[A patient of myasthenia gravis complicated by lichen planus 9 years after thymectomy].

We report a 39-year-old woman with myasthenia gravis (MG) complicated by lichen planus, elevated liver enzymes of unknown cause and mucosal lesions of the colon and anus. Although the etiology of lichen planus is uncertain, an autoimmune abnormality is considered to be a possible cause. Lichen planus is sometimes associated with thymoma. This patient had hyperplasia of the thymus which was surgically removed nine years prior to lichen planus development. Myasthenic symptoms worsened when the lichen planus appeared and the liver enzymes were elevated. Steroid therapy was effective for the above symptoms. The clinical course suggests that MG, lichen planus and elevated liver enzymes in this patient results from common underlying autoimmune abnormality.