Verrucous porokeratosis of the gluteal cleft (porokeratosis ptychotropica): a rare disorder easily misdiagnosed.

Porokeratosis represents a heterogeneous group of disorders characterized clinically by a distinctive ridge-like border and histologically by cornoid lamellae. A verrucous variant of porokeratosis involving the gluteal cleft has been recently described. We present 5 new cases and review the current literature to highlight the clinical and histopathologic features of this disorder. Descriptive terms including hyperkeratotic porokeratosis, genitogluteal porokeratosis, porokeratoma, follicular porokeratosis, and porokeratosis ptychotropica have all been used to describe this verrucous variant of porokeratosis involving the gluteal cleft. To avoid further confusion, we propose a consolidation of terminologies and suggest verrucous porokeratosis be added to the commonly described variants of porokeratosis.