Isolated lichen planus of the lower lip.

An idiopathic inflammatory dermatosis, lichen planus (LP) involves the skin, mucosa, or both, in a variety of clinical forms. The involvement of the mucous membranes is seen frequently and usually is asymptomatic, but occasionally, LP can be complicated by extensive painful erosions. We report the case of a 44-year-old man who presented with a 3-year history of isolated lower lip erosions, for which the diagnosis of LP was made. This report represents only the fourth case of LP exclusively localized on the lower lip.