsafe.^14,15 Combination therapy of betamethasone dipropionate ointment and low-dose cyclosporine is an alternative regimen with a level B recommendation.

The most common adverse effects with use of TCs are skin thinning and atrophy, telangiectasia, and striae (Table 1). With clinical improvement of disease, it is recommended that clinicians taper TCs to prevent rebound effect. To decrease TC-related adverse effects, clinicians should use combination therapy with steroid-sparing agents for disease maintenance, transition to lower-potency corticosteroids, or use intermittent steroid therapy. Systemic effects of TC use include hypothalamic-pituitary-adrenal axis suppression, Cushing syndrome, and osteonecrosis of the femoral head.^16-18 These systemic effects with TC use are rare unless treatment is for disease involving greater than 20% BSA or occlusion for more than 4 weeks.

Calcineurin Inhibitors—Calcineurin inhibitors inhibit calcineurin phosphorylation and T-cell activation, subsequently decreasing the expression of proinflammatory cytokines. Currently, they are not approved by the US Food and Drug Administration to treat psoriasis but have demonstrated efficacy in randomized control trials (RCTs) for facial and intertriginous psoriasis. In RCTs, 71% of patients using pimecrolimus cream 0.1% twice daily for 8 weeks achieved an investigator global assessment score of clear (0) or almost clear (1) compared with 21% of placebo-treated patients (N=57).¹⁹ Other trials have shown that 65% of patients receiving tacrolimus ointment 0.1% for 8 weeks achieved an investigator global assessment score of 0 or 1 compared with 31% of placebo-treated patients (N=167).²⁰ Because of their efficacy in RCTs, CNIs commonly are used off label to treat psoriasis.

The most common adverse effects with CNI use are burning, pruritus, and flushing with alcohol ingestion (Table 1). Additionally, CNIs have a black box warning that use may increase the risk for malignancy, but this risk has not been demonstrated with topical use in humans.²¹Vitamin D Analogues—The class of vitamin D analogues—calcipotriol/calcipotriene and calcitriol—frequently are used to treat psoriasis. Vitamin D analogues exert their beneficial effects by inhibiting keratinocyte proliferation and enhancing keratinocyte differentiation. They also are ideal for long-term use (up to 52 weeks) in mild to moderate psoriasis and can be used in combination with class 2 and 3 TCs. There is a level A recommendation that supports the use of combination therapy with calcipotriol and TCs for the treatment of mild to moderate psoriasis.

For severe psoriasis, many studies have investigated the efficacy of combination therapy with vitamin D analogues and systemic treatments. Combination therapy with calcipotriol and methotrexate or calcipotriol and acitretin are effective treatment regimens with level A recommendations. Calcipotriol–betamethasone dipropionate ointment in combination with low-dose cyclosporine is an alternative option with a level B recommendation. Because vitamin D analogues are inactivated by UVA and UVB radiation, clinicians should advise their patients to use vitamin D analogues after receiving UVB phototherapy.²²

Common adverse effects of vitamin D analogues include burning, pruritus, erythema, and dryness (Table 1). Hypercalcemia and parathyroid hormone suppression are extremely rare unless treatment occurs over a large surface area (>30% BSA) or the patient has concurrent renal disease or impairments in calcium metabolism.

Tazarotene—Tazarotene is a topical retinoid that acts by decreasing keratinocyte proliferation, facilitating keratinocyte differentiation, and inhibiting inflammation. Patients with mild to moderate psoriasis are recommended to receive tazarotene treatment for 8 to 12 weeks. In several RCTs, tazarotene gel 0.1% and tazarotene cream 0.1% and 0.05% achieved treatment success in treating plaque psoriasis.^23,24

For increased efficacy, clinicians can recommend combination therapy with tazarotene and a TC. Combination therapy with tazarotene and a mid- or high-potency TC for 8 to 16 weeks has been shown to be more effective than treatment with tazarotene alone.²⁵ Thus, there is a level A recommendation for use of this combination to treat mild to moderate psoriasis. Agents used in combination therapy work synergistically to decrease the length of treatment and increase the duration of remission. The frequency of adverse effects, such as irritation from tazarotene and skin atrophy from TCs, also are reduced.²⁶ Combination therapy with tazarotene and narrowband UVB (NB-UVB) is another effective option that requires less UV radiation than NB-UVB alone because of the synergistic effects of both treatment modalities.²⁷ Clinicians should counsel patients on the adverse effects of tazarotene, which include local irritation, burning, pruritus, and erythema (Table 1).

Emollients—Emollients are nonmedicated moisturizers that decrease the amount of transepidermal water loss. There is a level B recommendation for use of emollients and TCs in combination for 4 to 8 weeks to treat psoriasis. In fact, combination therapy with mometasone and emollients has demonstrated greater improvement in symptoms of palmoplantar psoriasis (ie, erythema, desquamation, infiltration, BSA involvement) than mometasone alone.²⁸ Emollients are safe options that can be used on all areas of the body and during pregnancy and lactation. Although adverse effects of emollients are rare, clinicians should counsel patients on the risk for contact dermatitis if specific allergies to ingredients/fragrances exist (Table 1).

Salicylic Acid—Salicylic acid is a topical keratolytic that can be used to treat psoriatic plaques. Use of salicylic acid for 8 to 16 weeks has been shown to be effective for mild to moderate psoriasis. Combination therapy of salicylic acid and TCs in patients with 20% or less BSA affected is a safe and effective option with a level B recommendation. Combination therapy with salicylic acid and calcipotriene, however, should be avoided because calcipotriene is inactivated by salicylic acid. It also is recommended that salicylic acid application follow phototherapy when both treatment modalities are used in combination.^29,30 Clinicians should be cautious about using salicylic acid in patients with renal or hepatic disease because of the increased risk for salicylate toxicity (Table 1).

