Spontaneous remission of myasthenia gravis in patients with thymoma

In 42 cases of myasthenia gravis with thymoma, the tumor was removed surgically. In four of these cases, myasthenic symptoms had remitted before operation. However, in two of these four cases, myasthenic symptoms returned after operation, despite apparently total thymectomy. In two of the four cases that remitted before operation, the thymus was found to be highly involuted, without germinal centers; in another case, the thymus was found to be moderately involuted, and germinal centers were found. In the nonrelapsing cases, only the tumor itself was removed, with residual thymic tissue being left behind. The thymoma in all cases consisted of polygonal epithelial cells and lymphocytes.