Familial lichen planus.

We observed the simultaneous occurrence of generalized lichen planus in a woman and her mother. Both patients improved after therapy with topical steroid and salicylic acid ointment. Of the eighty-one cases of familial lichen planus previously reported, the vast majority (89 percent) occurred in blood relatives. The intervals of onset between familial cases were long, ranging from six weeks to thirty years (mean 73.4 months). These observations suggest that familial lichen planus may result from genetic predisposition, rather than from an infectious cause.