Thymolipoma and its Association with Myasthenia Gravis: a Multi-center Experience

BACKGROUND: Thymolipoma is a rare benign thymic tumor that arises in the anterior mediastinum. It presents with non-specific symptoms such as chest pain and dyspnea due to compression of the tumor on surrounding structures. In addition, this tumor is associated with paraneoplastic syndromes, including myasthenia gravis. Such a relationship is still not understood and requires investigation. OBJECTIVE: Investigate the significance of myasthenia gravis in thymolipoma patients. METHODS: We present a series of 16 thymolipoma cases from multiple medical centers. Data extraction included demographic, diagnostic, radiological and laboratory, and clinical outcome variables. We also used the modified Osserman score to assess the severity of myasthenia gravis. RESULTS: Ten patients were males, and six were females; the sample mean age was 39.9 years (SD = 16.7). Upon presentation, 7/16 patients were asymptomatic, 4/16 patients had chest pain, and 2/16 had dyspnea. Seven patients were having myasthenia gravis; they experience generalized weakness (3/7), diplopia (2/7), ptosis (1/7), and bulbar weakness (1/7). Serum acetylcholine receptor antibody (AChRAb) was positive in 4 patients. All patients underwent thymectomy either via sternotomy or thoracotomy. After proper follow-up, only 2/7 of myasthenic patients had a complete remission of symptoms, no tumor recurrence was observed. CONCLUSION: Although the effect of using steroids in myasthenic patients on thymolipomic transformation still needs confirmation, diagnosis of thymolipoma should be kept in mind in myasthenic patients presenting with relevant symptoms and taking steroids. Furthermore, complete remission of myasthenic symptoms after removal of thymolipoma needs further investigation.