Anthralin—Anthralin is a synthetic hydrocarbon derivative that has been shown to reduce inflammation and normalize keratinocyte proliferation through an unknown mechanism. It is recommended that patients with mild to moderate psoriasis receive anthralin treatment for 8 to 12 weeks, with a maximum application time of 2 hours per day. Combination therapy of excimer laser and anthralin has been shown to be more effective in treating psoriasis than anthralin alone.³¹ Therefore, clinicians have the option of including excimer laser therapy for additional disease control. Anthralin should be avoided on the face, flexural regions, and highly visible areas because of potential skin staining (Table 1). Other adverse effects include application-site burning and erythema.

Coal Tar—Coal tar is a heterogenous mixture of aromatic hydrocarbons that is an effective treatment of psoriasis because of its inherent anti-inflammatory and keratoplastic properties. There is high-quality evidence supporting a level A recommendation for coal tar use in mild to moderate psoriasis. Combination therapy with NB-UVB and coal tar (also known as Goeckerman therapy) is a recommended treatment option with a quicker onset of action and improved outcomes compared with NB-UVB therapy alone.^32,33 Adverse events of coal tar include application-site irritation, folliculitis, contact dermatitis, phototoxicity, and skin pigmentation (Table 1).

Conclusion

Topical medications are versatile treatment options that can be utilized as monotherapy or adjunct therapy for mild to severe psoriasis. Benefits of topical agents include minimal required monitoring, few contraindications, and direct localized effect on plaques. Therefore, side effects with topical agent use rarely are systemic. Medication interactions are less of a concern with topical therapies; thus, they have better safety profiles compared with systemic therapies. This clinical review summarizes the recently published evidence-based guidelines from the AAD and NPF on the use of topical agents in psoriasis and may be a useful guiding framework for clinicians in their everyday practice.

Psoriasis is a chronic inflammatory skin disease characterized by erythematous scaly plaques that can invoke substantial pain, pruritus, and quality-of-life disturbance in patients. Topical therapies are the most commonly used medications for treating psoriasis, with one study (N = 128,308) showing that more than 85% of patients with psoriasis were managed solely with topical medications. ¹ For patients with mild to moderate psoriasis, topical agents alone may be able to control disease completely. For those with more severe disease, topical agents are used adjunctively with systemic or biologic agents to optimize disease control in localized areas.

The American Academy of Dermatology (AAD) and National Psoriasis Foundation (NPF) published guidelines in 2020 for managing psoriasis with topical agents in adults.² This review presents the most up-to-date clinical recommendations for topical agent use in adult patients with psoriasis and elaborates on each drug’s pharmacologic and safety profile. Specifically, evidence-based treatment recommendations for topical steroids, calcineurin inhibitors (CNIs), vitamin D analogues, retinoids (tazarotene), emollients, keratolytics (salicylic acid), anthracenes (anthralin), and keratoplastics (coal tar) will be addressed (Table 1). Recommendations for combination therapy with other treatment modalities including UVB light therapy, biologics, and systemic nonbiologic agents also will be discussed.

Selecting a Topical Agent Based on Disease Localization

When treating patients with psoriasis with topical therapies, clinicians should take into consideration drug potency, as it determines how effective a treatment will be in penetrating the skin barrier. Plaque characteristics, such as distribution (localized vs widespread), anatomical localization (flexural, scalp, palms/soles/nails), size (large vs small), and thickness (thick vs thin), not only influence treatment effectiveness but also the incidence of drug-related adverse events. Furthermore, preferred topical therapies are tailored to each patient based on disease characteristics and activity. Coal tar and anthralin have been used less frequently than other topical therapies for psoriasis because of their undesirable side-effect profiles (Table 1).³

Face and Intertriginous Regions—The face and intertriginous areas are sensitive because skin tends to be thin in these regions. Emollients are recommended for disease in these locations given their safety and flexibility in use for most areas. Conversely, anthralin should be avoided on the face, intertriginous areas, and even highly visible locations because of the potential for skin staining. Low-potency corticosteroids also have utility in psoriasis distributed on the face and intertriginous regions. Additionally, application of steroids around the eyes should be cautioned because topical steroids can induce ocular complications such as glaucoma and cataracts in rare circumstances.⁴

Off-label use of CNIs for psoriasis on the face and intertriginous areas also is effective. Currently, there is a level B recommendation for off-label use of 0.1% tacrolimus for up to 8 weeks for inverse psoriasis or psoriasis on the face. Off-label use of pimecrolimus for 4 to 8 weeks also can be considered for inverse psoriasis. Combination therapy consisting of hydrocortisone with calcipotriol ointment is another effective regimen.⁵ One study also suggested that use of crisaborole for 4 to 8 weeks in intertriginous psoriasis can be effective and well tolerated.⁶

Scalp—The vehicle of medication administration is especially important in hair-bearing areas such as the scalp, as these areas are challenging for medication application and patient adherence. Thus, patient preferences for the vehicle must be considered. Several studies have been conducted to assess preference for various vehicles in scalp psoriasis. A foam or solution may be preferable to ointments, gels, or creams.⁷ Gels may be preferred over ointments.⁸ There is a level A recommendation supporting the use of class 1 to 7 topical steroids for a minimum of 4 weeks as initial and maintenance treatment of scalp psoriasis. The highest level of evidence (level A) also supports the use of calcipotriol foam or combination therapy of calcipotriol–betamethasone dipropionate gel for 4 to 12 weeks as treatment of mild to moderate scalp psoriasis.

Nails—Several options for topical medications have been recommended for the treatment of nail psoriasis. Currently, there is a level B recommendation for the use of tazarotene for the treatment of nail psoriasis. Another effective regimen is combination therapy with vitamin D analogues and betamethasone dipropionate.⁹ Topical steroid use for nail psoriasis should be limited to 12 weeks because of the risk for bone atrophy with chronic steroid use.

Palmoplantar—The palms and soles have a thicker epidermal layer than other areas of the body. As a result, class 1 corticosteroids can be used for palmoplantar psoriasis for more than 4 weeks with vigilant monitoring for adverse effects such as skin atrophy, tachyphylaxis, or tinea infection. Tazarotene also has been shown to be helpful in treating palmoplantar psoriasis.

