Lichen planus pigmentosus.

Lichen planus pigmentosus (LPP) is an uncommon variant of lichen planus that tends to occur in middle-aged individuals with darker pigmented skin. Clinical findings include hyperpigmented, brown to gray-brown macules and patches in sun-exposed areas, typically on the head and neck. Histopathologic features include epidermal atrophy, vacuolar degeneration of the basal layer of the epidermis, perivascular lymphohistiocystic infiltrate in the upper dermis, and dermal melanophages. We present a unique case of LPP that was characterized by an atypical initial inflammatory phase and subsequent circinate lesions with central clearing.