A 56-year-old white man presented to our dermatology clinic with a 5-year history of hyperkeratotic plaques on his intergluteal cleft, buttocks (Figure, A), and bilateral ankles (Figure, B). These lesions were occasionally pruritic and caused footwear-associated discomfort. The buttock lesion had been previously diagnosed as psoriasis but never responded to treatment. His medical history was remarkable for poorly controlled diabetes mellitus type 2 (hemoglobin A1c, 9.1%), hypertension, hyperlipidemia, and chronic low back pain. There was no family history of skin diseases. Physical examination revealed well-defined, slightly scaly purple to gray expansive plaques on the bilateral medial buttocks. On the anterior shins and proximal heels were well-defined hyperkeratotic plaques with a purple to gray color. He also exhibited 0.5- to 2-cm thin pink plaques with hyperkeratotic rims and atrophic centers scattered on his bilateral upper and lower extremities. Two shave biopsy specimens were taken, from his right leg and left buttock (Figure, C).
Broussard KC, Boyd A, Gloeckner Powers J. Thick Intergluteal Cleft and Lower Extremity Plaques. JAMA Dermatol. 2013;149(9):1099-1100. doi:10.1001/jamadermatol.2013.414