Resistant Disease—Intralesional steroids are beneficial treatment options for recalcitrant psoriasis in glabrous areas, as well as for palmoplantar, nail, and scalp psoriasis. Up to 10 mg/mL of triamcinolone acetonide used every 3 to 4 weeks is an effective regimen.¹⁰Pregnancy/Breastfeeding—Women of childbearing potential have additional safety precautions that should be considered during medication selection. Emollients have been shown to be safe during pregnancy and lactation. Currently, there is little known about CNI use during pregnancy. During lactation, CNIs can be used by breastfeeding mothers in most areas, excluding the breasts. Evaluation of the safety of anthralin and vitamin D analogues during pregnancy and lactation have not been studied. For these agents, dermatologists need to use their clinical judgment to weigh the risks and benefits of medication, particularly in patients requiring occlusion, higher medication doses, or treatment over a large surface area. Salicylic acid should be used with caution in pregnant and breastfeeding mothers because it is a pregnancy category C drug. Lower-potency corticosteroids may be used with caution during pregnancy and breastfeeding. More potent corticosteroids and coal tar, however, should be avoided. Similarly, tazarotene use is contraindicated in pregnancy. According to the US Food and Drug Administration labels for all forms of topical tazarotene, a pregnancy test must be obtained 2 weeks prior to tazarotene treatment initiation in women of childbearing potential because of the risk for serious fetal malformations and toxicity.

Recommendations, Risks, and Benefits of Topical Therapy for the Management of Psoriasis

Topical Corticosteroids—Topical corticosteroids (TCs) are widely used for inflammatory skin conditions and are available in a variety of strengths (Table 2). They are thought to exert their action by regulating the gene transcription of proinflammatory mediators. For psoriasis, steroids are recommended for 2 to 4 weeks, depending on disease severity. Although potent and superpotent steroids are more effective than mild- to moderate-strength TCs, use of lower-potency TCs may be warranted depending on disease distribution and localization.¹¹ For treatment of psoriasis with no involvement of the intertriginous areas, use of class 1 to 5 TCs for up to 4 weeks is recommended.

For moderate to severe psoriasis with 20% or less body surface area (BSA) affected, combination therapy consisting of mometasone and salicylic acid has been shown to be more effective than mometasone alone.^12,13 There currently is a level A recommendation for the use of combination therapy with class 1 TCs and etanercept for 12 weeks in patients with moderate to severe psoriasis who require both systemic and topical therapies for disease control. Similarly, combination therapy with infliximab and high-potency TCs has a level B recommendation to enhance efficacy for the treatment of moderate to severe psoriasis.¹⁴ High-quality studies on the use of TCs with anti–IL-12/IL-23, anti–IL-23, and anti–IL-17 currently are unavailable, but the combination is not expected to be unsafe.^14,15 Combination therapy of betamethasone dipropionate ointment and low-dose cyclosporine is an alternative regimen with a level B recommendation.

The most common adverse effects with use of TCs are skin thinning and atrophy, telangiectasia, and striae (Table 1). With clinical improvement of disease, it is recommended that clinicians taper TCs to prevent rebound effect. To decrease TC-related adverse effects, clinicians should use combination therapy with steroid-sparing agents for disease maintenance, transition to lower-potency corticosteroids, or use intermittent steroid therapy. Systemic effects of TC use include hypothalamic-pituitary-adrenal axis suppression, Cushing syndrome, and osteonecrosis of the femoral head.^16-18 These systemic effects with TC use are rare unless treatment is for disease involving greater than 20% BSA or occlusion for more than 4 weeks.

Calcineurin Inhibitors—Calcineurin inhibitors inhibit calcineurin phosphorylation and T-cell activation, subsequently decreasing the expression of proinflammatory cytokines. Currently, they are not approved by the US Food and Drug Administration to treat psoriasis but have demonstrated efficacy in randomized control trials (RCTs) for facial and intertriginous psoriasis. In RCTs, 71% of patients using pimecrolimus cream 0.1% twice daily for 8 weeks achieved an investigator global assessment score of clear (0) or almost clear (1) compared with 21% of placebo-treated patients (N=57).¹⁹ Other trials have shown that 65% of patients receiving tacrolimus ointment 0.1% for 8 weeks achieved an investigator global assessment score of 0 or 1 compared with 31% of placebo-treated patients (N=167).²⁰ Because of their efficacy in RCTs, CNIs commonly are used off label to treat psoriasis.

The most common adverse effects with CNI use are burning, pruritus, and flushing with alcohol ingestion (Table 1). Additionally, CNIs have a black box warning that use may increase the risk for malignancy, but this risk has not been demonstrated with topical use in humans.²¹Vitamin D Analogues—The class of vitamin D analogues—calcipotriol/calcipotriene and calcitriol—frequently are used to treat psoriasis. Vitamin D analogues exert their beneficial effects by inhibiting keratinocyte proliferation and enhancing keratinocyte differentiation. They also are ideal for long-term use (up to 52 weeks) in mild to moderate psoriasis and can be used in combination with class 2 and 3 TCs. There is a level A recommendation that supports the use of combination therapy with calcipotriol and TCs for the treatment of mild to moderate psoriasis.

For severe psoriasis, many studies have investigated the efficacy of combination therapy with vitamin D analogues and systemic treatments. Combination therapy with calcipotriol and methotrexate or calcipotriol and acitretin are effective treatment regimens with level A recommendations. Calcipotriol–betamethasone dipropionate ointment in combination with low-dose cyclosporine is an alternative option with a level B recommendation. Because vitamin D analogues are inactivated by UVA and UVB radiation, clinicians should advise their patients to use vitamin D analogues after receiving UVB phototherapy.²²

Common adverse effects of vitamin D analogues include burning, pruritus, erythema, and dryness (Table 1). Hypercalcemia and parathyroid hormone suppression are extremely rare unless treatment occurs over a large surface area (>30% BSA) or the patient has concurrent renal disease or impairments in calcium metabolism.

