[Results and problems of thymectomy in myasthenia gravis over 65 years old]

From June 1975 to March 1999, 300 cases of myasthenia gravis (MG) have undergone thymectomy. Twenty-eight patients over 65 years old were examined, focusing on the relationship between clinical appearances and microscopic findings of the thymuses. Among these cases, six were classified as ocular type (one case with thymoma) and 22 generalized type (eight cases with thymoma). According to the thymoma registering stages defined by Masaoka and colleagues, those nine cases with thymoma associated with stages I (n = 7), II (n = 1) and III (n = 1), respectively. The case of stage III (74 year old female) died four years and eight months after surgery. The case of stage II died of old age two years after the surgery. Complete remission was achieved in two cases of stage I. The follicular hyperplasia were seen in eight cases, and all resulted in improvement. Nine cases with no particular findings of thymuses classified into four ocular type and five generalized type including one fulminating type. Post-operative course of all these cases were uneventful. Although one recurrent of the thymoma and one death of the tumor were observed, post-operative outcomes of these elderly patients were generally satisfactory. We concluded that there is an operative indication of thymectomy for MG of even elderly patients, if no particular findings were recognized in the thymus.