Lichen planus dermopathy: demonstration of a lichen planus specific epidermal antigen in affected patients.

Lichen planus is a common papulosquamous disorder of skin and mucous membranes of unknown etiology. Studies reported here demonstrate a lichen planus specific antigen (LPSA) in granular and deep prickle epithelial cells from the lichen planus lesion. Sera from seven out of eight lichen planus patients tested contained an antibody to LPSA. The LPSA was not detected in normal skin tissues from lichen planus patients, or in skin from normal donors and skin from patients with skin disorders other than lichen planus. A serologic survey of serum from people with no clinical history of lichen planus revealed approximately a 7% incidence of antibody to LPSA. These studies suggest that LPSA may be of exogenous origin.