Tazarotene—Tazarotene is a topical retinoid that acts by decreasing keratinocyte proliferation, facilitating keratinocyte differentiation, and inhibiting inflammation. Patients with mild to moderate psoriasis are recommended to receive tazarotene treatment for 8 to 12 weeks. In several RCTs, tazarotene gel 0.1% and tazarotene cream 0.1% and 0.05% achieved treatment success in treating plaque psoriasis.^23,24

For increased efficacy, clinicians can recommend combination therapy with tazarotene and a TC. Combination therapy with tazarotene and a mid- or high-potency TC for 8 to 16 weeks has been shown to be more effective than treatment with tazarotene alone.²⁵ Thus, there is a level A recommendation for use of this combination to treat mild to moderate psoriasis. Agents used in combination therapy work synergistically to decrease the length of treatment and increase the duration of remission. The frequency of adverse effects, such as irritation from tazarotene and skin atrophy from TCs, also are reduced.²⁶ Combination therapy with tazarotene and narrowband UVB (NB-UVB) is another effective option that requires less UV radiation than NB-UVB alone because of the synergistic effects of both treatment modalities.²⁷ Clinicians should counsel patients on the adverse effects of tazarotene, which include local irritation, burning, pruritus, and erythema (Table 1).

Emollients—Emollients are nonmedicated moisturizers that decrease the amount of transepidermal water loss. There is a level B recommendation for use of emollients and TCs in combination for 4 to 8 weeks to treat psoriasis. In fact, combination therapy with mometasone and emollients has demonstrated greater improvement in symptoms of palmoplantar psoriasis (ie, erythema, desquamation, infiltration, BSA involvement) than mometasone alone.²⁸ Emollients are safe options that can be used on all areas of the body and during pregnancy and lactation. Although adverse effects of emollients are rare, clinicians should counsel patients on the risk for contact dermatitis if specific allergies to ingredients/fragrances exist (Table 1).

Salicylic Acid—Salicylic acid is a topical keratolytic that can be used to treat psoriatic plaques. Use of salicylic acid for 8 to 16 weeks has been shown to be effective for mild to moderate psoriasis. Combination therapy of salicylic acid and TCs in patients with 20% or less BSA affected is a safe and effective option with a level B recommendation. Combination therapy with salicylic acid and calcipotriene, however, should be avoided because calcipotriene is inactivated by salicylic acid. It also is recommended that salicylic acid application follow phototherapy when both treatment modalities are used in combination.^29,30 Clinicians should be cautious about using salicylic acid in patients with renal or hepatic disease because of the increased risk for salicylate toxicity (Table 1).

Anthralin—Anthralin is a synthetic hydrocarbon derivative that has been shown to reduce inflammation and normalize keratinocyte proliferation through an unknown mechanism. It is recommended that patients with mild to moderate psoriasis receive anthralin treatment for 8 to 12 weeks, with a maximum application time of 2 hours per day. Combination therapy of excimer laser and anthralin has been shown to be more effective in treating psoriasis than anthralin alone.³¹ Therefore, clinicians have the option of including excimer laser therapy for additional disease control. Anthralin should be avoided on the face, flexural regions, and highly visible areas because of potential skin staining (Table 1). Other adverse effects include application-site burning and erythema.

Coal Tar—Coal tar is a heterogenous mixture of aromatic hydrocarbons that is an effective treatment of psoriasis because of its inherent anti-inflammatory and keratoplastic properties. There is high-quality evidence supporting a level A recommendation for coal tar use in mild to moderate psoriasis. Combination therapy with NB-UVB and coal tar (also known as Goeckerman therapy) is a recommended treatment option with a quicker onset of action and improved outcomes compared with NB-UVB therapy alone.^32,33 Adverse events of coal tar include application-site irritation, folliculitis, contact dermatitis, phototoxicity, and skin pigmentation (Table 1).

Conclusion

Topical medications are versatile treatment options that can be utilized as monotherapy or adjunct therapy for mild to severe psoriasis. Benefits of topical agents include minimal required monitoring, few contraindications, and direct localized effect on plaques. Therefore, side effects with topical agent use rarely are systemic. Medication interactions are less of a concern with topical therapies; thus, they have better safety profiles compared with systemic therapies. This clinical review summarizes the recently published evidence-based guidelines from the AAD and NPF on the use of topical agents in psoriasis and may be a useful guiding framework for clinicians in their everyday practice.

Psoriasis is a chronic inflammatory skin disease characterized by erythematous scaly plaques that can invoke substantial pain, pruritus, and quality-of-life disturbance in patients. Topical therapies are the most commonly used medications for treating psoriasis, with one study (N = 128,308) showing that more than 85% of patients with psoriasis were managed solely with topical medications. ¹ For patients with mild to moderate psoriasis, topical agents alone may be able to control disease completely. For those with more severe disease, topical agents are used adjunctively with systemic or biologic agents to optimize disease control in localized areas.

The American Academy of Dermatology (AAD) and National Psoriasis Foundation (NPF) published guidelines in 2020 for managing psoriasis with topical agents in adults.² This review presents the most up-to-date clinical recommendations for topical agent use in adult patients with psoriasis and elaborates on each drug’s pharmacologic and safety profile. Specifically, evidence-based treatment recommendations for topical steroids, calcineurin inhibitors (CNIs), vitamin D analogues, retinoids (tazarotene), emollients, keratolytics (salicylic acid), anthracenes (anthralin), and keratoplastics (coal tar) will be addressed (Table 1). Recommendations for combination therapy with other treatment modalities including UVB light therapy, biologics, and systemic nonbiologic agents also will be discussed.

