Cutis

Just when you might have thought dermatologic therapies were peaking, along came another banner year in atopic dermatitis (AD). Last year we saw the landmark launch of dupilumab, the first US Food and Drug Administration (FDA)–approved biologic therapy for AD. Dupilumab addresses a novel mechanism of AD in adults by blocking IL-4 and IL-13, which both play a central role in the type 2 helper T cell (T_H2) axis on the dual development of barrier-impaired skin and aberrant immune response including IgE to cutaneous aggravating agents with resultant inflammation. Additional information has shown direct effects to reduce itch in AD.¹ A 12-week study of dupilumab monotherapy showed that 85% (47/55) of treated patients had at least a 50% reduction in Eczema Area and Severity Index (EASI) score and 40% (22/55) were clear or almost clear on the investigator global assessment. With concomitant corticosteroid therapy, 100% of patients achieved EASI-50.² Also notable, 2017 ushered in the appearance of a novel iteration of the 30-year-old concept of phosphodiesterase inhibition with the approval of the topical agent crisaborole for AD treatment in patients 2 years and older, which has been shown to be effective in both children and adults.^3,4 However, despite these leaps of advancement in the care of AD, by no means has the condition been cured.

Atopic dermatitis has remained an incurable disease due to many factors: (1) variable immunologic and environmental triggers and patient disease course; (2) intolerance to therapeutic agents, including an enhanced sense of stinging and/or reactivity; (3) poor access to novel therapies among underserved patient populations; (4) lack of available data and information on variable treatment response by ethnicity and race; and (5) the absence of biologic treatments for severe childhood AD to modify long-term recurrence and progression of atopy, which is probably the most important issue, as the majority of AD cases start in children 5 years and younger.

Instituting a treatment today to provide children with disease-free skin for a lifetime truly is the Holy Grail in pediatric dermatology. To aid in the progress toward this goal, a deeper understanding of the manifestation of pediatric versus adult AD is now being investigated. It is clear that with adult chronicity, type 1 helper T cell (T_H1) axis activity and prolonged defects are triggered in barrier maturation; however, recent data have started to demonstrate that the youngest patients have different issues in lipid maturation and lack T_H1 activation. In particular, fatty acyl-CoA reductase 2 and fatty acid 2-hydroxylase is preferentially downregulated in children.⁵ It appears that the young immune system may be ripe for immune modification, which previously has been demonstrated with wild-type viral infections of varicella in children.⁶ However, future research will focus on what kind of tweaks to the immune system are required.

To encapsulate the AD pipeline, we will review drug trials that are in active recruitment as well as recently published data, which constitute an exciting group full of modifications of current therapies and agents with novel mechanisms of action. Paller et al⁷ and Renert-Yuval and Guttman-Yassky⁸ published detailed analyses of the recent pipeline for systemic therapies. In the realm of systemic agents, the main therapies in development are alternative immunomodulation mechanisms and biologic agents targeting a variety of immune checkpoints. Oral treatments and intravenous, intradermal, and subcutaneous injections will offer AD patients a variety of therapeutic options and potentially provide help for the needle-phobic patient.

Therapies targeting new mechanisms of action include Janus kinase (JAK) inhibitors, which have shown promising results for alopecia areata and vitiligo vulgaris. These agents may create selective modification of the immune system and are being tested topically and orally (Clinicaltrials.gov identifier NCT03011892). One phase 2a trial of topical tofacitinib showed superior efficacy over placebo, supporting class benefit, but drug development has been stopped for this agent.⁹ Another recent phase 2 trial of systemic baricitinib plus topical corticosteroids for treatment of AD demonstrated good efficacy (ie, EASI-50) versus topical corticosteroids alone (61% vs 37%).¹⁰

Another mechanism that currently is being studied includes a topical IL-4 and IL-13 inhibitor, which would hopefully mimic the efficacy of dupilumab, antioxidant therapies, and antimicrobials (NCT03351777, NCT03381625, NCT02910011). A new G protein–coupled receptor 19 (also known as membrane-type bile acid receptor or TGR5 receptor) agonist represents a novel mechanistic approach (NCT03492398), as does the liver X receptors (LXR) agonist, which is intended to enhance barrier function and thereby reduce inflammation (NCT03175354). Ammonia-oxidizing bacteria are being tested with a putative mechanism of increased nitic oxide release (NCT03235024), while nitric oxide alone also is being tested (NCT03431610). Although most of the aforementioned agents are in phase 1 and 2 trials, excitement is mounting over a phase 3 trial for IDP-124 lotion (NCT03058783), though extensive data have not yet been released from the manufacturer, as well as a phase 4 trial for crisaborole in infants and toddlers aged 3 to 24 months (NCT03356977). If the trial is successful and the drug is approved, crisaborole would be the first FDA-approved topical nonsteroidal prescription agent for that age group. Interestingly, 2 systemic agents are being tested in children younger than 18 years with AD, including a phase 3 trial of PF-04965842, a JAK1 selective inhibitor, in children aged 12 years and older (NCT03575871), and a phase 4 trial of omalizumab in children aged 4 to 19 years (NCT02300701). Omalizumab is an anti-IgE antibody with indications for allergic asthma and chronic idiopathic urticaria.

Data on the outcome of a phase 3 trial of dupilumab in adolescents has been released but not yet published by the manufacturer and shows promising results in children aged 12 to 17 years, both in reduction of EASI score and in achieving clear or almost clear skin.¹¹ Interestingly, limited data available from a press release reported similar results with dupilumab injection every 2 weeks versus every 4 weeks, which may give alternative dosing regimens in this age group once approved¹¹; however, publication has yet to occur for the latter data.

Other mechanistic agents include blockade of cytokines and interleukins, particularly those involved in type 2 helper T cell (T_H2) activity, such as thymic stromal lymphopoietin (a cytokine), as well as targeted single inhibition of IL-4, IL-5, IL-13, and IL-31 and/or their receptors. Nemolizumab, an anti–IL-31 receptor A antibody, is showing promise in the control of AD-associated itch and reduction in EASI scores.¹² Stem cell therapy, anti–OX-40 receptor monoclonal antibody, anti–IL-17C monoclonal antibody, anti–IL-33 monoclonal antibody, and neurokinin-1 receptor antagonist (NCT01941537, NCT03100344, NCT03054428, NCT03160885, NCT02888704, NCT03269773, NCT03568162, NCT03568071, NCT03533751, NCT03568331, NCT03540160) round out the roster of agents entering further trials in AD.

The future of AD therapy is anyone’s guess. Having entered the biologic era with dupilumab, we have a high bar set for efficacy and safety of AD therapies, yet there remains a core group of AD patients who have not yet achieved clearance or refuse injectables; therefore, adjunctive or alternative therapeutics are still needed. Furthermore, we still have not identified who will best benefit long-term from systemic intervention and how to best effect long-term disease control with biologics or novel agents, and choosing the therapy based on patient disease characteristics or serotyping has not yet come of age. It is exciting to think about what next year will bring!

Just when you might have thought dermatologic therapies were peaking, along came another banner year in atopic dermatitis (AD). Last year we saw the landmark launch of dupilumab, the first US Food and Drug Administration (FDA)–approved biologic therapy for AD. Dupilumab addresses a novel mechanism of AD in adults by blocking IL-4 and IL-13, which both play a central role in the type 2 helper T cell (T_H2) axis on the dual development of barrier-impaired skin and aberrant immune response including IgE to cutaneous aggravating agents with resultant inflammation. Additional information has shown direct effects to reduce itch in AD.¹ A 12-week study of dupilumab monotherapy showed that 85% (47/55) of treated patients had at least a 50% reduction in Eczema Area and Severity Index (EASI) score and 40% (22/55) were clear or almost clear on the investigator global assessment. With concomitant corticosteroid therapy, 100% of patients achieved EASI-50.² Also notable, 2017 ushered in the appearance of a novel iteration of the 30-year-old concept of phosphodiesterase inhibition with the approval of the topical agent crisaborole for AD treatment in patients 2 years and older, which has been shown to be effective in both children and adults.^3,4 However, despite these leaps of advancement in the care of AD, by no means has the condition been cured.

Atopic dermatitis has remained an incurable disease due to many factors: (1) variable immunologic and environmental triggers and patient disease course; (2) intolerance to therapeutic agents, including an enhanced sense of stinging and/or reactivity; (3) poor access to novel therapies among underserved patient populations; (4) lack of available data and information on variable treatment response by ethnicity and race; and (5) the absence of biologic treatments for severe childhood AD to modify long-term recurrence and progression of atopy, which is probably the most important issue, as the majority of AD cases start in children 5 years and younger.

Instituting a treatment today to provide children with disease-free skin for a lifetime truly is the Holy Grail in pediatric dermatology. To aid in the progress toward this goal, a deeper understanding of the manifestation of pediatric versus adult AD is now being investigated. It is clear that with adult chronicity, type 1 helper T cell (T_H1) axis activity and prolonged defects are triggered in barrier maturation; however, recent data have started to demonstrate that the youngest patients have different issues in lipid maturation and lack T_H1 activation. In particular, fatty acyl-CoA reductase 2 and fatty acid 2-hydroxylase is preferentially downregulated in children.⁵ It appears that the young immune system may be ripe for immune modification, which previously has been demonstrated with wild-type viral infections of varicella in children.⁶ However, future research will focus on what kind of tweaks to the immune system are required.

To encapsulate the AD pipeline, we will review drug trials that are in active recruitment as well as recently published data, which constitute an exciting group full of modifications of current therapies and agents with novel mechanisms of action. Paller et al⁷ and Renert-Yuval and Guttman-Yassky⁸ published detailed analyses of the recent pipeline for systemic therapies. In the realm of systemic agents, the main therapies in development are alternative immunomodulation mechanisms and biologic agents targeting a variety of immune checkpoints. Oral treatments and intravenous, intradermal, and subcutaneous injections will offer AD patients a variety of therapeutic options and potentially provide help for the needle-phobic patient.

Therapies targeting new mechanisms of action include Janus kinase (JAK) inhibitors, which have shown promising results for alopecia areata and vitiligo vulgaris. These agents may create selective modification of the immune system and are being tested topically and orally (Clinicaltrials.gov identifier NCT03011892). One phase 2a trial of topical tofacitinib showed superior efficacy over placebo, supporting class benefit, but drug development has been stopped for this agent.⁹ Another recent phase 2 trial of systemic baricitinib plus topical corticosteroids for treatment of AD demonstrated good efficacy (ie, EASI-50) versus topical corticosteroids alone (61% vs 37%).¹⁰

Another mechanism that currently is being studied includes a topical IL-4 and IL-13 inhibitor, which would hopefully mimic the efficacy of dupilumab, antioxidant therapies, and antimicrobials (NCT03351777, NCT03381625, NCT02910011). A new G protein–coupled receptor 19 (also known as membrane-type bile acid receptor or TGR5 receptor) agonist represents a novel mechanistic approach (NCT03492398), as does the liver X receptors (LXR) agonist, which is intended to enhance barrier function and thereby reduce inflammation (NCT03175354). Ammonia-oxidizing bacteria are being tested with a putative mechanism of increased nitic oxide release (NCT03235024), while nitric oxide alone also is being tested (NCT03431610). Although most of the aforementioned agents are in phase 1 and 2 trials, excitement is mounting over a phase 3 trial for IDP-124 lotion (NCT03058783), though extensive data have not yet been released from the manufacturer, as well as a phase 4 trial for crisaborole in infants and toddlers aged 3 to 24 months (NCT03356977). If the trial is successful and the drug is approved, crisaborole would be the first FDA-approved topical nonsteroidal prescription agent for that age group. Interestingly, 2 systemic agents are being tested in children younger than 18 years with AD, including a phase 3 trial of PF-04965842, a JAK1 selective inhibitor, in children aged 12 years and older (NCT03575871), and a phase 4 trial of omalizumab in children aged 4 to 19 years (NCT02300701). Omalizumab is an anti-IgE antibody with indications for allergic asthma and chronic idiopathic urticaria.

Data on the outcome of a phase 3 trial of dupilumab in adolescents has been released but not yet published by the manufacturer and shows promising results in children aged 12 to 17 years, both in reduction of EASI score and in achieving clear or almost clear skin.¹¹ Interestingly, limited data available from a press release reported similar results with dupilumab injection every 2 weeks versus every 4 weeks, which may give alternative dosing regimens in this age group once approved¹¹; however, publication has yet to occur for the latter data.

Other mechanistic agents include blockade of cytokines and interleukins, particularly those involved in type 2 helper T cell (T_H2) activity, such as thymic stromal lymphopoietin (a cytokine), as well as targeted single inhibition of IL-4, IL-5, IL-13, and IL-31 and/or their receptors. Nemolizumab, an anti–IL-31 receptor A antibody, is showing promise in the control of AD-associated itch and reduction in EASI scores.¹² Stem cell therapy, anti–OX-40 receptor monoclonal antibody, anti–IL-17C monoclonal antibody, anti–IL-33 monoclonal antibody, and neurokinin-1 receptor antagonist (NCT01941537, NCT03100344, NCT03054428, NCT03160885, NCT02888704, NCT03269773, NCT03568162, NCT03568071, NCT03533751, NCT03568331, NCT03540160) round out the roster of agents entering further trials in AD.

The future of AD therapy is anyone’s guess. Having entered the biologic era with dupilumab, we have a high bar set for efficacy and safety of AD therapies, yet there remains a core group of AD patients who have not yet achieved clearance or refuse injectables; therefore, adjunctive or alternative therapeutics are still needed. Furthermore, we still have not identified who will best benefit long-term from systemic intervention and how to best effect long-term disease control with biologics or novel agents, and choosing the therapy based on patient disease characteristics or serotyping has not yet come of age. It is exciting to think about what next year will bring!

Just when you might have thought dermatologic therapies were peaking, along came another banner year in atopic dermatitis (AD). Last year we saw the landmark launch of dupilumab, the first US Food and Drug Administration (FDA)–approved biologic therapy for AD. Dupilumab addresses a novel mechanism of AD in adults by blocking IL-4 and IL-13, which both play a central role in the type 2 helper T cell (T_H2) axis on the dual development of barrier-impaired skin and aberrant immune response including IgE to cutaneous aggravating agents with resultant inflammation. Additional information has shown direct effects to reduce itch in AD.¹ A 12-week study of dupilumab monotherapy showed that 85% (47/55) of treated patients had at least a 50% reduction in Eczema Area and Severity Index (EASI) score and 40% (22/55) were clear or almost clear on the investigator global assessment. With concomitant corticosteroid therapy, 100% of patients achieved EASI-50.² Also notable, 2017 ushered in the appearance of a novel iteration of the 30-year-old concept of phosphodiesterase inhibition with the approval of the topical agent crisaborole for AD treatment in patients 2 years and older, which has been shown to be effective in both children and adults.^3,4 However, despite these leaps of advancement in the care of AD, by no means has the condition been cured.

