Myasthenia gravis and invasive thymoma: a 20-year experience.

In 20 years, 19 patients with myasthenia gravis and invasive thymoma have been seen by the Neurology Service at the UCLA Center for Health Sciences. This represents 4 percent of 493 myasthenia gravis patients seen during the same time and 37 percent of myasthenic patients with thymomas. Eight are still alive and 11 have died. Fifteen patients had the onset of myasthenic symptoms before discovery of the thymoma, while only four patients had chest symptoms and/or radiographic evidence of an anterior mediastinal mass prior to the onset of weakness. Radical excision of the tumor, if possible, and the remaining thymus, high dosage alternate day prednisone, and radiation therapy, if indicated, seem the treatments of choice. Recurrences of tumor nodules may necessitate further local radiation or the use of cytotoxic agents.