Lichen planus associated with chenodeoxycholic acid and ursodeoxycholic acid for gallstone dissolution.

A patient who developed lichen planus while receiving chenodeoxycholic acid and ursodeoxycholic acid therapy for gallstones is described. Skin biopsy was performed and histological examination suggested a drug etiology. An association between lichen planus and liver disease is recognized, but this patient exhibited no clinical or biochemical evidence of liver disease and the rash disappeared after cessation of the bile acid therapy. Bile acids may cause lichen planus. The mechanism is unknown.