Atopic dermatitis has remained an incurable disease due to many factors: (1) variable immunologic and environmental triggers and patient disease course; (2) intolerance to therapeutic agents, including an enhanced sense of stinging and/or reactivity; (3) poor access to novel therapies among underserved patient populations; (4) lack of available data and information on variable treatment response by ethnicity and race; and (5) the absence of biologic treatments for severe childhood AD to modify long-term recurrence and progression of atopy, which is probably the most important issue, as the majority of AD cases start in children 5 years and younger.

Instituting a treatment today to provide children with disease-free skin for a lifetime truly is the Holy Grail in pediatric dermatology. To aid in the progress toward this goal, a deeper understanding of the manifestation of pediatric versus adult AD is now being investigated. It is clear that with adult chronicity, type 1 helper T cell (T_H1) axis activity and prolonged defects are triggered in barrier maturation; however, recent data have started to demonstrate that the youngest patients have different issues in lipid maturation and lack T_H1 activation. In particular, fatty acyl-CoA reductase 2 and fatty acid 2-hydroxylase is preferentially downregulated in children.⁵ It appears that the young immune system may be ripe for immune modification, which previously has been demonstrated with wild-type viral infections of varicella in children.⁶ However, future research will focus on what kind of tweaks to the immune system are required.

To encapsulate the AD pipeline, we will review drug trials that are in active recruitment as well as recently published data, which constitute an exciting group full of modifications of current therapies and agents with novel mechanisms of action. Paller et al⁷ and Renert-Yuval and Guttman-Yassky⁸ published detailed analyses of the recent pipeline for systemic therapies. In the realm of systemic agents, the main therapies in development are alternative immunomodulation mechanisms and biologic agents targeting a variety of immune checkpoints. Oral treatments and intravenous, intradermal, and subcutaneous injections will offer AD patients a variety of therapeutic options and potentially provide help for the needle-phobic patient.

Therapies targeting new mechanisms of action include Janus kinase (JAK) inhibitors, which have shown promising results for alopecia areata and vitiligo vulgaris. These agents may create selective modification of the immune system and are being tested topically and orally (Clinicaltrials.gov identifier NCT03011892). One phase 2a trial of topical tofacitinib showed superior efficacy over placebo, supporting class benefit, but drug development has been stopped for this agent.⁹ Another recent phase 2 trial of systemic baricitinib plus topical corticosteroids for treatment of AD demonstrated good efficacy (ie, EASI-50) versus topical corticosteroids alone (61% vs 37%).¹⁰

Another mechanism that currently is being studied includes a topical IL-4 and IL-13 inhibitor, which would hopefully mimic the efficacy of dupilumab, antioxidant therapies, and antimicrobials (NCT03351777, NCT03381625, NCT02910011). A new G protein–coupled receptor 19 (also known as membrane-type bile acid receptor or TGR5 receptor) agonist represents a novel mechanistic approach (NCT03492398), as does the liver X receptors (LXR) agonist, which is intended to enhance barrier function and thereby reduce inflammation (NCT03175354). Ammonia-oxidizing bacteria are being tested with a putative mechanism of increased nitic oxide release (NCT03235024), while nitric oxide alone also is being tested (NCT03431610). Although most of the aforementioned agents are in phase 1 and 2 trials, excitement is mounting over a phase 3 trial for IDP-124 lotion (NCT03058783), though extensive data have not yet been released from the manufacturer, as well as a phase 4 trial for crisaborole in infants and toddlers aged 3 to 24 months (NCT03356977). If the trial is successful and the drug is approved, crisaborole would be the first FDA-approved topical nonsteroidal prescription agent for that age group. Interestingly, 2 systemic agents are being tested in children younger than 18 years with AD, including a phase 3 trial of PF-04965842, a JAK1 selective inhibitor, in children aged 12 years and older (NCT03575871), and a phase 4 trial of omalizumab in children aged 4 to 19 years (NCT02300701). Omalizumab is an anti-IgE antibody with indications for allergic asthma and chronic idiopathic urticaria.

Data on the outcome of a phase 3 trial of dupilumab in adolescents has been released but not yet published by the manufacturer and shows promising results in children aged 12 to 17 years, both in reduction of EASI score and in achieving clear or almost clear skin.¹¹ Interestingly, limited data available from a press release reported similar results with dupilumab injection every 2 weeks versus every 4 weeks, which may give alternative dosing regimens in this age group once approved¹¹; however, publication has yet to occur for the latter data.

Other mechanistic agents include blockade of cytokines and interleukins, particularly those involved in type 2 helper T cell (T_H2) activity, such as thymic stromal lymphopoietin (a cytokine), as well as targeted single inhibition of IL-4, IL-5, IL-13, and IL-31 and/or their receptors. Nemolizumab, an anti–IL-31 receptor A antibody, is showing promise in the control of AD-associated itch and reduction in EASI scores.¹² Stem cell therapy, anti–OX-40 receptor monoclonal antibody, anti–IL-17C monoclonal antibody, anti–IL-33 monoclonal antibody, and neurokinin-1 receptor antagonist (NCT01941537, NCT03100344, NCT03054428, NCT03160885, NCT02888704, NCT03269773, NCT03568162, NCT03568071, NCT03533751, NCT03568331, NCT03540160) round out the roster of agents entering further trials in AD.

The future of AD therapy is anyone’s guess. Having entered the biologic era with dupilumab, we have a high bar set for efficacy and safety of AD therapies, yet there remains a core group of AD patients who have not yet achieved clearance or refuse injectables; therefore, adjunctive or alternative therapeutics are still needed. Furthermore, we still have not identified who will best benefit long-term from systemic intervention and how to best effect long-term disease control with biologics or novel agents, and choosing the therapy based on patient disease characteristics or serotyping has not yet come of age. It is exciting to think about what next year will bring!

Dermatologists are uniquely equipped amongst clinicians to make bedside diagnoses because of the focus on histopathology and microscopy inherent in our training. This skill is highly valuable in both an inpatient and outpatient setting because it may lead to a rapid diagnosis or be a useful adjunct in the initial clinical decision-making process. Although expert microscopists may be able to garner relevant information from scraping almost any type of lesion, bedside microscopy primarily is used by dermatologists in the United States for consideration of infectious etiologies of a variety of cutaneous manifestations.^1,2

Basic Principles

Lesions that should be considered for bedside microscopic analysis in outpatient settings are scaly lesions, vesiculobullous lesions, inflammatory papules, and pustules¹; microscopic evaluation also can be useful for myriad trichoscopic considerations.^3,4 In some instances, direct visualization of the pathogen is possible (eg, cutaneous fungal infections, demodicidosis, scabetic infections), and in other circumstances reactive changes of keratinocytes or the presence of specific cell types can aid in diagnosis (eg, ballooning degeneration and multinucleation of keratinocytes in herpetic lesions, an abundance of eosinophils in erythema toxicum neonatorum). Different types of media are used to best prepare tissue based on the suspected etiology of the condition.

One major stumbling block for residents when beginning to perform bedside testing is the lack of dimensional understanding of the structures they are searching for; for example, medical students and residents often may mistake fibers for dermatophytes, which typically are much larger than fungal hyphae. Familiarizing oneself with the basic dimensions of different cell types or pathogens in relation to each other (Table) will help further refine the beginner’s ability to effectively search for and identify pathogenic features. This concept is further schematized in Figure 1 to help visualize scale differences.

Image courtesy of Bogdan Mohora, MS (Austin, Texas).

Examination of the Specimen

Slide preparation depends on the primary lesion in consideration and will be discussed in greater detail in the following sections. Once the slide is prepared, place it on the microscope stage and adjust the condenser and light source for optimal visualization. Scan the specimen in a gridlike fashion on low power (usually ×10) and then inspect suspicious findings on higher power (×40 or higher).

Dermatomycoses

Fungal infections of the skin can present as annular papulosquamous lesions, follicular pustules or papules, bullous lesions, hypopigmented patches, and mucosal exudate or erosions, among other manifestations.⁵ Potassium hydroxide (KOH) is the classic medium used in preparation of lesions being assessed for evidence of fungus because it leads to lysis of keratinocytes for better visualization of fungal hyphae and spores. Other media that contain KOH and additional substrates such as dimethyl sulfoxide or chlorazol black E can be used to better highlight fungal elements.⁶

Dermatophytosis
Dermatophytes lead to superficial infection of the epidermis and epidermal appendages and present in a variety of ways, including site-specific infections manifesting typically as erythematous, annular or arcuate scaling (eg, tinea faciei, tinea corporis, tinea cruris, tinea manus, tinea pedis), alopecia with broken hair shafts, black dots, boggy nodules and/or scaling of the scalp (eg, tinea capitis, favus, kerion), and dystrophic nails (eg, onychomycosis).^5,7 For examination of lesional skin scrapings, one can either use clear cellophane tape against the skin to remove scale, which is especially useful in the case of pediatric patients, and then press the tape against a slide prepared with several drops of a KOH-based medium to directly visualize without a coverslip, or scrape the lesion with a No. 15 blade and place the scales onto the glass slide, with further preparation as described below.⁸ For assessment of alopecia or dystrophic nails, scrape lesional skin with a No. 15 blade to obtain affected hair follicles and proximal subungual debris, respectively.^6,9

Once the cellular debris has been obtained and placed on the slide, a coverslip can be overlaid and KOH applied laterally to be taken up across the slide by capillary action. Allow the slide to sit for at least 5 minutes before analyzing to better visualize fungal elements. Both tinea and onychomycosis will show branching septate hyphae extending across keratinocytes; a common false-positive is identifying overlapping keratinocyte edges, which are a similar size, but they can be distinguished from fungi because they do not cross multiple keratinocytes.^1,8 Tinea capitis may demonstrate similar findings or may reveal hair shafts with spores contained within or surrounding it, corresponding to endothrix or ectothrix infection, respectively.⁵

Pityriasis Versicolor and Malassezia Folliculitis
Pityriasis versicolor presents with hypopigmented to pink, finely scaling ovoid papules, usually on the upper back, shoulders, and neck, and is caused by Malassezia furfur and other Malassezia species.⁵ Malassezia folliculitis also is caused by this fungus and presents with monomorphic follicular papules and pustules. Scrapings from the scaly papules will demonstrate keratinocytes with the classic “spaghetti and meatballs” fungal elements, whereas Malassezia folliculitis demonstrates only spores.^5,7

Candidiasis
One possible outpatient presentation of candidiasis is oral thrush, which can exhibit white mucosal exudate or erythematous patches. A tongue blade can be used to scrape the tongue or cheek wall, with subsequent preparatory steps with application of KOH as described for dermatophytes. Cutaneous candidiasis most often develops in intertriginous regions and will exhibit erosive painful lesions with satellite pustules. In both cases, analysis of the specimen will show shorter fatter hyphal elements than seen in dermatophytosis, with pseudohyphae, blunted ends, and potentially yeast forms.⁵

Vesiculobullous Lesions

The Tzanck smear has been used since the 1940s to differentiate between etiologies of blistering disorders and is now most commonly used for the quick identification of herpetic lesions.¹ The test is performed by scraping the base of a deroofed vesicle, pustule, or bulla, and smearing the cellular materials onto a glass slide. The most commonly utilized media for staining in the outpatient setting at my institution (University of Texas Dell Medical School, Austin) is Giemsa, which is composed of azure II–eosin, glycerin, and methanol. It stains nuclei a reddish blue to pink and the cytoplasm blue.¹⁰ After being applied to the slide, the cells are allowed to air-dry for 5 to 10 minutes, and Giemsa stain is subsequently applied and allowed to incubate for 15 minutes, then rinsed carefully with water and directly examined.

Other stains that can be used to perform the Tzanck smear include commercial preparations that may be more accessible in the inpatient settings such as the Wright-Giemsa, Quik-Dip, and Diff-Quick.^1,10

Examination of a Tzanck smear from a herpetic lesion will yield acantholytic, enlarged keratinocytes up to twice their usual size (referred to as ballooning degeneration), and multinucleation. In addition, molding of the nuclei to each other within the multinucleated cells and margination of the nuclear chromatin may be appreciated (Figure 2). Intranuclear inclusion bodies, also known as Cowdry type A bodies, can be seen that are nearly the size of red blood cells but are rare to find, with only 10% of specimens exhibiting this finding in a prospective review of 299 patients with herpetic vesiculobullous lesions.¹¹ Evaluation of the contents of blisters caused by bullous pemphigoid and erythema toxicum neonatorum may yield high densities of eosinophils with normal keratinocyte morphology (Figure 3). Other blistering eruptions such as pemphigus vulgaris and bullous drug eruptions also have characteristic findings.^1,2

Image courtesy of Aron Gewirtzman, MD (Austin, Texas).

Image courtesy of Rachel McAndrew, MD (Austin, Texas).

Gout Preparation

Gout is a systemic disease caused by uric acid accumulation that can present with joint pain and white to red nodules on digits, joints, and ears (known as tophi). Material may be expressed from tophi and examined immediately by polarized light microscopy to confirm the diagnosis.⁵ Specimens will demonstrate needle-shaped, negatively birefringent monosodium urate crystals on polarized light microscopy (Figure 4). An ordinary light microscope can be converted for such use with the lenses of inexpensive polarized sunglasses, placing one lens between the light source and specimen and the other lens between the examiner’s eye and the specimen.¹²

Image courtesy of Paul Massey, MD (Boston, Massachusetts).

Parasitic Infections

Two common parasitic infections identified in outpatient dermatology clinics are scabies mites and Demodex mites. Human scabies is extremely pruritic and caused by infestation with Sarcoptes scabiei var hominis; the typical presentation in an adult is erythematous and crusted papules, linear burrows, and vesiculopustules, especially of the interdigital spaces, wrists, axillae, umbilicus, and genital region.^1,13 Demodicidosis presents with papules and pustules on the face, usually in a patient with background rosacea and diffuse erythema.^1,5,14

If either of these conditions are suspected, mineral oil should be used to prepare the slide because it will maintain viability of the organisms, which are visualized better in motion. Adult scabies mites are roughly 10 times larger than keratinocytes, measuring approximately 250 to 450 µm in length with 8 legs.¹³ Eggs also may be visualized within the cellular debris and typically are 100 to 150 µm in size and ovoid in shape. Of note, polariscopic examination may be a useful adjunct for evaluation of scabies because scabetic spines and scybala (or fecal material) are polarizable.¹⁵

Two types of Demodex mites typically are found in the skin: Demodex folliculorum, which are similarly sized to scabies mites with a more oblong body and occur most commonly in mature hair follicles (eg, eyelashes), and Demodex brevis, which are about half the size (150–200 µm) and live in the sebaceous glands of vellus hairs (Figure 5).¹⁴ Both of these mites have 8 legs, similar to the scabies mite.

