Bilateral Porokeratosis Ptychotropica on the Gluteal Cleft: A Case Report and Review of the Literature

Abstract

Porokeratosis ptychotropica (PP) is a rare variant of porokoretosis that is distinctive based on its clinical presentation of pruritic, verrucous papules and plaques that often form a “butterfly” shape, commonly located on the perinatal cleft with extension to the buttocks. Similar to other variants of porokeratosis, it is histologically distinguished by the presence of cornoid lamellae. Proper diagnosis is necessary as some studies suggest that PP may predispose to squamous cell carcinoma. Furthermore, there are limited evidence-based treatment options.

We report the case of a47 year-old-male who presented with a rash on the buttocks and legs for 3 years. Physical exam revealed erythematous, annular, and verrucous plaques on the bilateral periglueteal area and bilateral distal lower extremities. The patient felt that lesions on the legs were disfiguring but otherwise asymptomatic. Biopsy results demonstrated hyperkeratosis and parakeratosis suggestive of cornoid lamellae. Clinical and histologic findings were suggestive of PP. Lesions on the legs were treated with cryotherapy, which resulted in resolution at a 3-month follow-up.

PP remains a diagnostic and therapeutic challenge due to its rarity. No standard of care has been established, though topical calcipotriol, topical imiquimod, topical tretonoin, and cryotherapy have been used with success in the literature. This case highlights unique characteristics of PP in order to aid in early detection and cancer prevention while also describing various treatment modalities.