Pruritic porokeratotic peno-scrotal plaques: Porokeratosis or porokeratotic epidermal reaction pattern? A report of 10 cases.

Background: Porokeratosis restricted to the genital region is rare with few cases described in the literature. Cases of porokeratosis restricted to the genital region are similar to plaque type of porokeratosis of Mibelli seen elsewhere on the body. We encountered 10 young males with pruritic plaques restricted to the peno-scrotal region, which clinically were not diagnosed as porokeratosis, but on biopsy revealed multiple cornoid lamellae, some of which were seen to arise from eccrine and follicular structures. Aims: The aim of this study is to study lesions restricted to the peno-scrotal region in males, which on biopsy showed cornoid lamellae suggestive of porokeratosis. Methods: Retrospective analysis of available data of patients who were rendered a histological diagnosis of genital porokeratosis. The database consisted of biopsies received in private consultation by the first author in the period January 2000 to March 2013. Results: Ten young men, 8 in their third decade, presented with pruritic plaques restricted to the peno-scrotal region of variable duration. The lesions were well-demarcated on the penis, but ill-defined with a rough granular surface on the scrotum. None of patients were diagnosed clinically as porokeratosis. The lesions were poorly responsive to topical steroid/antifungal treatment, but two patients showed partial improvement with oral isotretinoin. Biopsy in nine patients revealed multiple cornoid lamellae involving epidermis (6) and adnexal structures (3). One patient had a single cornoid lamella. Conclusion: The clinical and histological presentation of these patients is different from typical genital porokeratosis described in the literature and we postulate that these patients have an unusual porokeratotic reaction pattern of the epidermis with multiple cornoid lamellae.