Image courtesy of Candelario Antonio Rodriguez Vivian, MD (Monterrey, Mexico).

Hair Preparations

Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.³ One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.¹⁶ Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.⁴

Final Thoughts

Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.

Dermatologists are uniquely equipped amongst clinicians to make bedside diagnoses because of the focus on histopathology and microscopy inherent in our training. This skill is highly valuable in both an inpatient and outpatient setting because it may lead to a rapid diagnosis or be a useful adjunct in the initial clinical decision-making process. Although expert microscopists may be able to garner relevant information from scraping almost any type of lesion, bedside microscopy primarily is used by dermatologists in the United States for consideration of infectious etiologies of a variety of cutaneous manifestations.^1,2

Basic Principles

Lesions that should be considered for bedside microscopic analysis in outpatient settings are scaly lesions, vesiculobullous lesions, inflammatory papules, and pustules¹; microscopic evaluation also can be useful for myriad trichoscopic considerations.^3,4 In some instances, direct visualization of the pathogen is possible (eg, cutaneous fungal infections, demodicidosis, scabetic infections), and in other circumstances reactive changes of keratinocytes or the presence of specific cell types can aid in diagnosis (eg, ballooning degeneration and multinucleation of keratinocytes in herpetic lesions, an abundance of eosinophils in erythema toxicum neonatorum). Different types of media are used to best prepare tissue based on the suspected etiology of the condition.

One major stumbling block for residents when beginning to perform bedside testing is the lack of dimensional understanding of the structures they are searching for; for example, medical students and residents often may mistake fibers for dermatophytes, which typically are much larger than fungal hyphae. Familiarizing oneself with the basic dimensions of different cell types or pathogens in relation to each other (Table) will help further refine the beginner’s ability to effectively search for and identify pathogenic features. This concept is further schematized in Figure 1 to help visualize scale differences.

Image courtesy of Bogdan Mohora, MS (Austin, Texas).

Examination of the Specimen

Slide preparation depends on the primary lesion in consideration and will be discussed in greater detail in the following sections. Once the slide is prepared, place it on the microscope stage and adjust the condenser and light source for optimal visualization. Scan the specimen in a gridlike fashion on low power (usually ×10) and then inspect suspicious findings on higher power (×40 or higher).

Dermatomycoses

Fungal infections of the skin can present as annular papulosquamous lesions, follicular pustules or papules, bullous lesions, hypopigmented patches, and mucosal exudate or erosions, among other manifestations.⁵ Potassium hydroxide (KOH) is the classic medium used in preparation of lesions being assessed for evidence of fungus because it leads to lysis of keratinocytes for better visualization of fungal hyphae and spores. Other media that contain KOH and additional substrates such as dimethyl sulfoxide or chlorazol black E can be used to better highlight fungal elements.⁶

Dermatophytosis
Dermatophytes lead to superficial infection of the epidermis and epidermal appendages and present in a variety of ways, including site-specific infections manifesting typically as erythematous, annular or arcuate scaling (eg, tinea faciei, tinea corporis, tinea cruris, tinea manus, tinea pedis), alopecia with broken hair shafts, black dots, boggy nodules and/or scaling of the scalp (eg, tinea capitis, favus, kerion), and dystrophic nails (eg, onychomycosis).^5,7 For examination of lesional skin scrapings, one can either use clear cellophane tape against the skin to remove scale, which is especially useful in the case of pediatric patients, and then press the tape against a slide prepared with several drops of a KOH-based medium to directly visualize without a coverslip, or scrape the lesion with a No. 15 blade and place the scales onto the glass slide, with further preparation as described below.⁸ For assessment of alopecia or dystrophic nails, scrape lesional skin with a No. 15 blade to obtain affected hair follicles and proximal subungual debris, respectively.^6,9

Once the cellular debris has been obtained and placed on the slide, a coverslip can be overlaid and KOH applied laterally to be taken up across the slide by capillary action. Allow the slide to sit for at least 5 minutes before analyzing to better visualize fungal elements. Both tinea and onychomycosis will show branching septate hyphae extending across keratinocytes; a common false-positive is identifying overlapping keratinocyte edges, which are a similar size, but they can be distinguished from fungi because they do not cross multiple keratinocytes.^1,8 Tinea capitis may demonstrate similar findings or may reveal hair shafts with spores contained within or surrounding it, corresponding to endothrix or ectothrix infection, respectively.⁵

Pityriasis Versicolor and Malassezia Folliculitis
Pityriasis versicolor presents with hypopigmented to pink, finely scaling ovoid papules, usually on the upper back, shoulders, and neck, and is caused by Malassezia furfur and other Malassezia species.⁵ Malassezia folliculitis also is caused by this fungus and presents with monomorphic follicular papules and pustules. Scrapings from the scaly papules will demonstrate keratinocytes with the classic “spaghetti and meatballs” fungal elements, whereas Malassezia folliculitis demonstrates only spores.^5,7

Candidiasis
One possible outpatient presentation of candidiasis is oral thrush, which can exhibit white mucosal exudate or erythematous patches. A tongue blade can be used to scrape the tongue or cheek wall, with subsequent preparatory steps with application of KOH as described for dermatophytes. Cutaneous candidiasis most often develops in intertriginous regions and will exhibit erosive painful lesions with satellite pustules. In both cases, analysis of the specimen will show shorter fatter hyphal elements than seen in dermatophytosis, with pseudohyphae, blunted ends, and potentially yeast forms.⁵

Vesiculobullous Lesions

The Tzanck smear has been used since the 1940s to differentiate between etiologies of blistering disorders and is now most commonly used for the quick identification of herpetic lesions.¹ The test is performed by scraping the base of a deroofed vesicle, pustule, or bulla, and smearing the cellular materials onto a glass slide. The most commonly utilized media for staining in the outpatient setting at my institution (University of Texas Dell Medical School, Austin) is Giemsa, which is composed of azure II–eosin, glycerin, and methanol. It stains nuclei a reddish blue to pink and the cytoplasm blue.¹⁰ After being applied to the slide, the cells are allowed to air-dry for 5 to 10 minutes, and Giemsa stain is subsequently applied and allowed to incubate for 15 minutes, then rinsed carefully with water and directly examined.

Other stains that can be used to perform the Tzanck smear include commercial preparations that may be more accessible in the inpatient settings such as the Wright-Giemsa, Quik-Dip, and Diff-Quick.^1,10

Examination of a Tzanck smear from a herpetic lesion will yield acantholytic, enlarged keratinocytes up to twice their usual size (referred to as ballooning degeneration), and multinucleation. In addition, molding of the nuclei to each other within the multinucleated cells and margination of the nuclear chromatin may be appreciated (Figure 2). Intranuclear inclusion bodies, also known as Cowdry type A bodies, can be seen that are nearly the size of red blood cells but are rare to find, with only 10% of specimens exhibiting this finding in a prospective review of 299 patients with herpetic vesiculobullous lesions.¹¹ Evaluation of the contents of blisters caused by bullous pemphigoid and erythema toxicum neonatorum may yield high densities of eosinophils with normal keratinocyte morphology (Figure 3). Other blistering eruptions such as pemphigus vulgaris and bullous drug eruptions also have characteristic findings.^1,2

Image courtesy of Aron Gewirtzman, MD (Austin, Texas).

Image courtesy of Rachel McAndrew, MD (Austin, Texas).

Gout Preparation

Gout is a systemic disease caused by uric acid accumulation that can present with joint pain and white to red nodules on digits, joints, and ears (known as tophi). Material may be expressed from tophi and examined immediately by polarized light microscopy to confirm the diagnosis.⁵ Specimens will demonstrate needle-shaped, negatively birefringent monosodium urate crystals on polarized light microscopy (Figure 4). An ordinary light microscope can be converted for such use with the lenses of inexpensive polarized sunglasses, placing one lens between the light source and specimen and the other lens between the examiner’s eye and the specimen.¹²

Image courtesy of Paul Massey, MD (Boston, Massachusetts).

Parasitic Infections

Two common parasitic infections identified in outpatient dermatology clinics are scabies mites and Demodex mites. Human scabies is extremely pruritic and caused by infestation with Sarcoptes scabiei var hominis; the typical presentation in an adult is erythematous and crusted papules, linear burrows, and vesiculopustules, especially of the interdigital spaces, wrists, axillae, umbilicus, and genital region.^1,13 Demodicidosis presents with papules and pustules on the face, usually in a patient with background rosacea and diffuse erythema.^1,5,14

If either of these conditions are suspected, mineral oil should be used to prepare the slide because it will maintain viability of the organisms, which are visualized better in motion. Adult scabies mites are roughly 10 times larger than keratinocytes, measuring approximately 250 to 450 µm in length with 8 legs.¹³ Eggs also may be visualized within the cellular debris and typically are 100 to 150 µm in size and ovoid in shape. Of note, polariscopic examination may be a useful adjunct for evaluation of scabies because scabetic spines and scybala (or fecal material) are polarizable.¹⁵

Two types of Demodex mites typically are found in the skin: Demodex folliculorum, which are similarly sized to scabies mites with a more oblong body and occur most commonly in mature hair follicles (eg, eyelashes), and Demodex brevis, which are about half the size (150–200 µm) and live in the sebaceous glands of vellus hairs (Figure 5).¹⁴ Both of these mites have 8 legs, similar to the scabies mite.

Image courtesy of Candelario Antonio Rodriguez Vivian, MD (Monterrey, Mexico).

Hair Preparations

Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.³ One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.¹⁶ Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.⁴

Final Thoughts

Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.

Dermatologists are uniquely equipped amongst clinicians to make bedside diagnoses because of the focus on histopathology and microscopy inherent in our training. This skill is highly valuable in both an inpatient and outpatient setting because it may lead to a rapid diagnosis or be a useful adjunct in the initial clinical decision-making process. Although expert microscopists may be able to garner relevant information from scraping almost any type of lesion, bedside microscopy primarily is used by dermatologists in the United States for consideration of infectious etiologies of a variety of cutaneous manifestations.^1,2

Basic Principles

Lesions that should be considered for bedside microscopic analysis in outpatient settings are scaly lesions, vesiculobullous lesions, inflammatory papules, and pustules¹; microscopic evaluation also can be useful for myriad trichoscopic considerations.^3,4 In some instances, direct visualization of the pathogen is possible (eg, cutaneous fungal infections, demodicidosis, scabetic infections), and in other circumstances reactive changes of keratinocytes or the presence of specific cell types can aid in diagnosis (eg, ballooning degeneration and multinucleation of keratinocytes in herpetic lesions, an abundance of eosinophils in erythema toxicum neonatorum). Different types of media are used to best prepare tissue based on the suspected etiology of the condition.

One major stumbling block for residents when beginning to perform bedside testing is the lack of dimensional understanding of the structures they are searching for; for example, medical students and residents often may mistake fibers for dermatophytes, which typically are much larger than fungal hyphae. Familiarizing oneself with the basic dimensions of different cell types or pathogens in relation to each other (Table) will help further refine the beginner’s ability to effectively search for and identify pathogenic features. This concept is further schematized in Figure 1 to help visualize scale differences.

Image courtesy of Bogdan Mohora, MS (Austin, Texas).

Examination of the Specimen

Slide preparation depends on the primary lesion in consideration and will be discussed in greater detail in the following sections. Once the slide is prepared, place it on the microscope stage and adjust the condenser and light source for optimal visualization. Scan the specimen in a gridlike fashion on low power (usually ×10) and then inspect suspicious findings on higher power (×40 or higher).

Dermatomycoses

Fungal infections of the skin can present as annular papulosquamous lesions, follicular pustules or papules, bullous lesions, hypopigmented patches, and mucosal exudate or erosions, among other manifestations.⁵ Potassium hydroxide (KOH) is the classic medium used in preparation of lesions being assessed for evidence of fungus because it leads to lysis of keratinocytes for better visualization of fungal hyphae and spores. Other media that contain KOH and additional substrates such as dimethyl sulfoxide or chlorazol black E can be used to better highlight fungal elements.⁶

Dermatophytosis
Dermatophytes lead to superficial infection of the epidermis and epidermal appendages and present in a variety of ways, including site-specific infections manifesting typically as erythematous, annular or arcuate scaling (eg, tinea faciei, tinea corporis, tinea cruris, tinea manus, tinea pedis), alopecia with broken hair shafts, black dots, boggy nodules and/or scaling of the scalp (eg, tinea capitis, favus, kerion), and dystrophic nails (eg, onychomycosis).^5,7 For examination of lesional skin scrapings, one can either use clear cellophane tape against the skin to remove scale, which is especially useful in the case of pediatric patients, and then press the tape against a slide prepared with several drops of a KOH-based medium to directly visualize without a coverslip, or scrape the lesion with a No. 15 blade and place the scales onto the glass slide, with further preparation as described below.⁸ For assessment of alopecia or dystrophic nails, scrape lesional skin with a No. 15 blade to obtain affected hair follicles and proximal subungual debris, respectively.^6,9

Once the cellular debris has been obtained and placed on the slide, a coverslip can be overlaid and KOH applied laterally to be taken up across the slide by capillary action. Allow the slide to sit for at least 5 minutes before analyzing to better visualize fungal elements. Both tinea and onychomycosis will show branching septate hyphae extending across keratinocytes; a common false-positive is identifying overlapping keratinocyte edges, which are a similar size, but they can be distinguished from fungi because they do not cross multiple keratinocytes.^1,8 Tinea capitis may demonstrate similar findings or may reveal hair shafts with spores contained within or surrounding it, corresponding to endothrix or ectothrix infection, respectively.⁵

Pityriasis Versicolor and Malassezia Folliculitis
Pityriasis versicolor presents with hypopigmented to pink, finely scaling ovoid papules, usually on the upper back, shoulders, and neck, and is caused by Malassezia furfur and other Malassezia species.⁵ Malassezia folliculitis also is caused by this fungus and presents with monomorphic follicular papules and pustules. Scrapings from the scaly papules will demonstrate keratinocytes with the classic “spaghetti and meatballs” fungal elements, whereas Malassezia folliculitis demonstrates only spores.^5,7

Candidiasis
One possible outpatient presentation of candidiasis is oral thrush, which can exhibit white mucosal exudate or erythematous patches. A tongue blade can be used to scrape the tongue or cheek wall, with subsequent preparatory steps with application of KOH as described for dermatophytes. Cutaneous candidiasis most often develops in intertriginous regions and will exhibit erosive painful lesions with satellite pustules. In both cases, analysis of the specimen will show shorter fatter hyphal elements than seen in dermatophytosis, with pseudohyphae, blunted ends, and potentially yeast forms.⁵

Vesiculobullous Lesions

The Tzanck smear has been used since the 1940s to differentiate between etiologies of blistering disorders and is now most commonly used for the quick identification of herpetic lesions.¹ The test is performed by scraping the base of a deroofed vesicle, pustule, or bulla, and smearing the cellular materials onto a glass slide. The most commonly utilized media for staining in the outpatient setting at my institution (University of Texas Dell Medical School, Austin) is Giemsa, which is composed of azure II–eosin, glycerin, and methanol. It stains nuclei a reddish blue to pink and the cytoplasm blue.¹⁰ After being applied to the slide, the cells are allowed to air-dry for 5 to 10 minutes, and Giemsa stain is subsequently applied and allowed to incubate for 15 minutes, then rinsed carefully with water and directly examined.

