Lichen planus: a theory of pathogenesis.

From a continuing study of 108 cases of oral mucosal lichen planus, including so-called drug-induced lichenoid reactions, the response of patients to topical therapy and to drugs implicated in inducing the lichenoid reactions was used to construct a hypothetical model regarding the pathogenesis of the condition. The results were interpreted to indicate that lichen planus is a predetermined condition or diathesis, perhaps genetically based, rather than a simple cause-and-effect disorder.