Selecting a Topical Agent Based on Disease Localization

When treating patients with psoriasis with topical therapies, clinicians should take into consideration drug potency, as it determines how effective a treatment will be in penetrating the skin barrier. Plaque characteristics, such as distribution (localized vs widespread), anatomical localization (flexural, scalp, palms/soles/nails), size (large vs small), and thickness (thick vs thin), not only influence treatment effectiveness but also the incidence of drug-related adverse events. Furthermore, preferred topical therapies are tailored to each patient based on disease characteristics and activity. Coal tar and anthralin have been used less frequently than other topical therapies for psoriasis because of their undesirable side-effect profiles (Table 1).³

Face and Intertriginous Regions—The face and intertriginous areas are sensitive because skin tends to be thin in these regions. Emollients are recommended for disease in these locations given their safety and flexibility in use for most areas. Conversely, anthralin should be avoided on the face, intertriginous areas, and even highly visible locations because of the potential for skin staining. Low-potency corticosteroids also have utility in psoriasis distributed on the face and intertriginous regions. Additionally, application of steroids around the eyes should be cautioned because topical steroids can induce ocular complications such as glaucoma and cataracts in rare circumstances.⁴

Off-label use of CNIs for psoriasis on the face and intertriginous areas also is effective. Currently, there is a level B recommendation for off-label use of 0.1% tacrolimus for up to 8 weeks for inverse psoriasis or psoriasis on the face. Off-label use of pimecrolimus for 4 to 8 weeks also can be considered for inverse psoriasis. Combination therapy consisting of hydrocortisone with calcipotriol ointment is another effective regimen.⁵ One study also suggested that use of crisaborole for 4 to 8 weeks in intertriginous psoriasis can be effective and well tolerated.⁶

Scalp—The vehicle of medication administration is especially important in hair-bearing areas such as the scalp, as these areas are challenging for medication application and patient adherence. Thus, patient preferences for the vehicle must be considered. Several studies have been conducted to assess preference for various vehicles in scalp psoriasis. A foam or solution may be preferable to ointments, gels, or creams.⁷ Gels may be preferred over ointments.⁸ There is a level A recommendation supporting the use of class 1 to 7 topical steroids for a minimum of 4 weeks as initial and maintenance treatment of scalp psoriasis. The highest level of evidence (level A) also supports the use of calcipotriol foam or combination therapy of calcipotriol–betamethasone dipropionate gel for 4 to 12 weeks as treatment of mild to moderate scalp psoriasis.

Nails—Several options for topical medications have been recommended for the treatment of nail psoriasis. Currently, there is a level B recommendation for the use of tazarotene for the treatment of nail psoriasis. Another effective regimen is combination therapy with vitamin D analogues and betamethasone dipropionate.⁹ Topical steroid use for nail psoriasis should be limited to 12 weeks because of the risk for bone atrophy with chronic steroid use.

Palmoplantar—The palms and soles have a thicker epidermal layer than other areas of the body. As a result, class 1 corticosteroids can be used for palmoplantar psoriasis for more than 4 weeks with vigilant monitoring for adverse effects such as skin atrophy, tachyphylaxis, or tinea infection. Tazarotene also has been shown to be helpful in treating palmoplantar psoriasis.

Resistant Disease—Intralesional steroids are beneficial treatment options for recalcitrant psoriasis in glabrous areas, as well as for palmoplantar, nail, and scalp psoriasis. Up to 10 mg/mL of triamcinolone acetonide used every 3 to 4 weeks is an effective regimen.¹⁰Pregnancy/Breastfeeding—Women of childbearing potential have additional safety precautions that should be considered during medication selection. Emollients have been shown to be safe during pregnancy and lactation. Currently, there is little known about CNI use during pregnancy. During lactation, CNIs can be used by breastfeeding mothers in most areas, excluding the breasts. Evaluation of the safety of anthralin and vitamin D analogues during pregnancy and lactation have not been studied. For these agents, dermatologists need to use their clinical judgment to weigh the risks and benefits of medication, particularly in patients requiring occlusion, higher medication doses, or treatment over a large surface area. Salicylic acid should be used with caution in pregnant and breastfeeding mothers because it is a pregnancy category C drug. Lower-potency corticosteroids may be used with caution during pregnancy and breastfeeding. More potent corticosteroids and coal tar, however, should be avoided. Similarly, tazarotene use is contraindicated in pregnancy. According to the US Food and Drug Administration labels for all forms of topical tazarotene, a pregnancy test must be obtained 2 weeks prior to tazarotene treatment initiation in women of childbearing potential because of the risk for serious fetal malformations and toxicity.

Recommendations, Risks, and Benefits of Topical Therapy for the Management of Psoriasis

Topical Corticosteroids—Topical corticosteroids (TCs) are widely used for inflammatory skin conditions and are available in a variety of strengths (Table 2). They are thought to exert their action by regulating the gene transcription of proinflammatory mediators. For psoriasis, steroids are recommended for 2 to 4 weeks, depending on disease severity. Although potent and superpotent steroids are more effective than mild- to moderate-strength TCs, use of lower-potency TCs may be warranted depending on disease distribution and localization.¹¹ For treatment of psoriasis with no involvement of the intertriginous areas, use of class 1 to 5 TCs for up to 4 weeks is recommended.

For moderate to severe psoriasis with 20% or less body surface area (BSA) affected, combination therapy consisting of mometasone and salicylic acid has been shown to be more effective than mometasone alone.^12,13 There currently is a level A recommendation for the use of combination therapy with class 1 TCs and etanercept for 12 weeks in patients with moderate to severe psoriasis who require both systemic and topical therapies for disease control. Similarly, combination therapy with infliximab and high-potency TCs has a level B recommendation to enhance efficacy for the treatment of moderate to severe psoriasis.¹⁴ High-quality studies on the use of TCs with anti–IL-12/IL-23, anti–IL-23, and anti–IL-17 currently are unavailable, but the combination is not expected to be unsafe.^14,15 Combination therapy of betamethasone dipropionate ointment and low-dose cyclosporine is an alternative regimen with a level B recommendation.