Other stains that can be used to perform the Tzanck smear include commercial preparations that may be more accessible in the inpatient settings such as the Wright-Giemsa, Quik-Dip, and Diff-Quick.^1,10

Examination of a Tzanck smear from a herpetic lesion will yield acantholytic, enlarged keratinocytes up to twice their usual size (referred to as ballooning degeneration), and multinucleation. In addition, molding of the nuclei to each other within the multinucleated cells and margination of the nuclear chromatin may be appreciated (Figure 2). Intranuclear inclusion bodies, also known as Cowdry type A bodies, can be seen that are nearly the size of red blood cells but are rare to find, with only 10% of specimens exhibiting this finding in a prospective review of 299 patients with herpetic vesiculobullous lesions.¹¹ Evaluation of the contents of blisters caused by bullous pemphigoid and erythema toxicum neonatorum may yield high densities of eosinophils with normal keratinocyte morphology (Figure 3). Other blistering eruptions such as pemphigus vulgaris and bullous drug eruptions also have characteristic findings.^1,2

Image courtesy of Aron Gewirtzman, MD (Austin, Texas).

Image courtesy of Rachel McAndrew, MD (Austin, Texas).

Gout Preparation

Gout is a systemic disease caused by uric acid accumulation that can present with joint pain and white to red nodules on digits, joints, and ears (known as tophi). Material may be expressed from tophi and examined immediately by polarized light microscopy to confirm the diagnosis.⁵ Specimens will demonstrate needle-shaped, negatively birefringent monosodium urate crystals on polarized light microscopy (Figure 4). An ordinary light microscope can be converted for such use with the lenses of inexpensive polarized sunglasses, placing one lens between the light source and specimen and the other lens between the examiner’s eye and the specimen.¹²

Image courtesy of Paul Massey, MD (Boston, Massachusetts).

Parasitic Infections

Two common parasitic infections identified in outpatient dermatology clinics are scabies mites and Demodex mites. Human scabies is extremely pruritic and caused by infestation with Sarcoptes scabiei var hominis; the typical presentation in an adult is erythematous and crusted papules, linear burrows, and vesiculopustules, especially of the interdigital spaces, wrists, axillae, umbilicus, and genital region.^1,13 Demodicidosis presents with papules and pustules on the face, usually in a patient with background rosacea and diffuse erythema.^1,5,14

If either of these conditions are suspected, mineral oil should be used to prepare the slide because it will maintain viability of the organisms, which are visualized better in motion. Adult scabies mites are roughly 10 times larger than keratinocytes, measuring approximately 250 to 450 µm in length with 8 legs.¹³ Eggs also may be visualized within the cellular debris and typically are 100 to 150 µm in size and ovoid in shape. Of note, polariscopic examination may be a useful adjunct for evaluation of scabies because scabetic spines and scybala (or fecal material) are polarizable.¹⁵

Two types of Demodex mites typically are found in the skin: Demodex folliculorum, which are similarly sized to scabies mites with a more oblong body and occur most commonly in mature hair follicles (eg, eyelashes), and Demodex brevis, which are about half the size (150–200 µm) and live in the sebaceous glands of vellus hairs (Figure 5).¹⁴ Both of these mites have 8 legs, similar to the scabies mite.

Image courtesy of Candelario Antonio Rodriguez Vivian, MD (Monterrey, Mexico).

Hair Preparations

Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.³ One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.¹⁶ Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.⁴

Final Thoughts

Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.

Dermal fillers are considered Class III medical devices by the US Food and Drug Administration (FDA).¹ Reports of adverse events (AEs) for medical devices are made public by the FDA to allow for transparent postmarketing surveillance.²The AE trends extracted from these historical data may help distinguish between expected learning curves of new dermal fillers versus unsafe products that may require FDA intervention. Considering that aesthetic treatments are not medically necessary, a low risk profile is paramount and determining what constitutes normal learning curves is important for impartial assessment of AEs as new fillers come on the market. The concept of a 3-year learning curve can be an important tool for safety monitoring going forward, creating a bar for quality that could trigger increased surveillance if a product fails to meet an expected arc of diminished AEs over time. This study serves to evaluate historical AE data and to establish learning curves for FDA-approved dermal fillers.

Methods

We searched the OpenFDA Device Adverse Event Report Browser (http://openfda.shinyapps.io/devicereports/) for reported AEs within the FDA product code LMH (Implant, Dermal, For Aesthetic Use) that were received from January 1, 1983, to December 31, 2017. For each reported AE, information related to the date of the reported event and the device brand name were recorded. Devices implicated in each AE were classified based on primary composition according to the following 5 categories: collagen, hyaluronic acid (HA), hydroxylapatite, poly-L-lactic acid (PLLA), and polymethyl methacrylate (PMMA). Inaccurate entries of reported AEs or those intended for nonaesthetic use were excluded from the study. A total of 8530 AEs were included in the study. To normalize the data, we obtained annual reports for the number of procedures performed by filler type from the American Society of Plastic Surgeons (ASPS) cosmetic procedure trends. ³ We calculated the annual AE rates for each approved filler by dividing the number of AEs by the number of procedures performed that year.

Results

The trends of different filler types depicting the number of procedures performed over time are shown in Figure 1. Data from the ASPS dated back to 2005; therefore, the number of procedures performed prior to that were extrapolated with knowledge of products’ approval dates and market share, indicated by a dotted line. To determine AE rates for each year, we divided the number of AEs by the number of reported procedures for each filler type. The AE rates are displayed graphically in Figures 2 and 3 with superimposed FDA approval dates for each filler.⁴

Two major peaks in reported AE rates for all fillers were noted in the late 1990s and late 2000s, mostly associated with collagen and PLLA fillers, respectively (Figure 2). Overall, there has been a low rate of AEs associated with HA fillers since their initial approval in the early 2000s.

Comment

Our study is unique in that it analyzes reported AE data over a 34-year period for injectable dermal fillers. To our knowledge, this novel method of calculating AE rates across dermal fillers and for individual products is the first of its kind that facilitates usage-normalized comparison of different filler types.

All OpenFDA data are self-reported and therefore have inherent limitations. Anyone can enter information on AEs in this system, including both patients and health care providers, so the quality of the input may be variable. However, this output is the only representation we have for nearly 35 years of AE history for this burgeoning category of popular aesthetic treatments. Another study limitation is that not everyone may know that reporting an AE in the OpenFDA is an option; therefore, we may be missing a portion of AEs due to underreporting. Underreporting may be especially at play in the years before the Internet was prevalent for residential use since access to the Internet would be required to report an AR on the website. However, examining the available data provides an important window into valuable information on complications that have occurred and have been reported for FDA-approved dermal fillers.

An additional challenge in constructing this study was assessing the total number of injectable dermal filler treatments being performed annually across filler types for normalization of the data. Although the absolute numbers of filler use as captured by the ASPS are smaller than the true total filler use across all injectors, the relative use of different filler products will be similar across all specialties because it reflects product popularity. Annual surveys on aesthetic procedures also are conducted by the American Society for Dermatologic Surgery and the American Association for Facial Plastic and Reconstructive Surgery, but neither one captures the relative usage of different filler types. Because individual filler companies do not publish their annual sales numbers by product, the ASPS data give us the best gauge of relative use of fillers by product type given the available information. We conclude that the comparison of AE rates would remain the same even if we had data for total annual filler use across specialties.

Our graphical depiction of the data clearly demonstrates the low AE profile of HA fillers, which is in line with the general consensus of their safety that has contributed to their vast popularity; however, this study represents the first time usage-normalized AE rates are compared to other filler compositions. Hyaluronic acid fillers have the unique feature of being able to be dissolved with the hyaluronidase enzyme, which can limit adverse event potential as compared to other ingredient classes of filler types and may be reflected in their low overall AE profile. The AE rate spike and resolution for collagen fillers represent what we refer to as a “normal learning curve” based on our analysis of the data set as a whole, suggesting an appropriate time course of increased familiarity with the product without inherent issues with the product itself. Multiple sequential anatomic site indications were approved for hydroxylapatite fillers from 2006 through 2015, which may have yielded overlapping learning curves for each approval, resulting in a rather uniform AE rate. The early drop-off in AE rates after the 2015 anatomic site approval may represent the beginning of a normal learning curve, and continued surveillance of AE rates would be of value to confirm this trend. We saw a similar 3-year learning curve for PLLA fillers as the curve for collagen fillers, suggesting a normal learning curve and no out-of-line safety issues. Polymethylmethacrylate fillers were approved in 2006 and were taken off the market for a period in the late 2000s, explaining the drop-off. Once they were back on the market, we do not see a typical learning curve for PMMA, which may warrant surveillance for safety by both clinicians and the FDA.

Conclusion

Our study represents a novel method of evaluating the safety of medical devices, specifically aesthetic fillers. We showed that every AE rate curve for different filler types tells a story. Reactions to AEs for new fillers should be placed in the context of whether they seem to be following the established learning curve.

Dermal fillers are considered Class III medical devices by the US Food and Drug Administration (FDA).¹ Reports of adverse events (AEs) for medical devices are made public by the FDA to allow for transparent postmarketing surveillance.²The AE trends extracted from these historical data may help distinguish between expected learning curves of new dermal fillers versus unsafe products that may require FDA intervention. Considering that aesthetic treatments are not medically necessary, a low risk profile is paramount and determining what constitutes normal learning curves is important for impartial assessment of AEs as new fillers come on the market. The concept of a 3-year learning curve can be an important tool for safety monitoring going forward, creating a bar for quality that could trigger increased surveillance if a product fails to meet an expected arc of diminished AEs over time. This study serves to evaluate historical AE data and to establish learning curves for FDA-approved dermal fillers.

Methods

We searched the OpenFDA Device Adverse Event Report Browser (http://openfda.shinyapps.io/devicereports/) for reported AEs within the FDA product code LMH (Implant, Dermal, For Aesthetic Use) that were received from January 1, 1983, to December 31, 2017. For each reported AE, information related to the date of the reported event and the device brand name were recorded. Devices implicated in each AE were classified based on primary composition according to the following 5 categories: collagen, hyaluronic acid (HA), hydroxylapatite, poly-L-lactic acid (PLLA), and polymethyl methacrylate (PMMA). Inaccurate entries of reported AEs or those intended for nonaesthetic use were excluded from the study. A total of 8530 AEs were included in the study. To normalize the data, we obtained annual reports for the number of procedures performed by filler type from the American Society of Plastic Surgeons (ASPS) cosmetic procedure trends. ³ We calculated the annual AE rates for each approved filler by dividing the number of AEs by the number of procedures performed that year.

Results

The trends of different filler types depicting the number of procedures performed over time are shown in Figure 1. Data from the ASPS dated back to 2005; therefore, the number of procedures performed prior to that were extrapolated with knowledge of products’ approval dates and market share, indicated by a dotted line. To determine AE rates for each year, we divided the number of AEs by the number of reported procedures for each filler type. The AE rates are displayed graphically in Figures 2 and 3 with superimposed FDA approval dates for each filler.⁴

Two major peaks in reported AE rates for all fillers were noted in the late 1990s and late 2000s, mostly associated with collagen and PLLA fillers, respectively (Figure 2). Overall, there has been a low rate of AEs associated with HA fillers since their initial approval in the early 2000s.

Comment

Our study is unique in that it analyzes reported AE data over a 34-year period for injectable dermal fillers. To our knowledge, this novel method of calculating AE rates across dermal fillers and for individual products is the first of its kind that facilitates usage-normalized comparison of different filler types.

All OpenFDA data are self-reported and therefore have inherent limitations. Anyone can enter information on AEs in this system, including both patients and health care providers, so the quality of the input may be variable. However, this output is the only representation we have for nearly 35 years of AE history for this burgeoning category of popular aesthetic treatments. Another study limitation is that not everyone may know that reporting an AE in the OpenFDA is an option; therefore, we may be missing a portion of AEs due to underreporting. Underreporting may be especially at play in the years before the Internet was prevalent for residential use since access to the Internet would be required to report an AR on the website. However, examining the available data provides an important window into valuable information on complications that have occurred and have been reported for FDA-approved dermal fillers.

An additional challenge in constructing this study was assessing the total number of injectable dermal filler treatments being performed annually across filler types for normalization of the data. Although the absolute numbers of filler use as captured by the ASPS are smaller than the true total filler use across all injectors, the relative use of different filler products will be similar across all specialties because it reflects product popularity. Annual surveys on aesthetic procedures also are conducted by the American Society for Dermatologic Surgery and the American Association for Facial Plastic and Reconstructive Surgery, but neither one captures the relative usage of different filler types. Because individual filler companies do not publish their annual sales numbers by product, the ASPS data give us the best gauge of relative use of fillers by product type given the available information. We conclude that the comparison of AE rates would remain the same even if we had data for total annual filler use across specialties.

Our graphical depiction of the data clearly demonstrates the low AE profile of HA fillers, which is in line with the general consensus of their safety that has contributed to their vast popularity; however, this study represents the first time usage-normalized AE rates are compared to other filler compositions. Hyaluronic acid fillers have the unique feature of being able to be dissolved with the hyaluronidase enzyme, which can limit adverse event potential as compared to other ingredient classes of filler types and may be reflected in their low overall AE profile. The AE rate spike and resolution for collagen fillers represent what we refer to as a “normal learning curve” based on our analysis of the data set as a whole, suggesting an appropriate time course of increased familiarity with the product without inherent issues with the product itself. Multiple sequential anatomic site indications were approved for hydroxylapatite fillers from 2006 through 2015, which may have yielded overlapping learning curves for each approval, resulting in a rather uniform AE rate. The early drop-off in AE rates after the 2015 anatomic site approval may represent the beginning of a normal learning curve, and continued surveillance of AE rates would be of value to confirm this trend. We saw a similar 3-year learning curve for PLLA fillers as the curve for collagen fillers, suggesting a normal learning curve and no out-of-line safety issues. Polymethylmethacrylate fillers were approved in 2006 and were taken off the market for a period in the late 2000s, explaining the drop-off. Once they were back on the market, we do not see a typical learning curve for PMMA, which may warrant surveillance for safety by both clinicians and the FDA.

