Examination On The Necessity Of Pericardial Fat Tissue Resection In Extended Thymectomy For Myasthenia Gravis

Background: Extended thymectomy with pericardial fat tissue resection has been a mainstay in the treatment for myasthenia gravies (MG), but few studies have examined the necessity of the pericardial fat tissue resection in extended thymectomy.Methods: We pathologically examined the distribution of germinal centers in the resected thymus including the thymus-surrounding fat tissue. Patients who underwent extended thymectomy using subxiphoid thoracoscopy for generalized MG or thymoma with anti-acetylcholine receptor antibody (anti-AchR Ab) positivity from March 2015 to January 2021 were included in this study.Results: A total of 20 patients underwent extended thymectomy (generalized nonthymomatous MG, n=5; generalized MG with thymoma, n=6; thymoma with anti-AchR Ab positivity, n=9). The resected specimens were divided to 6 parts and were pathologically examined to investigate the distribution of the geminal centers in all lesions. The number and distribution of germinal centers in the thymus varied depending on the patient, and no germinal centers were identified in the right or left pericardial fat tissues.Conclusions: It is necessary to resect the pericardial fat tissue in patients whose preoperative images show the presence of pericardial fat tissue hyperplasia or ectopic thymoma. However, extensive pericardial fat tissue resection might not be necessary for all MG patients who undergo extended thymectomy with opening of the bilateral pleural by video-assisted or robot-assisted thoracoscopic surgery (RATS) via a subxiphoid approach.