ObjectiveTo compare clinical effects of extended thymectomy for the treatment of thymic abnormalities with myasthenia gravis (MG) between subxiphoid and subcostal arch thoracoscopic resection (SR) and the unilateral thoracoscopic resection (UR) by a propensity-score matching analysis.MethodsWe retrospectively analyzed the clinical data of 612 patients who presented with MG and were admitted to Tangdu Hospital of Air Force Military Medical University between December 2011 and December 2018. Of these patients, 520 patients underwent subxiphoid and subcostal arch thoracoscopic extended thymectomy (a SR group) and 92 unilateral thoracoscopic extended thymectomy (a UR group). Ninety-two patients in the SR group were matched with the UR group by propensity-score matching analysis. There were 52 males and 40 females with an average age of 26-70 (50.2±10.3) years in the SR group, and 47 males and 45 females with an average age of 20-73 (51.5±12.1) years in the UR group. The operation time, intraoperative blood loss, thoracic drainage time, postoperative hospital stay, thorough adipose tissue removal, postoperative remission of MG, patients’ satisfaction score, pain and complications were compared and analyzed between the two groups.ResultsAll operations were accomplished successfully, without conversion to thoracotomy of the two groups. There were statistical differences between the two groups in operation time (46.2±19.5 min vs. 53.4±23.5 min), chest drainage duration (0 d vs. 3.4±1.2 d), hospital stay (2.9±1.9 d vs. 3.6±1.7 d), patients’ satisfaction score (7.9±2.1 points vs. 6.7±1.2 points) and pain scores (all P<0.05). There were no statistical differences between the two groups in intraoperative blood loss (52.2±12.7 mL vs. 51.2±10.3 mL), peripheral adipose tissue removal (8.1±0.6 vs. 7.9±0.9), remission rate of MG (89.1% vs. 85.9%) and rate of postoperative complications (10.9% vs. 6.5%) (all P>0.05). ConclusionSubxiphoid and subcostal arch thoracoscopic extended thymectomy is a safe and feasible minimally invasive procedure for the management of MG with thymic abnormalities.