Skin, Mucosal lichen planus

Lichen planus is a skin/nail bed or mucosal rash presenting as pink, pruritic, and polygonal papules. It is thought to result from immune-mediated inflammation of unknown cause. The pathologic features are of acute and chronic, inflammatory lichenoid and interface dermatosis. It is characterized by compact hyperkeratosis without parakeratosis, wedge shaped hypergranulosis, saw-toothed rete ridges, and lichenoid inflammatory infiltrate.

The biopsy shows a lichenoid inflammation with a band-like infiltrate involving the dermoepidermal junction, consistent with mucosal lichen planus. Immunofluorescence was performed and the specimen was negative for IgG, IgM, IgA and C3.