[Post-thymectomy Myasthenia Gravis ; Report of a Case].

A 46-year-old woman was referred to our hospital for a tumor in the anterior mediastinum. She had no symptoms of myasthenia gravis(MG). Acetylcholine receptor antibody(AchR-Ab) was within the normal range. The tumor was completely resected by thymectomy. Pathological examination of the tumor identified it as a type AB thymoma (Masaoka stage I). Five days after the surgery, she experienced post-thymectomy MG (raised AchR-Ab and positive tensilon test). Her symptoms improved with anti-cholinesterase and tacrolimus therapy.