Conclusion

Our study represents a novel method of evaluating the safety of medical devices, specifically aesthetic fillers. We showed that every AE rate curve for different filler types tells a story. Reactions to AEs for new fillers should be placed in the context of whether they seem to be following the established learning curve.

Dermal fillers are considered Class III medical devices by the US Food and Drug Administration (FDA).¹ Reports of adverse events (AEs) for medical devices are made public by the FDA to allow for transparent postmarketing surveillance.²The AE trends extracted from these historical data may help distinguish between expected learning curves of new dermal fillers versus unsafe products that may require FDA intervention. Considering that aesthetic treatments are not medically necessary, a low risk profile is paramount and determining what constitutes normal learning curves is important for impartial assessment of AEs as new fillers come on the market. The concept of a 3-year learning curve can be an important tool for safety monitoring going forward, creating a bar for quality that could trigger increased surveillance if a product fails to meet an expected arc of diminished AEs over time. This study serves to evaluate historical AE data and to establish learning curves for FDA-approved dermal fillers.

Methods

We searched the OpenFDA Device Adverse Event Report Browser (http://openfda.shinyapps.io/devicereports/) for reported AEs within the FDA product code LMH (Implant, Dermal, For Aesthetic Use) that were received from January 1, 1983, to December 31, 2017. For each reported AE, information related to the date of the reported event and the device brand name were recorded. Devices implicated in each AE were classified based on primary composition according to the following 5 categories: collagen, hyaluronic acid (HA), hydroxylapatite, poly-L-lactic acid (PLLA), and polymethyl methacrylate (PMMA). Inaccurate entries of reported AEs or those intended for nonaesthetic use were excluded from the study. A total of 8530 AEs were included in the study. To normalize the data, we obtained annual reports for the number of procedures performed by filler type from the American Society of Plastic Surgeons (ASPS) cosmetic procedure trends. ³ We calculated the annual AE rates for each approved filler by dividing the number of AEs by the number of procedures performed that year.

Results

The trends of different filler types depicting the number of procedures performed over time are shown in Figure 1. Data from the ASPS dated back to 2005; therefore, the number of procedures performed prior to that were extrapolated with knowledge of products’ approval dates and market share, indicated by a dotted line. To determine AE rates for each year, we divided the number of AEs by the number of reported procedures for each filler type. The AE rates are displayed graphically in Figures 2 and 3 with superimposed FDA approval dates for each filler.⁴

Two major peaks in reported AE rates for all fillers were noted in the late 1990s and late 2000s, mostly associated with collagen and PLLA fillers, respectively (Figure 2). Overall, there has been a low rate of AEs associated with HA fillers since their initial approval in the early 2000s.

Comment

Our study is unique in that it analyzes reported AE data over a 34-year period for injectable dermal fillers. To our knowledge, this novel method of calculating AE rates across dermal fillers and for individual products is the first of its kind that facilitates usage-normalized comparison of different filler types.

All OpenFDA data are self-reported and therefore have inherent limitations. Anyone can enter information on AEs in this system, including both patients and health care providers, so the quality of the input may be variable. However, this output is the only representation we have for nearly 35 years of AE history for this burgeoning category of popular aesthetic treatments. Another study limitation is that not everyone may know that reporting an AE in the OpenFDA is an option; therefore, we may be missing a portion of AEs due to underreporting. Underreporting may be especially at play in the years before the Internet was prevalent for residential use since access to the Internet would be required to report an AR on the website. However, examining the available data provides an important window into valuable information on complications that have occurred and have been reported for FDA-approved dermal fillers.

An additional challenge in constructing this study was assessing the total number of injectable dermal filler treatments being performed annually across filler types for normalization of the data. Although the absolute numbers of filler use as captured by the ASPS are smaller than the true total filler use across all injectors, the relative use of different filler products will be similar across all specialties because it reflects product popularity. Annual surveys on aesthetic procedures also are conducted by the American Society for Dermatologic Surgery and the American Association for Facial Plastic and Reconstructive Surgery, but neither one captures the relative usage of different filler types. Because individual filler companies do not publish their annual sales numbers by product, the ASPS data give us the best gauge of relative use of fillers by product type given the available information. We conclude that the comparison of AE rates would remain the same even if we had data for total annual filler use across specialties.

Our graphical depiction of the data clearly demonstrates the low AE profile of HA fillers, which is in line with the general consensus of their safety that has contributed to their vast popularity; however, this study represents the first time usage-normalized AE rates are compared to other filler compositions. Hyaluronic acid fillers have the unique feature of being able to be dissolved with the hyaluronidase enzyme, which can limit adverse event potential as compared to other ingredient classes of filler types and may be reflected in their low overall AE profile. The AE rate spike and resolution for collagen fillers represent what we refer to as a “normal learning curve” based on our analysis of the data set as a whole, suggesting an appropriate time course of increased familiarity with the product without inherent issues with the product itself. Multiple sequential anatomic site indications were approved for hydroxylapatite fillers from 2006 through 2015, which may have yielded overlapping learning curves for each approval, resulting in a rather uniform AE rate. The early drop-off in AE rates after the 2015 anatomic site approval may represent the beginning of a normal learning curve, and continued surveillance of AE rates would be of value to confirm this trend. We saw a similar 3-year learning curve for PLLA fillers as the curve for collagen fillers, suggesting a normal learning curve and no out-of-line safety issues. Polymethylmethacrylate fillers were approved in 2006 and were taken off the market for a period in the late 2000s, explaining the drop-off. Once they were back on the market, we do not see a typical learning curve for PMMA, which may warrant surveillance for safety by both clinicians and the FDA.

Conclusion

Our study represents a novel method of evaluating the safety of medical devices, specifically aesthetic fillers. We showed that every AE rate curve for different filler types tells a story. Reactions to AEs for new fillers should be placed in the context of whether they seem to be following the established learning curve.

The Diagnosis: Bowenoid Papulosis 

A 4-mm punch biopsy was performed from the active border of brown plaques on the dorsal penis. Histopathology revealed parakeratotic hyperkeratosis, acanthosis, loss of maturation in epithelium, and full-size atypia (Figure 1). Ki-67 index was 90% positive in the epidermis (Figure 2). Staining for p16 and human papillomavirus (HPV) screening was positive for HPV type 16 (Figure 3). Serologic tests for other sexually transmitted infections were negative. A diagnosis of penile bowenoid papulosis (BP) with grade 3 penile intraepithelial neoplasia was made, and treatment with topical 5-fluorouracil (5-FU) was initiated. Almost total regression was appreciated at 1-month follow-up (Figure 4), and he also was recurrence free at 1-year follow-up.

Penile intraepithelial neoplasia (PIN), or penile squamous cell carcinoma in situ, is a rare disease with high morbidity and mortality rates. Clinically, PIN is comprised of a clinical spectrum including 3 different entities: erythroplasia of Queyrat, Bowen disease, and BP.¹ Histologically, PIN also is classified into 3 subtypes according to histological depth of epidermal atypia.¹

Bowenoid papulosis usually is characterized by multiple red-brown or flesh-colored papules that most commonly appear on the shaft or glans of the penis. Bowenoid papulosis frequently is associated with high-risk types of HPV, such as HPV type 16, and is sometimes difficult to differentiate clinically from pigmented condyloma acuminatum. The clinical lesions of BP usually are less papillomatous, smoother topped, more polymorphic, and more coalescent compared to common genital viral condyloma acuminatum.² Bowenoid papulosis usually is seen in young (<30 years of age) sexually active men, unlike the patches or plaques of erythroplasia of Queyrat or Bowen disease, which are seen in older men aged 45 to 75 years. Bowenoid papulosis also has a lower malignancy potential than erythroplasia of Queyrat and Bowen disease.²

Penile melanosis, penile lentigo, and seborrheic keratosis comprise the differential diagnosis of dark spots on the penis and also should be kept in mind. Penile melanosis is the most common cause of dark spots on the penis. When the dark spots have irregular borders and change in color, they may be misdiagnosed as malignant lesions such as melanoma.³ In most cases, biopsy is indicated. Histologically, penile melanosis is characterized by hyperpigmentation of the basal cell layer with no melanocytic hyperplasia. Treatment is unnecessary in most cases.

Penile lentigo presents as small flat pigmented spots on the penile skin with clearly defined margins surrounded by normal-appearing skin. Histologically, it is characterized by hyperplasia of melanocytes above the basement membrane of the epidermis.³

Penile pigmented seborrheic keratosis is a rare clinical entity that can be easily misinterpreted as condyloma acuminatum. Histologically, it is characterized by basal cell hyperplasia with cystic formation in the thickened epidermis. Excisional biopsy may be the only way to rule out malignant disease.

Treatment options for PIN include cryotherapy, CO₂ or Nd:YAG lasers, photodynamic therapy, topical 5-FU or imiquimod therapy, and surgical excision such as Mohs micrographic surgery.^4-9 Although these therapeutic modalities usually are effective, recurrence is common.⁶ The patients' discomfort and poor cosmetic and functional outcomes from the surgical removal of lesions also present a challenge in treatment planning. 

In our patient, we quickly achieved a good result with topical 5-FU, though the disease was in local advanced stage. It is important for clinicians to consider 5-FU as an effective treatment option for PIN before planning surgery.

The Diagnosis: Bowenoid Papulosis 

A 4-mm punch biopsy was performed from the active border of brown plaques on the dorsal penis. Histopathology revealed parakeratotic hyperkeratosis, acanthosis, loss of maturation in epithelium, and full-size atypia (Figure 1). Ki-67 index was 90% positive in the epidermis (Figure 2). Staining for p16 and human papillomavirus (HPV) screening was positive for HPV type 16 (Figure 3). Serologic tests for other sexually transmitted infections were negative. A diagnosis of penile bowenoid papulosis (BP) with grade 3 penile intraepithelial neoplasia was made, and treatment with topical 5-fluorouracil (5-FU) was initiated. Almost total regression was appreciated at 1-month follow-up (Figure 4), and he also was recurrence free at 1-year follow-up.

Penile intraepithelial neoplasia (PIN), or penile squamous cell carcinoma in situ, is a rare disease with high morbidity and mortality rates. Clinically, PIN is comprised of a clinical spectrum including 3 different entities: erythroplasia of Queyrat, Bowen disease, and BP.¹ Histologically, PIN also is classified into 3 subtypes according to histological depth of epidermal atypia.¹

Bowenoid papulosis usually is characterized by multiple red-brown or flesh-colored papules that most commonly appear on the shaft or glans of the penis. Bowenoid papulosis frequently is associated with high-risk types of HPV, such as HPV type 16, and is sometimes difficult to differentiate clinically from pigmented condyloma acuminatum. The clinical lesions of BP usually are less papillomatous, smoother topped, more polymorphic, and more coalescent compared to common genital viral condyloma acuminatum.² Bowenoid papulosis usually is seen in young (<30 years of age) sexually active men, unlike the patches or plaques of erythroplasia of Queyrat or Bowen disease, which are seen in older men aged 45 to 75 years. Bowenoid papulosis also has a lower malignancy potential than erythroplasia of Queyrat and Bowen disease.²

Penile melanosis, penile lentigo, and seborrheic keratosis comprise the differential diagnosis of dark spots on the penis and also should be kept in mind. Penile melanosis is the most common cause of dark spots on the penis. When the dark spots have irregular borders and change in color, they may be misdiagnosed as malignant lesions such as melanoma.³ In most cases, biopsy is indicated. Histologically, penile melanosis is characterized by hyperpigmentation of the basal cell layer with no melanocytic hyperplasia. Treatment is unnecessary in most cases.

Penile lentigo presents as small flat pigmented spots on the penile skin with clearly defined margins surrounded by normal-appearing skin. Histologically, it is characterized by hyperplasia of melanocytes above the basement membrane of the epidermis.³

Penile pigmented seborrheic keratosis is a rare clinical entity that can be easily misinterpreted as condyloma acuminatum. Histologically, it is characterized by basal cell hyperplasia with cystic formation in the thickened epidermis. Excisional biopsy may be the only way to rule out malignant disease.

Treatment options for PIN include cryotherapy, CO₂ or Nd:YAG lasers, photodynamic therapy, topical 5-FU or imiquimod therapy, and surgical excision such as Mohs micrographic surgery.^4-9 Although these therapeutic modalities usually are effective, recurrence is common.⁶ The patients' discomfort and poor cosmetic and functional outcomes from the surgical removal of lesions also present a challenge in treatment planning. 

In our patient, we quickly achieved a good result with topical 5-FU, though the disease was in local advanced stage. It is important for clinicians to consider 5-FU as an effective treatment option for PIN before planning surgery.

The Diagnosis: Bowenoid Papulosis 

A 4-mm punch biopsy was performed from the active border of brown plaques on the dorsal penis. Histopathology revealed parakeratotic hyperkeratosis, acanthosis, loss of maturation in epithelium, and full-size atypia (Figure 1). Ki-67 index was 90% positive in the epidermis (Figure 2). Staining for p16 and human papillomavirus (HPV) screening was positive for HPV type 16 (Figure 3). Serologic tests for other sexually transmitted infections were negative. A diagnosis of penile bowenoid papulosis (BP) with grade 3 penile intraepithelial neoplasia was made, and treatment with topical 5-fluorouracil (5-FU) was initiated. Almost total regression was appreciated at 1-month follow-up (Figure 4), and he also was recurrence free at 1-year follow-up.

Penile intraepithelial neoplasia (PIN), or penile squamous cell carcinoma in situ, is a rare disease with high morbidity and mortality rates. Clinically, PIN is comprised of a clinical spectrum including 3 different entities: erythroplasia of Queyrat, Bowen disease, and BP.¹ Histologically, PIN also is classified into 3 subtypes according to histological depth of epidermal atypia.¹

Bowenoid papulosis usually is characterized by multiple red-brown or flesh-colored papules that most commonly appear on the shaft or glans of the penis. Bowenoid papulosis frequently is associated with high-risk types of HPV, such as HPV type 16, and is sometimes difficult to differentiate clinically from pigmented condyloma acuminatum. The clinical lesions of BP usually are less papillomatous, smoother topped, more polymorphic, and more coalescent compared to common genital viral condyloma acuminatum.² Bowenoid papulosis usually is seen in young (<30 years of age) sexually active men, unlike the patches or plaques of erythroplasia of Queyrat or Bowen disease, which are seen in older men aged 45 to 75 years. Bowenoid papulosis also has a lower malignancy potential than erythroplasia of Queyrat and Bowen disease.²

Penile melanosis, penile lentigo, and seborrheic keratosis comprise the differential diagnosis of dark spots on the penis and also should be kept in mind. Penile melanosis is the most common cause of dark spots on the penis. When the dark spots have irregular borders and change in color, they may be misdiagnosed as malignant lesions such as melanoma.³ In most cases, biopsy is indicated. Histologically, penile melanosis is characterized by hyperpigmentation of the basal cell layer with no melanocytic hyperplasia. Treatment is unnecessary in most cases.

