Myasthenia gravis and lymphoblastic lymphoma involving the thymus: A rare association

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disease. An association between thymic epithelial neoplasms and MG is well known. Howev er, it is rarely associated with hematologic malignancies. In particular, v ery few cases of lymphoblastic lymphoma involving the thymus and MG have be en reported. Here we report a case T-cell lymphoblastic lymphoma involving the thymus who developed MG after the initial diagnosis. The patient initia lly presented with a mediastinal mass which was diagnosed as lymphoblastic lymphoma. MG was diagnosed during leukemic relapse in this patient and was based on clinical presentation and neurophysiologic studies including singl e fiber electromyography (EMG) and repetitive nerve stimulation tests. In c ontrast to the other cases with such an association, the myasthenic symptom s presented nine months after the diagnosis of lymphoma by thymectomy. The patient had a highly aggressive clinical course and was resistant to variou s chemotherapy regimens.