Clinicopathological predictors of postoperative long-term myasthenic status in resected thymoma with myasthenia gravis

PurposeSurgical patients with thymoma and myasthenia gravis (MG) must have their MG status and oncological outcomes critically monitored. We aimed to identify clinicopathological predictors of the postoperative MG status.MethodsWe conducted a retrospective review of 40 consecutive surgical patients with MG-related thymomas between 2002 and 2020. The quantitative myasthenia gravis score (QMGS) and Myasthenia Gravis Foundation of America post-intervention status (MGFA-PIS) were used to evaluate postoperative MG status.ResultsAll patients underwent extended total thymectomy. The most common WHO type was type B2 (32%), while 65% of patients had type B1-B3 and 35% had type A-AB thymomas. Eleven patients (28%) achieved controlled MG status in MGFA-PIS 6 months after surgery. This controlled status was observed more frequently in type A-AB than in B1-B3 (57% vs. 12%, p = 0.007). In a multivariate analysis, WHO type (A-AB or B1-B3) was an independent predictor of worsening episodes of MG based on the QMGS (Type B1-B3, hazard ratio: 3.23, 95% confidence interval: 1.12-9.25). At the last follow-up, 23 patients (58%) achieved controlled MG status. The 5-year overall survival rate of all patients was 93.7%.ConclusionThe WHO type of thymoma is an informative predictor of postoperative MG status in patients with MG-related thymoma.