Porokeratosis ptychotropica: a rare manifestation with typical histological exam

Abstract

Porokeratosis is a disorder of epidermal keratinization characterized clinically by a distinctive ridge-like border, and histologically by cornoid lamellae. The known clinical variants of porokeratosis are: classic porokeratosis of Mibelli, disseminated superficial (actinic) porokeratosis (DSAP), porokeratosis palmaris et plantaris disseminata, linear porokeratosis and punctate porokeratosis. In 1995, a seventh form was described as porokeratosis ptychotropica: a verrucous form resembling psoriasis involving the gluteal cleft presenting on the histological exam multiple cornoid lamellae. There are very few reports in the literature of this clinical variant. The present study describes the case of a healthy male presenting gluteal hyperkeratotic plaques for 22 years. He had been to several dermatologists, none of them had achieved a definitive diagnosis. We present a typical clinical presentation and its dermoscopy findings, in addition to histological examination that confirmed the diagnosis.

Porokeratosis ptychotropica: a diagnostic and therapeutic challenge

“…Patients are commonly misdiagnosed as psoriasis, warts, epidermal naevus, chronic eczemas, dermatophytoses, candidiasis, among others. [4][5][6] Coexistence with other forms of porokeratosis has been reported. 7 The histological difference between PP and other porokeratoses resides in the distribution of the cornoid lamellae.…”

“…Testing for infectious agents is negative. 2,6 In other porokeratoses, genetic studies have suggested a 'pathway defect' where many mutations acting upon keratinocyte proliferation and differentiation lead to the formation of the cornoid lamellae.…”

Disseminated verrucous porokeratosis successfully treated with 5-FU followed by oral isotretinoin- a case report

“…The differential diagnoses include plaque psoriasis, lichen planus and common warts. 7 Risk factors for porokeratosis include family history, light-colored skin, ultraviolet or ionizing radiation exposure, internal malignancies and immunosuppression. 8 Histological examination is crucial for the diagnosis.…”

Porokeratoses—A Comprehensive Review on the Genetics and Metabolomics, Imaging Methods and Management of Common Clinical Variants

“…A central scar-like or hyperpigmented area, polarising-specific white four-dotted clods (rosettes), clues of scale (thick curved parallel lines/cerebriform or papillomatous-like pattern, white or brown diffuse scales, follicular plugs) and a vascular pattern consisting of non-uniformly arranged dots or clods can be noted. Pigmented dots and clods on a reddish-brown background may occasionally occur [59,466,473,486,493,[501][502][503][504][505].…”