Indirect immunofluorescence microscopy of lichen planus.

Indirect immunofluorescence microscopy using serum and lesional skin revealed a lichen planus specific antigen (LPSA) in 80% of patients with lichen planus. This antigen is found only in the stratum granulosum and stratum spinosum. It was demonstrated in skin lesions in Caucasians and Negroes in South Africa and the U.S.A. but was not found in the skin of normal people or patients with other dermatoses. Indirect immunofluorescence should prove useful in distinguishing atypical forms of lichen planus from other dermatoses.