Post-thymectomy myasthenia gravis with an episode of Osserman stage III

Here, we present the first case of post-thymectomy Myasthenia Gravis with onset at Osserman stage III. An 81-year-old woman was admitted for an abnormal shadow seen in a chest radiograph. She had no symptoms of Myasthenia Gravis. Acetylcholine receptor antibody was within the normal range. Chest computed tomography (CT) showed a bulky anterior mediastinal tumor. She was diagnosed as having thymoma by tissue biopsy under CT guidance. The tumor was completely resected by performing thymothymectomy, left upper lobectomy, pericardial resection, and phrenicectomy. Pathological examination of the tumor identified it as a thymoma (type B2, Masaoka stage II). Two months after the surgery, she experienced the onset of post-thymectomy myasthenia gravis with Osserman stage III. The acetylcholine receptor antibody level was remarkably elevated (220 nmol/L); however, there was no evidence of tumor recurrence.