The most common adverse effects with use of TCs are skin thinning and atrophy, telangiectasia, and striae (Table 1). With clinical improvement of disease, it is recommended that clinicians taper TCs to prevent rebound effect. To decrease TC-related adverse effects, clinicians should use combination therapy with steroid-sparing agents for disease maintenance, transition to lower-potency corticosteroids, or use intermittent steroid therapy. Systemic effects of TC use include hypothalamic-pituitary-adrenal axis suppression, Cushing syndrome, and osteonecrosis of the femoral head.^16-18 These systemic effects with TC use are rare unless treatment is for disease involving greater than 20% BSA or occlusion for more than 4 weeks.

Calcineurin Inhibitors—Calcineurin inhibitors inhibit calcineurin phosphorylation and T-cell activation, subsequently decreasing the expression of proinflammatory cytokines. Currently, they are not approved by the US Food and Drug Administration to treat psoriasis but have demonstrated efficacy in randomized control trials (RCTs) for facial and intertriginous psoriasis. In RCTs, 71% of patients using pimecrolimus cream 0.1% twice daily for 8 weeks achieved an investigator global assessment score of clear (0) or almost clear (1) compared with 21% of placebo-treated patients (N=57).¹⁹ Other trials have shown that 65% of patients receiving tacrolimus ointment 0.1% for 8 weeks achieved an investigator global assessment score of 0 or 1 compared with 31% of placebo-treated patients (N=167).²⁰ Because of their efficacy in RCTs, CNIs commonly are used off label to treat psoriasis.

The most common adverse effects with CNI use are burning, pruritus, and flushing with alcohol ingestion (Table 1). Additionally, CNIs have a black box warning that use may increase the risk for malignancy, but this risk has not been demonstrated with topical use in humans.²¹Vitamin D Analogues—The class of vitamin D analogues—calcipotriol/calcipotriene and calcitriol—frequently are used to treat psoriasis. Vitamin D analogues exert their beneficial effects by inhibiting keratinocyte proliferation and enhancing keratinocyte differentiation. They also are ideal for long-term use (up to 52 weeks) in mild to moderate psoriasis and can be used in combination with class 2 and 3 TCs. There is a level A recommendation that supports the use of combination therapy with calcipotriol and TCs for the treatment of mild to moderate psoriasis.

For severe psoriasis, many studies have investigated the efficacy of combination therapy with vitamin D analogues and systemic treatments. Combination therapy with calcipotriol and methotrexate or calcipotriol and acitretin are effective treatment regimens with level A recommendations. Calcipotriol–betamethasone dipropionate ointment in combination with low-dose cyclosporine is an alternative option with a level B recommendation. Because vitamin D analogues are inactivated by UVA and UVB radiation, clinicians should advise their patients to use vitamin D analogues after receiving UVB phototherapy.²²

Common adverse effects of vitamin D analogues include burning, pruritus, erythema, and dryness (Table 1). Hypercalcemia and parathyroid hormone suppression are extremely rare unless treatment occurs over a large surface area (>30% BSA) or the patient has concurrent renal disease or impairments in calcium metabolism.

Tazarotene—Tazarotene is a topical retinoid that acts by decreasing keratinocyte proliferation, facilitating keratinocyte differentiation, and inhibiting inflammation. Patients with mild to moderate psoriasis are recommended to receive tazarotene treatment for 8 to 12 weeks. In several RCTs, tazarotene gel 0.1% and tazarotene cream 0.1% and 0.05% achieved treatment success in treating plaque psoriasis.^23,24

For increased efficacy, clinicians can recommend combination therapy with tazarotene and a TC. Combination therapy with tazarotene and a mid- or high-potency TC for 8 to 16 weeks has been shown to be more effective than treatment with tazarotene alone.²⁵ Thus, there is a level A recommendation for use of this combination to treat mild to moderate psoriasis. Agents used in combination therapy work synergistically to decrease the length of treatment and increase the duration of remission. The frequency of adverse effects, such as irritation from tazarotene and skin atrophy from TCs, also are reduced.²⁶ Combination therapy with tazarotene and narrowband UVB (NB-UVB) is another effective option that requires less UV radiation than NB-UVB alone because of the synergistic effects of both treatment modalities.²⁷ Clinicians should counsel patients on the adverse effects of tazarotene, which include local irritation, burning, pruritus, and erythema (Table 1).

Emollients—Emollients are nonmedicated moisturizers that decrease the amount of transepidermal water loss. There is a level B recommendation for use of emollients and TCs in combination for 4 to 8 weeks to treat psoriasis. In fact, combination therapy with mometasone and emollients has demonstrated greater improvement in symptoms of palmoplantar psoriasis (ie, erythema, desquamation, infiltration, BSA involvement) than mometasone alone.²⁸ Emollients are safe options that can be used on all areas of the body and during pregnancy and lactation. Although adverse effects of emollients are rare, clinicians should counsel patients on the risk for contact dermatitis if specific allergies to ingredients/fragrances exist (Table 1).

Salicylic Acid—Salicylic acid is a topical keratolytic that can be used to treat psoriatic plaques. Use of salicylic acid for 8 to 16 weeks has been shown to be effective for mild to moderate psoriasis. Combination therapy of salicylic acid and TCs in patients with 20% or less BSA affected is a safe and effective option with a level B recommendation. Combination therapy with salicylic acid and calcipotriene, however, should be avoided because calcipotriene is inactivated by salicylic acid. It also is recommended that salicylic acid application follow phototherapy when both treatment modalities are used in combination.^29,30 Clinicians should be cautious about using salicylic acid in patients with renal or hepatic disease because of the increased risk for salicylate toxicity (Table 1).

Anthralin—Anthralin is a synthetic hydrocarbon derivative that has been shown to reduce inflammation and normalize keratinocyte proliferation through an unknown mechanism. It is recommended that patients with mild to moderate psoriasis receive anthralin treatment for 8 to 12 weeks, with a maximum application time of 2 hours per day. Combination therapy of excimer laser and anthralin has been shown to be more effective in treating psoriasis than anthralin alone.³¹ Therefore, clinicians have the option of including excimer laser therapy for additional disease control. Anthralin should be avoided on the face, flexural regions, and highly visible areas because of potential skin staining (Table 1). Other adverse effects include application-site burning and erythema.

