[Small thymolipoma in association with myasthenia gravis].

A 40-year-old woman was admitted with diplopia and muscle weakness. A diagnosis of myasthenia gravis was made. Chest radiographs and chest CT showed no mediastinal abnormality. Extended thymectomy was performed. Small tumor (2 X 1 X 0.5 cm) was found within the thymic tissue. Histological examination revealed that the tumor was composed with mature adipose tissue, which expanded and compressed the thymic tissue. The histological appearances were considered to be a typical thymolipoma. This case is the sixth in the world literature in which a thymolipoma is associated with symptoms of myasthenia gravis, and the size of tumor is smallest in the reported cases.