[A case report of extended thymectomy in an elderly patient with myasthenia gravis associated with Hashimoto's disease].

We experienced a case of late-onset myasthenia gravis associated with Hashimoto's disease. A 74-year-old female with chief complaints of extremities acratia and hypohidrosis was diagnosed as having myasthenia gravis by the Tensilon test. In addition severe hypothyroidism was noted, and histological examination of a thyroid biopsy revealed Hashimoto's thyroiditis. Extended thymectomy was carried out, and the postoperative course was uneventful due to administration of an anti-ChE drug and a thyroid hormone. This case is extremely rare because only 10 patients with late-onset (over 70 years old) myasthenia gravis have been reported in the literature in Japan, and only three of them were associated with Hashimoto's disease. It was suggested that, in cases of myasthenia gravis in elderly patients, we should take into consideration radical therapy including thymectomy as a positive approach to treatment.