[Clinical analysis of myasthenia gravis accompanied by invasive thymoma]

Abstract

Over the last 20 years, 6 patients with myasthenia gravis and invasive thymoma have been seen in our Department. These patients underwent non-total excision cases. This represents 2.5 percent of 242 myasthenia gravis patients in our series. We can see 17 such patients in the literature in Japan including our cases. The age ranged 20 to 77 years and the ratio of male to female was 10:7. Post-operative therapeutic methods for invasive thymoma included irradiation, steroid therapy and combination chemotherapy. Every method showed good therapeutic results, but steroid therapy and chemotherapy showed especially good therapeutic effects in the early stage of the disease. Though these therapeutic effects were better than those obtained in other malignant tumors, thymomas tended to reappear within several years, when tumors showed no response to any therapeutic method. It is well known that steroid therapy reduces the level of antiacetylcholine receptor antibody, whereas chemotherapy also reduces antiacetylcholine receptor antibody. Over all 5-year survival rate was 53%, and the 10-year survival rate was 29%. Three out of 6 cases of death were due to myasthenic crisis (50%) and 2 out of 6 cases were due to invasive tumor itself (38%). These results suggested that total excision of the thymoma, if possible, and for the remaining tumor, high doses of adrenocorticosteroids and combination chemotherapy seem to be treatments of choice.