Temporal Association between Thymoma Recurrence and Exacerbation of Myasthenia Gravis

Background: This study investigates the potential link between myasthenia gravis (MG) exacerbation and thymoma recurrence in patients with thymoma-associated MG (TAMG).Methods: We conducted a retrospective medical record analysis at Severance Hospital. Baseline clinical feature of MG, initial histological features, and severity of MG were recorded. Based on the change in MG activities of daily living (ADL) score and MG-spsecific treatments, patients' MG status was assessed over the 2-year period around thymoma recurrence, and was classified into three categories: improved, unchanged, and worse.Results: Of the 178 patients with TAMG, 18 (10.1%) experienced recurrence of thymoma. Mean age at initial thymectomy and at thymoma recurrence was 44.1±9.4 and 48.8±9.1 years, respectively. At the point of thymoma recurrence, myasthenia gravis foundation of America post-intervention status was complete stable remission in four (22.2%), pharmacologic remission in five (27.8%), minimal manifestation in five (27.8%), improved in two (11.1%), and unchanged in two (11.1%) patients. Median MG ADL score was 0.0 (interquartile range [Q1-Q3], 0.0-1.8). During 1-year period before recurrence of thymoma, three patients experienced worsening, probably associated with infection and discontinuation of medication. During the 1-year period after the recurrence, four patients experienced worsening after the second thymectomy.Conclusion: MG worsened in 16.7% and 22.2% of the patients before and after thymoma recurrence, respectively. Exacerbation of MG in cases of thymoma recurrence seems more likely to result from known risk factors, including infection, general anesthesia, or discontinuation of medication, rather than from the recurrence of thymoma itself.