Penile lentigo presents as small flat pigmented spots on the penile skin with clearly defined margins surrounded by normal-appearing skin. Histologically, it is characterized by hyperplasia of melanocytes above the basement membrane of the epidermis.³

Penile pigmented seborrheic keratosis is a rare clinical entity that can be easily misinterpreted as condyloma acuminatum. Histologically, it is characterized by basal cell hyperplasia with cystic formation in the thickened epidermis. Excisional biopsy may be the only way to rule out malignant disease.

Treatment options for PIN include cryotherapy, CO₂ or Nd:YAG lasers, photodynamic therapy, topical 5-FU or imiquimod therapy, and surgical excision such as Mohs micrographic surgery.^4-9 Although these therapeutic modalities usually are effective, recurrence is common.⁶ The patients' discomfort and poor cosmetic and functional outcomes from the surgical removal of lesions also present a challenge in treatment planning. 

In our patient, we quickly achieved a good result with topical 5-FU, though the disease was in local advanced stage. It is important for clinicians to consider 5-FU as an effective treatment option for PIN before planning surgery.

The Diagnosis: Eruptive Blue Nevus

All biopsies demonstrated similar histologic features, including an intradermal proliferation of heavily pigmented, spindle-shaped dendritic melanocytes (Figure). The dermal pigment was most pronounced in the grossly darker papules, and there was not a substantial amount of background pigmentation at the stratum basale. Cytologic atypia, foci of necrosis, and mitotic activity were absent from all sections. There was no definitive junctional component identified, no multinucleated giant cells, and there was no overlying epidermal aberration. With some background pigmentation seen histologically, nevus spilus was considered, but because this acute eruption occurred in a young adult without appreciable gross background hyperpigmentation, the clinical context led to a diagnosis of eruptive blue nevus. After communicating the findings to the patient, he declined further treatment.

Eruptive blue nevus is an exceptionally rare subtype of blue nevus with few cases reported since the 1940s.^1-9 Generally, each case report found a triggering event that could possibly have precipitated the acute proliferation and evolution of nevi. Triggering events can include bullous processes such as erythema multiforme² and Stevens-Johnson syndrome,³ severe sunburn,⁴ trauma,⁵ immunosuppression,⁶ and a variety of endocrinopathies. No such history could be identified in our patient, except the biopsy.

Common blue nevi are benign, usually congenital, well-circumscribed, solitary, blue-gray macules or papules. Half of blue nevi cases are found on the dorsal aspects of the hands and feet but can present anywhere (eg, face, scalp, wrists, sacrum, buttocks). The blue-gray color appreciated clinically is attributed to the Tyndall effect, which occurs when long-wavelength light--red, orange, and yellow--is absorbed by the melanin deep in the dermis, while short-wavelength visible light--blue, violet, and indigo--is reflected with backscattering. On polarized dermoscopy, a homogeneous blue-gray hue is appreciated, but lighter segments may be present when collagen deposition is robust. Histopathologic findings confirm spindle-shaped dendritic melanocytes in the dermis without epidermal involvement. It generally is accepted that the etiology of these benign nevi is a failed migration of neural crest cells to the epidermis.^10,11 Although the common blue nevus may be simple to diagnose, several subtypes have been described in the literature, including combined blue nevus, desmoplastic blue nevus, hypomelanotic/amelanotic blue nevus, and epithelioid blue nevus of Carney complex, and excluding a malignant process is of monumental importance.^7,12

Biopsy is recommended for common blue nevi in the evaluation of newly acquired lesions, expansion of previously stable nevi, or for nevi larger than 10 mm in diameter. The nature of eruptive blue nevi warrants a biopsy to exclude melanoma or another malignant process. While the Becker nevus may manifest in adolescent males, it is clinically distinct from an eruptive blue nevus due to the size, relative homogeneity, and presence of hair within the lesion. Cutaneous amyloidosis may appear clinically similar to an eruptive blue nevus, but globular or amorphous material was not present in the papillary dermis of biopsied lesions in our patient. Since there was no cellular atypia or mitotic activity, melanoma and other malignancies were ruled out. Lastly, NAME syndrome by definition must include atrial myxomas, myxoid neurofibromas, and ephelides in addition to the nevi; however, our patient had only nevi and few ephelides. Once the diagnosis is established and benign nature confirmed, treatment is not necessarily required. If the patient elects to remove the lesion for aesthetic reasons, an excision into the subcutaneous fat is required to ensure complete removal of deep dermal melanocytes. Prior excisions of eruptive blue nevi have had no recurrence after more than 10 months.^8,9

The Diagnosis: Eruptive Blue Nevus

All biopsies demonstrated similar histologic features, including an intradermal proliferation of heavily pigmented, spindle-shaped dendritic melanocytes (Figure). The dermal pigment was most pronounced in the grossly darker papules, and there was not a substantial amount of background pigmentation at the stratum basale. Cytologic atypia, foci of necrosis, and mitotic activity were absent from all sections. There was no definitive junctional component identified, no multinucleated giant cells, and there was no overlying epidermal aberration. With some background pigmentation seen histologically, nevus spilus was considered, but because this acute eruption occurred in a young adult without appreciable gross background hyperpigmentation, the clinical context led to a diagnosis of eruptive blue nevus. After communicating the findings to the patient, he declined further treatment.

Eruptive blue nevus is an exceptionally rare subtype of blue nevus with few cases reported since the 1940s.^1-9 Generally, each case report found a triggering event that could possibly have precipitated the acute proliferation and evolution of nevi. Triggering events can include bullous processes such as erythema multiforme² and Stevens-Johnson syndrome,³ severe sunburn,⁴ trauma,⁵ immunosuppression,⁶ and a variety of endocrinopathies. No such history could be identified in our patient, except the biopsy.

Common blue nevi are benign, usually congenital, well-circumscribed, solitary, blue-gray macules or papules. Half of blue nevi cases are found on the dorsal aspects of the hands and feet but can present anywhere (eg, face, scalp, wrists, sacrum, buttocks). The blue-gray color appreciated clinically is attributed to the Tyndall effect, which occurs when long-wavelength light--red, orange, and yellow--is absorbed by the melanin deep in the dermis, while short-wavelength visible light--blue, violet, and indigo--is reflected with backscattering. On polarized dermoscopy, a homogeneous blue-gray hue is appreciated, but lighter segments may be present when collagen deposition is robust. Histopathologic findings confirm spindle-shaped dendritic melanocytes in the dermis without epidermal involvement. It generally is accepted that the etiology of these benign nevi is a failed migration of neural crest cells to the epidermis.^10,11 Although the common blue nevus may be simple to diagnose, several subtypes have been described in the literature, including combined blue nevus, desmoplastic blue nevus, hypomelanotic/amelanotic blue nevus, and epithelioid blue nevus of Carney complex, and excluding a malignant process is of monumental importance.^7,12

Biopsy is recommended for common blue nevi in the evaluation of newly acquired lesions, expansion of previously stable nevi, or for nevi larger than 10 mm in diameter. The nature of eruptive blue nevi warrants a biopsy to exclude melanoma or another malignant process. While the Becker nevus may manifest in adolescent males, it is clinically distinct from an eruptive blue nevus due to the size, relative homogeneity, and presence of hair within the lesion. Cutaneous amyloidosis may appear clinically similar to an eruptive blue nevus, but globular or amorphous material was not present in the papillary dermis of biopsied lesions in our patient. Since there was no cellular atypia or mitotic activity, melanoma and other malignancies were ruled out. Lastly, NAME syndrome by definition must include atrial myxomas, myxoid neurofibromas, and ephelides in addition to the nevi; however, our patient had only nevi and few ephelides. Once the diagnosis is established and benign nature confirmed, treatment is not necessarily required. If the patient elects to remove the lesion for aesthetic reasons, an excision into the subcutaneous fat is required to ensure complete removal of deep dermal melanocytes. Prior excisions of eruptive blue nevi have had no recurrence after more than 10 months.^8,9

The Diagnosis: Eruptive Blue Nevus

All biopsies demonstrated similar histologic features, including an intradermal proliferation of heavily pigmented, spindle-shaped dendritic melanocytes (Figure). The dermal pigment was most pronounced in the grossly darker papules, and there was not a substantial amount of background pigmentation at the stratum basale. Cytologic atypia, foci of necrosis, and mitotic activity were absent from all sections. There was no definitive junctional component identified, no multinucleated giant cells, and there was no overlying epidermal aberration. With some background pigmentation seen histologically, nevus spilus was considered, but because this acute eruption occurred in a young adult without appreciable gross background hyperpigmentation, the clinical context led to a diagnosis of eruptive blue nevus. After communicating the findings to the patient, he declined further treatment.

Eruptive blue nevus is an exceptionally rare subtype of blue nevus with few cases reported since the 1940s.^1-9 Generally, each case report found a triggering event that could possibly have precipitated the acute proliferation and evolution of nevi. Triggering events can include bullous processes such as erythema multiforme² and Stevens-Johnson syndrome,³ severe sunburn,⁴ trauma,⁵ immunosuppression,⁶ and a variety of endocrinopathies. No such history could be identified in our patient, except the biopsy.

Common blue nevi are benign, usually congenital, well-circumscribed, solitary, blue-gray macules or papules. Half of blue nevi cases are found on the dorsal aspects of the hands and feet but can present anywhere (eg, face, scalp, wrists, sacrum, buttocks). The blue-gray color appreciated clinically is attributed to the Tyndall effect, which occurs when long-wavelength light--red, orange, and yellow--is absorbed by the melanin deep in the dermis, while short-wavelength visible light--blue, violet, and indigo--is reflected with backscattering. On polarized dermoscopy, a homogeneous blue-gray hue is appreciated, but lighter segments may be present when collagen deposition is robust. Histopathologic findings confirm spindle-shaped dendritic melanocytes in the dermis without epidermal involvement. It generally is accepted that the etiology of these benign nevi is a failed migration of neural crest cells to the epidermis.^10,11 Although the common blue nevus may be simple to diagnose, several subtypes have been described in the literature, including combined blue nevus, desmoplastic blue nevus, hypomelanotic/amelanotic blue nevus, and epithelioid blue nevus of Carney complex, and excluding a malignant process is of monumental importance.^7,12

Biopsy is recommended for common blue nevi in the evaluation of newly acquired lesions, expansion of previously stable nevi, or for nevi larger than 10 mm in diameter. The nature of eruptive blue nevi warrants a biopsy to exclude melanoma or another malignant process. While the Becker nevus may manifest in adolescent males, it is clinically distinct from an eruptive blue nevus due to the size, relative homogeneity, and presence of hair within the lesion. Cutaneous amyloidosis may appear clinically similar to an eruptive blue nevus, but globular or amorphous material was not present in the papillary dermis of biopsied lesions in our patient. Since there was no cellular atypia or mitotic activity, melanoma and other malignancies were ruled out. Lastly, NAME syndrome by definition must include atrial myxomas, myxoid neurofibromas, and ephelides in addition to the nevi; however, our patient had only nevi and few ephelides. Once the diagnosis is established and benign nature confirmed, treatment is not necessarily required. If the patient elects to remove the lesion for aesthetic reasons, an excision into the subcutaneous fat is required to ensure complete removal of deep dermal melanocytes. Prior excisions of eruptive blue nevi have had no recurrence after more than 10 months.^8,9

The Cutis Editorial Board is now accepting applications for the 2019 Resident Corner column. The Editorial Board will select 2 residents to serve as the Resident Corner columnists for 1 year (3 articles each). Articles are posted online only but will be referenced in Index Medicus. All applicants must be current residents and will still be in residency throughout 2019.

For consideration, send your curriculum vitae along with a brief (not to exceed 500 words) statement of why you enjoy Cutis and what you can offer your fellow residents in contributing a monthly column.

All materials should be submitted via email as 1 Word document to Melissa Sears by November 1. The residents who are selected to write the column for the upcoming year will be notified by November 15.

We look forward to continuing to educate dermatology residents on topics that are most important to them!

The Cutis Editorial Board is now accepting applications for the 2019 Resident Corner column. The Editorial Board will select 2 residents to serve as the Resident Corner columnists for 1 year (3 articles each). Articles are posted online only but will be referenced in Index Medicus. All applicants must be current residents and will still be in residency throughout 2019.

For consideration, send your curriculum vitae along with a brief (not to exceed 500 words) statement of why you enjoy Cutis and what you can offer your fellow residents in contributing a monthly column.

All materials should be submitted via email as 1 Word document to Melissa Sears by November 1. The residents who are selected to write the column for the upcoming year will be notified by November 15.

We look forward to continuing to educate dermatology residents on topics that are most important to them!

The Cutis Editorial Board is now accepting applications for the 2019 Resident Corner column. The Editorial Board will select 2 residents to serve as the Resident Corner columnists for 1 year (3 articles each). Articles are posted online only but will be referenced in Index Medicus. All applicants must be current residents and will still be in residency throughout 2019.

For consideration, send your curriculum vitae along with a brief (not to exceed 500 words) statement of why you enjoy Cutis and what you can offer your fellow residents in contributing a monthly column.

All materials should be submitted via email as 1 Word document to Melissa Sears by November 1. The residents who are selected to write the column for the upcoming year will be notified by November 15.

We look forward to continuing to educate dermatology residents on topics that are most important to them!

The cutaneous manifestations of Crohn disease (CD) are varied, including pyoderma gangrenosum, erythema nodosum, and metastatic CD (MCD). First described by Parks et al,¹ MCD is defined as the occurrence of granulomatous lesions at a skin site distant from the gastrointestinal tract.^1-20 Metastatic CD presents a diagnostic challenge because it is a rare component in the spectrum of inflammatory bowel disease complications, and many physicians are unaware of its existence. It may precede, coincide with, or develop after the diagnosis of intestinal disease.^2-5 Vulvoperineal involvement is particularly problematic because a multitude of other, more likely disease processes are considered first. Typically it is initially diagnosed as a presumed infection prompting reflexive treatment with antivirals, antifungals, and antibiotics. Patients may experience symptoms for years prior to correct diagnosis and institution of proper therapy. A variety of clinical presentations have been described, including nonspecific pain and swelling, erythematous papules and plaques, and nonhealing ulcers. Skin biopsy characteristically confirms the diagnosis and reveals dermal noncaseating granulomas. Multiple oral and parenteral therapies are available, with surgical intervention reserved for resistant cases. We present a case of vulvovaginal MCD in the setting of well-controlled intestinal disease. We also provide a review of the literature regarding genital CD and emphasize the need to keep MCD in the differential of vulvoperineal pathology.