Coal Tar—Coal tar is a heterogenous mixture of aromatic hydrocarbons that is an effective treatment of psoriasis because of its inherent anti-inflammatory and keratoplastic properties. There is high-quality evidence supporting a level A recommendation for coal tar use in mild to moderate psoriasis. Combination therapy with NB-UVB and coal tar (also known as Goeckerman therapy) is a recommended treatment option with a quicker onset of action and improved outcomes compared with NB-UVB therapy alone.^32,33 Adverse events of coal tar include application-site irritation, folliculitis, contact dermatitis, phototoxicity, and skin pigmentation (Table 1).

Conclusion

Topical medications are versatile treatment options that can be utilized as monotherapy or adjunct therapy for mild to severe psoriasis. Benefits of topical agents include minimal required monitoring, few contraindications, and direct localized effect on plaques. Therefore, side effects with topical agent use rarely are systemic. Medication interactions are less of a concern with topical therapies; thus, they have better safety profiles compared with systemic therapies. This clinical review summarizes the recently published evidence-based guidelines from the AAD and NPF on the use of topical agents in psoriasis and may be a useful guiding framework for clinicians in their everyday practice.

When COVID-19 emerged in March 2020, physicians were forced to evaluate the potential impacts of the pandemic on our patients and the conditions that we treat. For dermatologists, psoriasis came into particular focus, as many patients were being treated with biologic therapies. The initial concern was that these biologics might render our patients more susceptible to both COVID-19 infection and/or a more severe disease course.

In early 2020, the National Psoriasis Foundation (NPF) presented its own recommendations for treating patients with psoriatic disease during the pandemic.¹ Some highlights included the following¹:

• At the time, it was stipulated that patients with COVID-19 infection should stop taking a biologic.

• Psoriasis patients in high-risk groups (eg, concomitant systemic disease) should discuss with their dermatologist if their therapeutic regimen should be continued or altered.

• Patients taking oral immunosuppressive therapy may be at greater risk for COVID-19 infection, though there is no strong COVID-19–related evidence to provide specific guidelines or risk level.

In May 2020, the NPF COVID-19 Task Force was formed. This group—chaired by dermatologist Joel M. Gelfand, MD, MSCE (Philadelphia, Pennsylvania), and rheumatologist Christopher T. Ritchlin, MD, MPH (Rochester, New York)—was comprised of members from both the NPF Medical Board and Scientific Advisory Committee in dermatology, rheumatology, infectious disease, and critical care. The NPF COVID-19 Task Force has been critical in keeping the dermatology community apprised of the latest scientific thinking related to COVID-19 and publishing guidance statements that are updated and amended on a regular basis as new data becomes available.² Key recommendations most relevant to the daily care of patients with psoriatic disease included the following²:

• Patients with psoriasis and/or psoriatic arthritis have similar rates of SARS-CoV-2 infection and COVID-19 outcomes as the general population based on existing data, with some exceptions.

• Therapies for psoriasis and/or psoriatic arthritis do not meaningfully alter the risk for acquiring SARS-CoV-2 infection or having worse COVID-19 outcomes.

• Patients should continue their biologic or oral therapies for psoriasis and/or psoriatic arthritis in most cases, unless they become infected with SARS-CoV-2.

• Chronic systemic steroid use for psoriatic disease in the setting of acute infection with COVID-19 may be associated with worse outcomes; however, steroids may improve outcomes for COVID-19 when initiated in hospitalized patients who require oxygen therapy.

• When local restrictions or pandemic conditions limit the ability for in-person visits, offer telemedicine to manage patients.

• Patients with psoriatic disease who do not have contraindications to vaccination should receive a messenger RNA (mRNA)–based COVID-19 vaccine and boosters, based on federal, state, and local guidance. Systemic medications for psoriasis or psoriatic arthritis are not a contraindication to the mRNA-based COVID-19 vaccine. 

• Patients who are to receive an mRNA-based COVID-19 vaccine should continue their biologic or oral therapies for psoriasis and/or psoriatic arthritis in most cases.

• The use of hydroxychloroquine, chloroquine, and ivermectin is not suggested for the prevention or treatment of COVID-19 disease.

These guidelines have been critical in addressing some of the most pressing issues in psoriasis patient care, particularly the susceptibility to COVID-19, the role of psoriasis therapies in initial infection and health outcomes, and issues related to the administration of vaccines in those on systemic therapies. Based on these recommendations, we have been given a solid foundation that our current standard of care can (for the most part) continue with the continued presence of COVID-19 in our society. I encourage all providers to familiarize themselves with the NPF COVID-19 Task Force guidelines and keep abreast of updates as they become available (https://www.psoriasis.org/covid-19-task-force-guidance-statements/).

When COVID-19 emerged in March 2020, physicians were forced to evaluate the potential impacts of the pandemic on our patients and the conditions that we treat. For dermatologists, psoriasis came into particular focus, as many patients were being treated with biologic therapies. The initial concern was that these biologics might render our patients more susceptible to both COVID-19 infection and/or a more severe disease course.

In early 2020, the National Psoriasis Foundation (NPF) presented its own recommendations for treating patients with psoriatic disease during the pandemic.¹ Some highlights included the following¹:

• At the time, it was stipulated that patients with COVID-19 infection should stop taking a biologic.

• Psoriasis patients in high-risk groups (eg, concomitant systemic disease) should discuss with their dermatologist if their therapeutic regimen should be continued or altered.

• Patients taking oral immunosuppressive therapy may be at greater risk for COVID-19 infection, though there is no strong COVID-19–related evidence to provide specific guidelines or risk level.

