The literature on lichen planus is large but, except for a very few phases, the entire condition is still open to discussion. The papers by Little and White read before the American Dermatological Association and the discussion which followed included the opinions of many dermatologists on this condition. All agreed as to its typical histologic picture and its usually typical but sometimes multiform clinical manifestations. This multiformity was well demonstrated by Fordyce and MacKee in a series of photographs and in their accompanying discussion. The etiology, symptoms, course and treatment of lichen planus has caused much and diverse comment. Starting with the early writers we find controversy as to whether its cause is microbic or neurotic. Most of these believed in the neurotic etiology though the histologic picture led some to infer it was infective. Lassar claimed to have demonstrated a bacillus in the lymph spaces of the corium, but