Case Report

A 29-year-old woman was referred to the dermatology clinic with vulvar pain, swelling, and pruritus of 14 months’ duration. Her medical history was remarkable for CD following a colectomy with colostomy. Prior therapies included methotrexate with infliximab for 5 years followed by a 2-year regimen with adalimumab, which induced remission of the intestinal disease.

The patient previously had taken a variety of topical and oral antimicrobials based on treatment from a primary care physician because fungal, bacterial, and viral infections initially were suspected; however, the vulvar disease persisted, and drug-induced immunosuppression was considered to be an underlying factor. Thus, adalimumab was discontinued. Despite elimination of the biologic, the vulvar disease progressed, which prompted referral to the dermatology clinic.

Physical examination revealed diffuse vulvar edema with overlying erythema and scale (Figure 1A). Upon closer inspection, scattered violaceous papules atop a backdrop of lichenification were evident, imparting a cobblestone appearance (Figure 1B). Additionally, a fissure was present on the gluteal cleft. Biopsy from the left labia majora demonstrated well-formed granulomas within a fibrotic reticular dermis (Figures 2A and 2B). The granulomas consisted of both mononucleated and multinucleated histiocytes, rimmed peripherally by lymphocytes and plasma cells (Figure 2C). Periodic acid–Schiff–diastase and acid-fast bacilli stains as well as polarizing microscopy were negative.

Comment

Crohn disease is an idiopathic chronic inflammatory condition that primarily affects the gastrointestinal tract, anywhere from the mouth to the anus. It is characterized by transmural inflammation and fissures that can extend beyond the muscularis propria.^4,6 Extraintestinal manifestations are common.³

Cutaneous CD often presents as perianal, perifistular, or peristomal inflammation or ulceration.⁷ Other skin manifestations include pyoderma gangrenosum, erythema nodosum, erythema multiforme, epidermolysis bullosa acquisita, and palmar erythema.⁷ Metastatic CD involves skin noncontiguous with the gastrointestinal tract^1-20 and may involve any portion of the cutis. Although rare, MCD is the typical etiology underlying vulvar CD.⁸

Approximately 20% of MCD patients have cutaneous lesions without a history of gastrointestinal disease. More than half of cases in adults and approximately two-thirds in children involve the genitalia. Although more common in adults, vulvar involvement has been reported in children as young as 6 years of age.² Diagnosis is especially challenging when bowel symptoms are absent; those patients should be evaluated and followed for subsequent intestinal involvement.⁶

Clinically, symptoms may include general discomfort, pain, pruritus, and dyspareunia. Psychosocial and sexual dysfunction are prevalent and also should be addressed.⁹ Depending on the stage of the disease, physical examination may reveal erythema, edema, papules, pustules, nodules, condylomatous lesions, abscesses, fissures, fistulas, ulceration, acrochordons, and scarring.^2-6,10,11

A host of infections (ie, mycobacterial, actinomycosis, deep fungal, sexually transmitted, schistosomiasis), inflammatory conditions (ie, sarcoid, hidradenitis suppurativa), foreign body reactions, Melkersson-Rosenthal syndrome, and sexual abuse should be included in the differential diagnosis.^2,6,10-12 Once infection, sarcoid, and foreign body reaction have been ruled out, noncaseating granulomas in skin are highly suggestive of CD.⁷

Histopathologic findings of MCD reveal myriad morphological reaction patterns,^5,13 including high-grade dysplasia and carcinoma of the vulva; therefore, it may be imprudent to withhold diagnosis based on the absence of the historically pathognomonic noncaseating granulomas.⁵

The etiopathogenesis of MCD remains an enigma. Dermatopathologic examinations consistently reveal a vascular injury syndrome,¹³ implicating a possible circulatory system contribution via deposition of immune complexes or antigens in skin.⁷ Bacterial infection has been implicated in the intestinal manifestations of CD; however, failure to detect microbial ribosomal RNA in MCD biopsies refutes theories of hematogenous spread of microbes.¹³ Another plausible explanation is that antibodies are formed to conserved microbial epitopes following loss of tolerance to gut flora, which results in an excessive immunologic response at distinct sites in susceptible individuals.¹³ A T-lymphocyte–mediated type IV hypersensitivity reaction also has been proposed via cross-reactivity of lymphocytes, with skin antigens precipitating extraintestinal granuloma formation and vascular injury.³ Clearly, further investigation is needed.

Magnetic resonanance imaging can identify the extent and anatomy of intestinal and pelvic disease and can assist in the diagnosis of vulvar CD.^10,11,14 For these reasons, some experts propose that imaging should be instituted prior to therapy,^12,15,16 especially when direct extension is suspected.¹⁷

Treatment is challenging and often involves collaboration among several specialties.¹² Many treatment options exist because therapeutic responses vary and genital MCD is frequently recalcitrant to therapy.⁴ Medical therapy includes antibiotics such as metronidazole, corticosteroids (ie, topical, intralesional, systemic), and immune modulators (eg, azathioprine, 6-mercaptopurine, cyclosporine, methotrexate, mycophenolate mofetil, tumor necrosis factor α inhibitors).^{2,3,6,10,16,18} Thalidomide has been used for refractory cases.¹⁹ These treatments can be used alone or in combination. Patients should be monitored for side effects and informed that many treatment regimens may be required before a sustained response is achieved.^4,16,18 Surgery is reserved for the most resistant cases. Extensive radical excision of the involved area is the best approach, as limited local excision often is followed by recurrence.²⁰

Conclusion

Our case highlights that vulvar CD can develop in the setting of well-controlled intestinal disease. Vulvoperineal CD should be considered in the differential diagnosis of chronic vulvar pain, swelling, and pruritus, especially in cases resistant to standard therapies and regardless of whether or not gastrointestinal tract symptoms are present. Physicians must be cognizant that vulvar signs and symptoms may precede, coincide with, or follow the diagnosis of intestinal CD. Increased awareness of this entity may facilitate its early recognition and prompt more timely treatment among women with vulvar disease caused by MCD.

The cutaneous manifestations of Crohn disease (CD) are varied, including pyoderma gangrenosum, erythema nodosum, and metastatic CD (MCD). First described by Parks et al,¹ MCD is defined as the occurrence of granulomatous lesions at a skin site distant from the gastrointestinal tract.^1-20 Metastatic CD presents a diagnostic challenge because it is a rare component in the spectrum of inflammatory bowel disease complications, and many physicians are unaware of its existence. It may precede, coincide with, or develop after the diagnosis of intestinal disease.^2-5 Vulvoperineal involvement is particularly problematic because a multitude of other, more likely disease processes are considered first. Typically it is initially diagnosed as a presumed infection prompting reflexive treatment with antivirals, antifungals, and antibiotics. Patients may experience symptoms for years prior to correct diagnosis and institution of proper therapy. A variety of clinical presentations have been described, including nonspecific pain and swelling, erythematous papules and plaques, and nonhealing ulcers. Skin biopsy characteristically confirms the diagnosis and reveals dermal noncaseating granulomas. Multiple oral and parenteral therapies are available, with surgical intervention reserved for resistant cases. We present a case of vulvovaginal MCD in the setting of well-controlled intestinal disease. We also provide a review of the literature regarding genital CD and emphasize the need to keep MCD in the differential of vulvoperineal pathology.

Case Report

A 29-year-old woman was referred to the dermatology clinic with vulvar pain, swelling, and pruritus of 14 months’ duration. Her medical history was remarkable for CD following a colectomy with colostomy. Prior therapies included methotrexate with infliximab for 5 years followed by a 2-year regimen with adalimumab, which induced remission of the intestinal disease.

The patient previously had taken a variety of topical and oral antimicrobials based on treatment from a primary care physician because fungal, bacterial, and viral infections initially were suspected; however, the vulvar disease persisted, and drug-induced immunosuppression was considered to be an underlying factor. Thus, adalimumab was discontinued. Despite elimination of the biologic, the vulvar disease progressed, which prompted referral to the dermatology clinic.

Physical examination revealed diffuse vulvar edema with overlying erythema and scale (Figure 1A). Upon closer inspection, scattered violaceous papules atop a backdrop of lichenification were evident, imparting a cobblestone appearance (Figure 1B). Additionally, a fissure was present on the gluteal cleft. Biopsy from the left labia majora demonstrated well-formed granulomas within a fibrotic reticular dermis (Figures 2A and 2B). The granulomas consisted of both mononucleated and multinucleated histiocytes, rimmed peripherally by lymphocytes and plasma cells (Figure 2C). Periodic acid–Schiff–diastase and acid-fast bacilli stains as well as polarizing microscopy were negative.

Comment

Crohn disease is an idiopathic chronic inflammatory condition that primarily affects the gastrointestinal tract, anywhere from the mouth to the anus. It is characterized by transmural inflammation and fissures that can extend beyond the muscularis propria.^4,6 Extraintestinal manifestations are common.³

Cutaneous CD often presents as perianal, perifistular, or peristomal inflammation or ulceration.⁷ Other skin manifestations include pyoderma gangrenosum, erythema nodosum, erythema multiforme, epidermolysis bullosa acquisita, and palmar erythema.⁷ Metastatic CD involves skin noncontiguous with the gastrointestinal tract^1-20 and may involve any portion of the cutis. Although rare, MCD is the typical etiology underlying vulvar CD.⁸

Approximately 20% of MCD patients have cutaneous lesions without a history of gastrointestinal disease. More than half of cases in adults and approximately two-thirds in children involve the genitalia. Although more common in adults, vulvar involvement has been reported in children as young as 6 years of age.² Diagnosis is especially challenging when bowel symptoms are absent; those patients should be evaluated and followed for subsequent intestinal involvement.⁶

Clinically, symptoms may include general discomfort, pain, pruritus, and dyspareunia. Psychosocial and sexual dysfunction are prevalent and also should be addressed.⁹ Depending on the stage of the disease, physical examination may reveal erythema, edema, papules, pustules, nodules, condylomatous lesions, abscesses, fissures, fistulas, ulceration, acrochordons, and scarring.^2-6,10,11

A host of infections (ie, mycobacterial, actinomycosis, deep fungal, sexually transmitted, schistosomiasis), inflammatory conditions (ie, sarcoid, hidradenitis suppurativa), foreign body reactions, Melkersson-Rosenthal syndrome, and sexual abuse should be included in the differential diagnosis.^2,6,10-12 Once infection, sarcoid, and foreign body reaction have been ruled out, noncaseating granulomas in skin are highly suggestive of CD.⁷

Histopathologic findings of MCD reveal myriad morphological reaction patterns,^5,13 including high-grade dysplasia and carcinoma of the vulva; therefore, it may be imprudent to withhold diagnosis based on the absence of the historically pathognomonic noncaseating granulomas.⁵

The etiopathogenesis of MCD remains an enigma. Dermatopathologic examinations consistently reveal a vascular injury syndrome,¹³ implicating a possible circulatory system contribution via deposition of immune complexes or antigens in skin.⁷ Bacterial infection has been implicated in the intestinal manifestations of CD; however, failure to detect microbial ribosomal RNA in MCD biopsies refutes theories of hematogenous spread of microbes.¹³ Another plausible explanation is that antibodies are formed to conserved microbial epitopes following loss of tolerance to gut flora, which results in an excessive immunologic response at distinct sites in susceptible individuals.¹³ A T-lymphocyte–mediated type IV hypersensitivity reaction also has been proposed via cross-reactivity of lymphocytes, with skin antigens precipitating extraintestinal granuloma formation and vascular injury.³ Clearly, further investigation is needed.

Magnetic resonanance imaging can identify the extent and anatomy of intestinal and pelvic disease and can assist in the diagnosis of vulvar CD.^10,11,14 For these reasons, some experts propose that imaging should be instituted prior to therapy,^12,15,16 especially when direct extension is suspected.¹⁷

Treatment is challenging and often involves collaboration among several specialties.¹² Many treatment options exist because therapeutic responses vary and genital MCD is frequently recalcitrant to therapy.⁴ Medical therapy includes antibiotics such as metronidazole, corticosteroids (ie, topical, intralesional, systemic), and immune modulators (eg, azathioprine, 6-mercaptopurine, cyclosporine, methotrexate, mycophenolate mofetil, tumor necrosis factor α inhibitors).^{2,3,6,10,16,18} Thalidomide has been used for refractory cases.¹⁹ These treatments can be used alone or in combination. Patients should be monitored for side effects and informed that many treatment regimens may be required before a sustained response is achieved.^4,16,18 Surgery is reserved for the most resistant cases. Extensive radical excision of the involved area is the best approach, as limited local excision often is followed by recurrence.²⁰

Conclusion

Our case highlights that vulvar CD can develop in the setting of well-controlled intestinal disease. Vulvoperineal CD should be considered in the differential diagnosis of chronic vulvar pain, swelling, and pruritus, especially in cases resistant to standard therapies and regardless of whether or not gastrointestinal tract symptoms are present. Physicians must be cognizant that vulvar signs and symptoms may precede, coincide with, or follow the diagnosis of intestinal CD. Increased awareness of this entity may facilitate its early recognition and prompt more timely treatment among women with vulvar disease caused by MCD.

The cutaneous manifestations of Crohn disease (CD) are varied, including pyoderma gangrenosum, erythema nodosum, and metastatic CD (MCD). First described by Parks et al,¹ MCD is defined as the occurrence of granulomatous lesions at a skin site distant from the gastrointestinal tract.^1-20 Metastatic CD presents a diagnostic challenge because it is a rare component in the spectrum of inflammatory bowel disease complications, and many physicians are unaware of its existence. It may precede, coincide with, or develop after the diagnosis of intestinal disease.^2-5 Vulvoperineal involvement is particularly problematic because a multitude of other, more likely disease processes are considered first. Typically it is initially diagnosed as a presumed infection prompting reflexive treatment with antivirals, antifungals, and antibiotics. Patients may experience symptoms for years prior to correct diagnosis and institution of proper therapy. A variety of clinical presentations have been described, including nonspecific pain and swelling, erythematous papules and plaques, and nonhealing ulcers. Skin biopsy characteristically confirms the diagnosis and reveals dermal noncaseating granulomas. Multiple oral and parenteral therapies are available, with surgical intervention reserved for resistant cases. We present a case of vulvovaginal MCD in the setting of well-controlled intestinal disease. We also provide a review of the literature regarding genital CD and emphasize the need to keep MCD in the differential of vulvoperineal pathology.

