Lichen planus: a study of 72 cases in Singapore.

Seventy-two patients attending this hospital with a diagnosis of lichen planus were examined. There was a striking predominance of Indians (69%) and a surprisingly low incidence of Chinese (24%) and Malays (4%) in the study population, compared to the racial composition of the general clinic population. The age distribution curve of the study population was bimodal with peaks at age groups 21-30 (22%) and 41-60 (33%) years. The most common morphologic variant was lichen planus vulgaris (common type) which we observed in 46 (64%) patients, followed by lichen planus hypertrophicus in 8 (11%) and lichen planus atrophicus in 2 (3%). Lichen planus confined to the skin was observed in 49 (68%) patients. Mucous membrane involvement was seen in 21 (29%)-17 (24%) had oral mucosa membrane involvement and 4 (6%) genital mucous membrane involvement. In 16 (22%) cases, mucous membranes were exclusively involved--12 (17%) had oral mucous membrane involvement and 4 (6%) genital mucous membrane involvement. Nail changes were only observed in 2 (3%) patients. Eight (11%) patients had associated diabetes mellitus. Overall, lichen planus appeared to pursue a protracted course with only 4 (6%) patients clearing completely after a disease duration of 5-12 months.