Synchronous multiple thymoma: report of three cases.

We report three cases of synchronous multiple thymoma diagnosed at a single hospital during the 10 years since 1999. Two were accompanied by myasthenia gravis (MG). In two patients, two thymomas were detected by preoperative computed tomography (CT), and in one, a microthymoma was found incidentally on pathologic examination of a resected specimen for gross thymoma and thymus. The multiple lesions were located in the thymus, and extended thymectomy was performed via median sternotomy in all three patients. The World Health Organization subtypes of the multiple thymomas were identical in each patient; however, all were considered to be primary lesions since the larger one was well encapsulated and each tumor was apparently separated. The Masaoka stage was classified as I/I, I/I, and I/II, respectively. Postoperative clinical courses were uneventful and no recurrence was observed in any of the patients. We reviewed 16 reported cases of synchronous multiple thymoma, and discuss the pathogenesis and treatment of this unusual entity.