Porokeratosis represents a heterogeneous group of keratinization disorders typified by the presence of annular plaques with distinct, raised borders that include cornoid lamellae. Histopathologically, a cornoid lamella is a column of parakeratotic scale overlying an epidermal invagination that displays nearby dyskeratotic keratinocytes and loss of the granular layer. Porokeratosis ptychotropica constitutes a rare variant that classically presents as a plaque in the gluteal cleft that mimics a dermatitis and microscopically contains numerous cornoid lamellae. We report a 28 year-old man with a two-month history of scrotal burning and itching associated with the development of multiple thin red plaques with distinct elevated borders and a pebbled appearance. Histopathological examination revealed psoriasiform acanthosis and multiple cornoid lamellae, which is consistent with a diagnosis of porokeratosis ptychotropica. Our patient's presentation may represent a distinct variant with clinical features of verrucous porokeratosis and histopathological features of porokeratosis ptychotropica which may suggest that the finding of multiple cornoid lamellae is not unique to porokeratosis ptychotropica.
Wanat KA, Gormley RH, Bennett DD, Kovarik CL. Genitogluteal porokeratosis involving the scrotum: an unusual presentation of an uncommon disease.