In May 2020, the NPF COVID-19 Task Force was formed. This group—chaired by dermatologist Joel M. Gelfand, MD, MSCE (Philadelphia, Pennsylvania), and rheumatologist Christopher T. Ritchlin, MD, MPH (Rochester, New York)—was comprised of members from both the NPF Medical Board and Scientific Advisory Committee in dermatology, rheumatology, infectious disease, and critical care. The NPF COVID-19 Task Force has been critical in keeping the dermatology community apprised of the latest scientific thinking related to COVID-19 and publishing guidance statements that are updated and amended on a regular basis as new data becomes available.² Key recommendations most relevant to the daily care of patients with psoriatic disease included the following²:

• Patients with psoriasis and/or psoriatic arthritis have similar rates of SARS-CoV-2 infection and COVID-19 outcomes as the general population based on existing data, with some exceptions.

• Therapies for psoriasis and/or psoriatic arthritis do not meaningfully alter the risk for acquiring SARS-CoV-2 infection or having worse COVID-19 outcomes.

• Patients should continue their biologic or oral therapies for psoriasis and/or psoriatic arthritis in most cases, unless they become infected with SARS-CoV-2.

• Chronic systemic steroid use for psoriatic disease in the setting of acute infection with COVID-19 may be associated with worse outcomes; however, steroids may improve outcomes for COVID-19 when initiated in hospitalized patients who require oxygen therapy.

• When local restrictions or pandemic conditions limit the ability for in-person visits, offer telemedicine to manage patients.

• Patients with psoriatic disease who do not have contraindications to vaccination should receive a messenger RNA (mRNA)–based COVID-19 vaccine and boosters, based on federal, state, and local guidance. Systemic medications for psoriasis or psoriatic arthritis are not a contraindication to the mRNA-based COVID-19 vaccine. 

• Patients who are to receive an mRNA-based COVID-19 vaccine should continue their biologic or oral therapies for psoriasis and/or psoriatic arthritis in most cases.

• The use of hydroxychloroquine, chloroquine, and ivermectin is not suggested for the prevention or treatment of COVID-19 disease.

These guidelines have been critical in addressing some of the most pressing issues in psoriasis patient care, particularly the susceptibility to COVID-19, the role of psoriasis therapies in initial infection and health outcomes, and issues related to the administration of vaccines in those on systemic therapies. Based on these recommendations, we have been given a solid foundation that our current standard of care can (for the most part) continue with the continued presence of COVID-19 in our society. I encourage all providers to familiarize themselves with the NPF COVID-19 Task Force guidelines and keep abreast of updates as they become available (https://www.psoriasis.org/covid-19-task-force-guidance-statements/).

When COVID-19 emerged in March 2020, physicians were forced to evaluate the potential impacts of the pandemic on our patients and the conditions that we treat. For dermatologists, psoriasis came into particular focus, as many patients were being treated with biologic therapies. The initial concern was that these biologics might render our patients more susceptible to both COVID-19 infection and/or a more severe disease course.

In early 2020, the National Psoriasis Foundation (NPF) presented its own recommendations for treating patients with psoriatic disease during the pandemic.¹ Some highlights included the following¹:

• At the time, it was stipulated that patients with COVID-19 infection should stop taking a biologic.

• Psoriasis patients in high-risk groups (eg, concomitant systemic disease) should discuss with their dermatologist if their therapeutic regimen should be continued or altered.

• Patients taking oral immunosuppressive therapy may be at greater risk for COVID-19 infection, though there is no strong COVID-19–related evidence to provide specific guidelines or risk level.

In May 2020, the NPF COVID-19 Task Force was formed. This group—chaired by dermatologist Joel M. Gelfand, MD, MSCE (Philadelphia, Pennsylvania), and rheumatologist Christopher T. Ritchlin, MD, MPH (Rochester, New York)—was comprised of members from both the NPF Medical Board and Scientific Advisory Committee in dermatology, rheumatology, infectious disease, and critical care. The NPF COVID-19 Task Force has been critical in keeping the dermatology community apprised of the latest scientific thinking related to COVID-19 and publishing guidance statements that are updated and amended on a regular basis as new data becomes available.² Key recommendations most relevant to the daily care of patients with psoriatic disease included the following²:

• Patients with psoriasis and/or psoriatic arthritis have similar rates of SARS-CoV-2 infection and COVID-19 outcomes as the general population based on existing data, with some exceptions.

• Therapies for psoriasis and/or psoriatic arthritis do not meaningfully alter the risk for acquiring SARS-CoV-2 infection or having worse COVID-19 outcomes.

• Patients should continue their biologic or oral therapies for psoriasis and/or psoriatic arthritis in most cases, unless they become infected with SARS-CoV-2.

• Chronic systemic steroid use for psoriatic disease in the setting of acute infection with COVID-19 may be associated with worse outcomes; however, steroids may improve outcomes for COVID-19 when initiated in hospitalized patients who require oxygen therapy.

• When local restrictions or pandemic conditions limit the ability for in-person visits, offer telemedicine to manage patients.

• Patients with psoriatic disease who do not have contraindications to vaccination should receive a messenger RNA (mRNA)–based COVID-19 vaccine and boosters, based on federal, state, and local guidance. Systemic medications for psoriasis or psoriatic arthritis are not a contraindication to the mRNA-based COVID-19 vaccine. 

• Patients who are to receive an mRNA-based COVID-19 vaccine should continue their biologic or oral therapies for psoriasis and/or psoriatic arthritis in most cases.

• The use of hydroxychloroquine, chloroquine, and ivermectin is not suggested for the prevention or treatment of COVID-19 disease.

These guidelines have been critical in addressing some of the most pressing issues in psoriasis patient care, particularly the susceptibility to COVID-19, the role of psoriasis therapies in initial infection and health outcomes, and issues related to the administration of vaccines in those on systemic therapies. Based on these recommendations, we have been given a solid foundation that our current standard of care can (for the most part) continue with the continued presence of COVID-19 in our society. I encourage all providers to familiarize themselves with the NPF COVID-19 Task Force guidelines and keep abreast of updates as they become available (https://www.psoriasis.org/covid-19-task-force-guidance-statements/).