Rapidly extending lesions originating in the perianal area

A 60-year-old man presents with rapidly growing lesions on his face, trunk, axillae, flexural areas, and groin. The lesions appeared 3 months earlier in his perianal area and extended rapidly to other areas. Previously, he was treated with topical agents for atopic dermatitis and seborrheic dermatitis without improvement. Examination reveals disseminated violaceous papules and plaques on the face, trunk, axillae, ...