A Case of Unicentric Castleman Disease with Concomitant Myasthenia Gravis and Persistent Left Superior Vena Cava

BACKGROUND Castleman disease was first described in 1956 as mediastinal masses composed of benign lymphoid hyperplasia with germinal center formation and capillary proliferation closely resembling thymomas. It has been linked with many multi-system disorders, including myasthenia gravis. Cases of Castleman disease with corresponding myasthenia gravis have higher rates of postoperative myasthenic crisis, which are reported as high as 37.5%. We encountered a case of Castleman disease with myasthenia gravis that was discovered early and managed successfully with complete surgical resection and no postoperative myasthenic crisis. CASE REPORT A 25-year-old woman with an uncomplicated history presented with shortness of breath, numbness in hands, tiring with chewing, and fatigue. Myasthenia gravis was diagnosed with serology test results, and a 7.5×7.0-cm mediastinal mass was discovered in addition to the incidental finding of a persistent left superior vena cava, closely abutting the mass. Biopsy showed lymphoid proliferation, regressed germinal centers surrounded by small lymphocytes, and vascular proliferation, consistent with unicentric Castleman disease, hyaline-vascular type. The patient was successfully treated for Castleman disease with myasthenia gravis, and no postoperative myasthenic crisis occurred. CONCLUSIONS Castleman disease associated with myasthenia gravis can dramatically increase the risk of postoperative myasthenic crisis. Our literature review of all 16 cases of Castleman disease with myasthenia gravis since 1973 revealed that 18.75% of cases were associated with a postoperative myasthenic crisis. This association elicits the importance of prompt diagnosis of myasthenia gravis when evaluating mediastinal masses and the value of having neurology and anesthesiology staff aware of the increased risk of crisis.