A Rare Case of Porokeratosis Ptychotropica in A 27- Year-Old Female – A Case Report

Abstract

Porokeratosis is an uncommon keratinization disorder of the skin that manifests as keratotic papules or annular plaques that spread centrifugally with a raised border. The cornoid lamella is a distinctive diagnostic feature of this disorder. It consists of columns of parakeratosis overlying the epidermis with associated hypogranulosis and scattered dyskeratotic keratinocytes below the corneal layer.

Ptychotropic porokeratosis (verrucous porokeratosis) is a recently classified but rare clinical variant, found in the genitogluteal region, including the natal cleft and buttocks but also seen in the scrotum, penis or vulva. It may be misdiagnosed for several years as it does not have the characteristic clinical features described in classical porokeratosis. However, a biopsy often yields the diagnosis.

In this report, we present a rare case of porokeratosis ptychotropica in a 27-year-old female who presented with recurrent, itchy hyperkeratotic plaques in the inner thighs and perineal area with distinct histological findings, the first case in African literature. The patient was treated with intralesional administration of 5-fluorouracil administered at intervals for 3 months with significant improvement. A literature search revealed less than 50 cases of genitogluteal porokeratosis are documented worldwide, with none reported in Africa.