A case of genital porokeratosis and review of literature.

We present a case of a 64-year-old uncircumcised male who initially presented to the provider with a 1 year history of a solitary lesion on the glans penis that was clinically diagnosed as porokeratosis of Mabelli. A biopsy on a follow-up visit confirmed provider's clinical suspicion. This article highlights the progression and treatment options for porokeratosis on the male genitalia.

What was known?

Based on limited case reports on genital porokeratosis, medical community was aware of the risk of malignant degeneration but before this case report it was unclear about changes that these lesions underwent.

Introduction

Primary genital porokeratosis is a rare entity but its inclusion in the differential diagnosis of genital lesions is imperative given the known risk of malignant degeneration.

Case Report

A 64-year-old Caucasian male with no personal history of skin cancer presented with a 1 year history of an asymptomatic solitary lesion on the glans penis. In the past, patient had been evaluated by urology for an unrelated issue and during that encounter; urologist was unable to render a diagnosis. Upon referral to dermatology, patient presented with a 6 mm, solitary, erythematous annular macule with a circumferential collaret of scale and a central slightly atrophic region. Highlighting the whole lesion with a skin marking pen and wiping away with an alcohol pad led to selective accentuation of the collaret of scale. Based on examination, provider diagnosed the patient with a solitary porokeratosis and offered to treat with cryotherapy. Given the pain involved, patient declined and agreed to a quarterly follow-up.

After 12 months, patient returned to the provider with now a 1.0 cm, solitary, erythematous annular macule with a more prominent central erythema and atrophy [Figure 1]. Beside from the increase in size, the collaret of scale appeared unchanged. Histology [Figure 2a and b] revealed a focal lymphocytic infiltrate in the papillary dermis with a discrete area of absent granular zone and dyskeratotic cells in the spinous layer underlying a thin tier of compact column of parakeratotic cells; the cornoid lamella.

Figure 1

A 1.0 cm, solitary, erythematous annular macule with a more prominent central erythema and atropy

Figure 2

(a) A thin shave biopsy demonstrating two cornoid lamella at far edges. (b) A magnified view revealed a focal lymphocytic infiltrate in the papillary dermis with a discrete area of absent granular zone and dyskeratotic cells in the spinous layer underlying a thin tier of compact column of parakeratotic cells; the cornoid lamella

Discussion

Porokeratosis as an entity has a broad spectrum of presentation ranging from destructive and disfiguring lesions involving the face[12] to involvement of burn scars[3] to dozens of lesions occurring on sun-exposed extremities.[456]

Clinical variants include porokeratosis of Mabelli, linear porokeratosis, disseminated superficial actinic porokeratosis, and punctuate palmoplantar porokeratosis; but all these share the common feature of cornoid lamella on histologic examination.

A less known clinical variant includes porokeratosis ptychotropica (PP) which was first described by Lucker et al., in 1995.[7] Stone et al., in 1999 described a second case where he used a more descriptive term “bilateral perianal inflammatory verrucous porokeratosis”. Features that distinguish PP from genital porokeratosis include multiple cornoid lamellae on histologic examination, a large pruritic verrucous plaque in the perianal region with satellite lesions.[8] Although subadjacent dermal amyloid has been described in a number of PP cases, it has also been noted in other cases of porokeratosis and may just represent a feature of chronic irritation. It remains to be seen whether this has any diagnostic value in differentiating PP from other forms of porokeratosis.

Porokeratosis of Mabelli, though the most common variant, is a rather rare occurrence in the genital region. A thorough review of the literature to only include cases that represent primary genital porokeratosis [Table 1],[91011121314151617181920] shows as few as 26 total cases reported in adult males,[9] three cases in adult females,[101112] and a single case of linear porokeratosis in an adolescent male.[13] Robinson et al., reported a case of a 39-year-old nulliparous Caucasian female with a 30 year history of perianal lesions starting at 8 year of age and spreading to perineum, medial thighs, and plantar surface of feet by age 23.[21] Other similar case reports where authors reported lesions other than genital area were also excluded. We opted to exclude this case because of involvement of areas other than perineum, plus based on description of perianal lesions author suspects that this may in fact have represented a case of Porokeratosis ptychotropica which both clinically and histologically mimic genital porokeratosis.

Table 1

Summary of published data

Based on review of literature [Table 1], it is evident that overwhelming majority of patients affected are middle-aged males (90%) with on average over a year long history before presenting to the dermatologist. No clear propensity towards a solitary or multiple lesions was evident based on the data.

Given the clonal proliferation, dyskeratotic cells, abnormal keratinocyte maturation, and genetic studies demonstrating overexpression of p53;[22] porokeratosis is considered a premalignant condition. Progression to nonmelanoma skin cancer (especially Bowen's disease and squamous cell carcinoma) is well-documented and estimates range from 6.9 to 30%.[2324] Risk factors include history of undergoing radiation therapy, chronic lesions, lesions on extremities, older age, and linear variant.[2324]

Based on clinical examination, differential diagnosis in our patient also included annular lichen planus, Bowen's disease, candidiasis, irritant/allergic contact dermatitis, and Zoon's balanitis. Treatment options include cryotherapy, electrodessication, photodynamic therapy, CO2 laser, topical 5-fluorouracil (5-FU) and excision. Kluger et al., describes a case of genital porokeratosis that disseminated after a 20 year period where the patient reported symptomatic relief after being treated with 3% topical diclofenac.[25] Shave removal was curative in our patient and at 6 month follow-up patient was noted to be disease free.

This case and review of literature demonstrates the clinical presentation of genital porokeratosis, it highlights different treatment options, and a higher propensity of males being affected by this condition.

What is new?

Our case demonstrated the longitudinal follow-up showing low risk with growth overtime.