LAUSR

A 26yearold woman presented with a 7year history of a lesion on the right side of the gluteal cleft. Initially, it was very itchy; intermittent fissuring and bleeding were also reported by the patient. On review in clinic, a welldefined erythematous scaly plaque measuring approximately 2.5 cm on the right side of the gluteal cleft with a raised hyperkeratotic edge was seen (Figure 1). A punch biopsy of the edge of the lesion showed epidermal hyperkeratosis with multiple areas of compact columns of parakeratosis (cornoid lamella) in the stratum corneum. Underlying the column of parakeratosis was focal hypogranulosis and clumps of dyskeratotic cells (Figure 2). These histopathological features are supportive of a diagnosis of porokeratosis ptychotropica. DISCUSSION