[A patient with intractable myasthenia gravis successfully treated with total lymphoid irradiation]

We report a 20-year-old man with intractable myasthenia gravis successfully treated with total lymphoid irradiation (TLI). An encapsulated thymoma in the anterior mediastinum was resected as extended thymectomy by video-assisted thoracoscopic surgery at 2 months after the onset of ptosis and muscle weakness. Following treatments, such as ambenonium hydrochloride, an immunosuppression therapy (prednisolone and azatioprine), 5 courses of immunoadsorption therapy, and a high dose of cyclophosphamide and methylprednisolone, did not make persistent improvement of myasthenic symptoms. Ageusia occurred twice prior to myasthenic crises and subsided with other myasthenic symptoms after treatments. Steroid psychosis and secondary Cushing's syndrome made us to reduce the dose of prednisolone. Post-operative residual, recurrent, or metastatic thymus was not unveiled, then we added the low dose fractionated irradiation (1.5 Gy x 12 = 18 Gy) to the mediastinum. Three months after the irradiation, however, a crisis occurred and the titer of anti-acetylcholine receptor antibody increased up to 100 nmol/l. Therefore, we performed TLI (Mantle; 1.5 Gy x 9 = 13.5 Gy, paraaortic and inverted-Y; 1.5 Gy x 14 = 21 Gy), which brought about persistent improvement of myasthenic symptoms with decrease in the titer of anti-acetylcholine receptor antibody.