Case Report

A 29-year-old woman was referred to the dermatology clinic with vulvar pain, swelling, and pruritus of 14 months’ duration. Her medical history was remarkable for CD following a colectomy with colostomy. Prior therapies included methotrexate with infliximab for 5 years followed by a 2-year regimen with adalimumab, which induced remission of the intestinal disease.

The patient previously had taken a variety of topical and oral antimicrobials based on treatment from a primary care physician because fungal, bacterial, and viral infections initially were suspected; however, the vulvar disease persisted, and drug-induced immunosuppression was considered to be an underlying factor. Thus, adalimumab was discontinued. Despite elimination of the biologic, the vulvar disease progressed, which prompted referral to the dermatology clinic.

Physical examination revealed diffuse vulvar edema with overlying erythema and scale (Figure 1A). Upon closer inspection, scattered violaceous papules atop a backdrop of lichenification were evident, imparting a cobblestone appearance (Figure 1B). Additionally, a fissure was present on the gluteal cleft. Biopsy from the left labia majora demonstrated well-formed granulomas within a fibrotic reticular dermis (Figures 2A and 2B). The granulomas consisted of both mononucleated and multinucleated histiocytes, rimmed peripherally by lymphocytes and plasma cells (Figure 2C). Periodic acid–Schiff–diastase and acid-fast bacilli stains as well as polarizing microscopy were negative.

Comment

Crohn disease is an idiopathic chronic inflammatory condition that primarily affects the gastrointestinal tract, anywhere from the mouth to the anus. It is characterized by transmural inflammation and fissures that can extend beyond the muscularis propria.^4,6 Extraintestinal manifestations are common.³

Cutaneous CD often presents as perianal, perifistular, or peristomal inflammation or ulceration.⁷ Other skin manifestations include pyoderma gangrenosum, erythema nodosum, erythema multiforme, epidermolysis bullosa acquisita, and palmar erythema.⁷ Metastatic CD involves skin noncontiguous with the gastrointestinal tract^1-20 and may involve any portion of the cutis. Although rare, MCD is the typical etiology underlying vulvar CD.⁸

Approximately 20% of MCD patients have cutaneous lesions without a history of gastrointestinal disease. More than half of cases in adults and approximately two-thirds in children involve the genitalia. Although more common in adults, vulvar involvement has been reported in children as young as 6 years of age.² Diagnosis is especially challenging when bowel symptoms are absent; those patients should be evaluated and followed for subsequent intestinal involvement.⁶

Clinically, symptoms may include general discomfort, pain, pruritus, and dyspareunia. Psychosocial and sexual dysfunction are prevalent and also should be addressed.⁹ Depending on the stage of the disease, physical examination may reveal erythema, edema, papules, pustules, nodules, condylomatous lesions, abscesses, fissures, fistulas, ulceration, acrochordons, and scarring.^2-6,10,11

A host of infections (ie, mycobacterial, actinomycosis, deep fungal, sexually transmitted, schistosomiasis), inflammatory conditions (ie, sarcoid, hidradenitis suppurativa), foreign body reactions, Melkersson-Rosenthal syndrome, and sexual abuse should be included in the differential diagnosis.^2,6,10-12 Once infection, sarcoid, and foreign body reaction have been ruled out, noncaseating granulomas in skin are highly suggestive of CD.⁷

Histopathologic findings of MCD reveal myriad morphological reaction patterns,^5,13 including high-grade dysplasia and carcinoma of the vulva; therefore, it may be imprudent to withhold diagnosis based on the absence of the historically pathognomonic noncaseating granulomas.⁵

The etiopathogenesis of MCD remains an enigma. Dermatopathologic examinations consistently reveal a vascular injury syndrome,¹³ implicating a possible circulatory system contribution via deposition of immune complexes or antigens in skin.⁷ Bacterial infection has been implicated in the intestinal manifestations of CD; however, failure to detect microbial ribosomal RNA in MCD biopsies refutes theories of hematogenous spread of microbes.¹³ Another plausible explanation is that antibodies are formed to conserved microbial epitopes following loss of tolerance to gut flora, which results in an excessive immunologic response at distinct sites in susceptible individuals.¹³ A T-lymphocyte–mediated type IV hypersensitivity reaction also has been proposed via cross-reactivity of lymphocytes, with skin antigens precipitating extraintestinal granuloma formation and vascular injury.³ Clearly, further investigation is needed.

Magnetic resonanance imaging can identify the extent and anatomy of intestinal and pelvic disease and can assist in the diagnosis of vulvar CD.^10,11,14 For these reasons, some experts propose that imaging should be instituted prior to therapy,^12,15,16 especially when direct extension is suspected.¹⁷

Treatment is challenging and often involves collaboration among several specialties.¹² Many treatment options exist because therapeutic responses vary and genital MCD is frequently recalcitrant to therapy.⁴ Medical therapy includes antibiotics such as metronidazole, corticosteroids (ie, topical, intralesional, systemic), and immune modulators (eg, azathioprine, 6-mercaptopurine, cyclosporine, methotrexate, mycophenolate mofetil, tumor necrosis factor α inhibitors).^{2,3,6,10,16,18} Thalidomide has been used for refractory cases.¹⁹ These treatments can be used alone or in combination. Patients should be monitored for side effects and informed that many treatment regimens may be required before a sustained response is achieved.^4,16,18 Surgery is reserved for the most resistant cases. Extensive radical excision of the involved area is the best approach, as limited local excision often is followed by recurrence.²⁰

Conclusion

Our case highlights that vulvar CD can develop in the setting of well-controlled intestinal disease. Vulvoperineal CD should be considered in the differential diagnosis of chronic vulvar pain, swelling, and pruritus, especially in cases resistant to standard therapies and regardless of whether or not gastrointestinal tract symptoms are present. Physicians must be cognizant that vulvar signs and symptoms may precede, coincide with, or follow the diagnosis of intestinal CD. Increased awareness of this entity may facilitate its early recognition and prompt more timely treatment among women with vulvar disease caused by MCD.

To the Editor:

Microcystic adnexal carcinoma (MAC), described by Goldstein et al¹ in 1982, is a relatively uncommon cutaneous neoplasm. This locally aggressive malignant adnexal tumor has high potential for local recurrence. The skin of the head, particularly in the nasolabial and periorbital regions, most often is involved.² Involvement of the external auditory canal (EAC) is relatively rare. We report a case of MAC of the EAC.

A 52-year-old man presented with 1 palpable nodule on the right EAC of approximately 1 year’s duration. The lesion was asymptomatic, and the patient had no history of radiation exposure. The patient was an airport employee required to wear an earplug in the right ear. Endoscopic examination identified a 1×1 cm² erythematous nodule on the anterior inferior quadrant of the right external ear canal orifice (Figure 1). Axial and coronal computed tomography demonstrated a soft tissue mass in the right EAC without any bony erosion. No clinical signs of regional lymphadenopathy or distant metastasis were present. Excision was performed under microscopic visualization.

Histopathology of the nodule showed marked proliferation of multiple keratin-containing cysts, irregular ductal structures, and solid epithelial nests in the deep dermis (Figure 2). Irregular ductal structures with 2 cell layer walls and several epithelial strands or small nests of tumor cells within desmoplastic stroma were noted (Figure 3). No perineural infiltration or tumor infiltration existed at the margin. Based on the clinical and histopathologic findings, the final diagnosis was MAC. Complete resolution was noted after the excision. The patient returned for regular follow-up and no signs of recurrence were noted for 7 years postoperatively.

Microcystic adnexal carcinoma, also known as sclerosing sweat duct (syringomatous) carcinoma, malignant syringoma, and syringoid eccrine carcinoma, is characterized by slow and locally aggressive growth with high likelihood of perineural invasion and frequent recurrence.² Regional lymph node metastasis is uncommon, and systemic metastasis is rare.^2-4

Although the head most often is involved, a PubMed search of articles indexed for MEDLINE using the terms microcystic adnexal carcinoma and external auditory canal revealed 4 cases (Table).^5-8 Our report adds another case of MAC arising solely in the EAC. Although the etiology of MAC is unknown, prior studies indicated that radiotherapy is a risk factor for MAC. Other possible risk factors include UV light exposure and immunodeficiency.² Our patient had no history of these factors and experienced chronic friction caused by use of an occupational unilateral earplug, which may be a notable factor. Locations of MAC arising outside the head region include the axilla, vulva, breast, palm, toe, perianal skin, buttock, chest, and an ovarian cystic teratoma.^3,9 Friction commonly occurs in many of these areas. Therefore, we propose that friction may be a risk factor for MAC.

Microcystic adnexal carcinoma should be included in the differential diagnosis of any slowly growing cutaneous tumor, even in the EAC. Once diagnosed, the tumor should be surgically excised. Because local recurrence is common and may occur several decades after excision, lifetime follow-up for recurrence signs is essential.

To the Editor:

Microcystic adnexal carcinoma (MAC), described by Goldstein et al¹ in 1982, is a relatively uncommon cutaneous neoplasm. This locally aggressive malignant adnexal tumor has high potential for local recurrence. The skin of the head, particularly in the nasolabial and periorbital regions, most often is involved.² Involvement of the external auditory canal (EAC) is relatively rare. We report a case of MAC of the EAC.

A 52-year-old man presented with 1 palpable nodule on the right EAC of approximately 1 year’s duration. The lesion was asymptomatic, and the patient had no history of radiation exposure. The patient was an airport employee required to wear an earplug in the right ear. Endoscopic examination identified a 1×1 cm² erythematous nodule on the anterior inferior quadrant of the right external ear canal orifice (Figure 1). Axial and coronal computed tomography demonstrated a soft tissue mass in the right EAC without any bony erosion. No clinical signs of regional lymphadenopathy or distant metastasis were present. Excision was performed under microscopic visualization.

Histopathology of the nodule showed marked proliferation of multiple keratin-containing cysts, irregular ductal structures, and solid epithelial nests in the deep dermis (Figure 2). Irregular ductal structures with 2 cell layer walls and several epithelial strands or small nests of tumor cells within desmoplastic stroma were noted (Figure 3). No perineural infiltration or tumor infiltration existed at the margin. Based on the clinical and histopathologic findings, the final diagnosis was MAC. Complete resolution was noted after the excision. The patient returned for regular follow-up and no signs of recurrence were noted for 7 years postoperatively.

Microcystic adnexal carcinoma, also known as sclerosing sweat duct (syringomatous) carcinoma, malignant syringoma, and syringoid eccrine carcinoma, is characterized by slow and locally aggressive growth with high likelihood of perineural invasion and frequent recurrence.² Regional lymph node metastasis is uncommon, and systemic metastasis is rare.^2-4

Although the head most often is involved, a PubMed search of articles indexed for MEDLINE using the terms microcystic adnexal carcinoma and external auditory canal revealed 4 cases (Table).^5-8 Our report adds another case of MAC arising solely in the EAC. Although the etiology of MAC is unknown, prior studies indicated that radiotherapy is a risk factor for MAC. Other possible risk factors include UV light exposure and immunodeficiency.² Our patient had no history of these factors and experienced chronic friction caused by use of an occupational unilateral earplug, which may be a notable factor. Locations of MAC arising outside the head region include the axilla, vulva, breast, palm, toe, perianal skin, buttock, chest, and an ovarian cystic teratoma.^3,9 Friction commonly occurs in many of these areas. Therefore, we propose that friction may be a risk factor for MAC.

Microcystic adnexal carcinoma should be included in the differential diagnosis of any slowly growing cutaneous tumor, even in the EAC. Once diagnosed, the tumor should be surgically excised. Because local recurrence is common and may occur several decades after excision, lifetime follow-up for recurrence signs is essential.

To the Editor:

Microcystic adnexal carcinoma (MAC), described by Goldstein et al¹ in 1982, is a relatively uncommon cutaneous neoplasm. This locally aggressive malignant adnexal tumor has high potential for local recurrence. The skin of the head, particularly in the nasolabial and periorbital regions, most often is involved.² Involvement of the external auditory canal (EAC) is relatively rare. We report a case of MAC of the EAC.

A 52-year-old man presented with 1 palpable nodule on the right EAC of approximately 1 year’s duration. The lesion was asymptomatic, and the patient had no history of radiation exposure. The patient was an airport employee required to wear an earplug in the right ear. Endoscopic examination identified a 1×1 cm² erythematous nodule on the anterior inferior quadrant of the right external ear canal orifice (Figure 1). Axial and coronal computed tomography demonstrated a soft tissue mass in the right EAC without any bony erosion. No clinical signs of regional lymphadenopathy or distant metastasis were present. Excision was performed under microscopic visualization.

Histopathology of the nodule showed marked proliferation of multiple keratin-containing cysts, irregular ductal structures, and solid epithelial nests in the deep dermis (Figure 2). Irregular ductal structures with 2 cell layer walls and several epithelial strands or small nests of tumor cells within desmoplastic stroma were noted (Figure 3). No perineural infiltration or tumor infiltration existed at the margin. Based on the clinical and histopathologic findings, the final diagnosis was MAC. Complete resolution was noted after the excision. The patient returned for regular follow-up and no signs of recurrence were noted for 7 years postoperatively.

Microcystic adnexal carcinoma, also known as sclerosing sweat duct (syringomatous) carcinoma, malignant syringoma, and syringoid eccrine carcinoma, is characterized by slow and locally aggressive growth with high likelihood of perineural invasion and frequent recurrence.² Regional lymph node metastasis is uncommon, and systemic metastasis is rare.^2-4

Although the head most often is involved, a PubMed search of articles indexed for MEDLINE using the terms microcystic adnexal carcinoma and external auditory canal revealed 4 cases (Table).^5-8 Our report adds another case of MAC arising solely in the EAC. Although the etiology of MAC is unknown, prior studies indicated that radiotherapy is a risk factor for MAC. Other possible risk factors include UV light exposure and immunodeficiency.² Our patient had no history of these factors and experienced chronic friction caused by use of an occupational unilateral earplug, which may be a notable factor. Locations of MAC arising outside the head region include the axilla, vulva, breast, palm, toe, perianal skin, buttock, chest, and an ovarian cystic teratoma.^3,9 Friction commonly occurs in many of these areas. Therefore, we propose that friction may be a risk factor for MAC.

Microcystic adnexal carcinoma should be included in the differential diagnosis of any slowly growing cutaneous tumor, even in the EAC. Once diagnosed, the tumor should be surgically excised. Because local recurrence is common and may occur several decades after excision, lifetime follow-up for recurrence signs is essential.