Thymoma and myasthenia gravis - an observational study at a tertiary center

Acquired Myasthenia Gravis (MG) is a rare autoimmune neurological disorder characterized by fluctu- ating paresis of the skeletal muscle due to pathogenic antibodies against the acetylcholine receptor or other elements of the neuromuscular plaque. There is a close relation between MG and thymoma. We aimed to characterize a population of patients with Myasthenia Gravis associated thymoma (MGAT).

Retrospective and longitudinal study in all patients with MGAT observed at a tertiary center between 2009 and 2020. We assessed epidemiological, clinical, laboratory and therapeutic features of both MG and thymoma.

We found 18 patients with an average age of 53 ± 16.2, 13 of them females. Most patients (n=15) presented the generalized MG form. Most frequent Masaoka staging was II (n=7). Regarding the WHO histopathological classification of thymoma, most patients (n=11) presented with type B2 or B3. Thirteen patients underwent extended thymectomy (12 by median sternotomy and 1 by VATS). Of the remaining 5 patients, 4 of them underwent a CT scan guided biopsy, and 1 patient did not accept further work-up. Seven patients were classified as R0 for surgical resection margins and only one of them had recurrence of thymoma. Besides surgery, oncological treatment included radiotherapy and chemotherapy. Five patients expe- rienced a myasthenic crisis during the course of the disease. Three deaths occurred in the studied population.

This study helped to pinpoint important aspects concerning therapeutic orientation of MGAT patients, such as the clinical impact of thymectomy in the course of MGAT, the oncological prognostic value of surgical resection mar- gins, and the importance of preoperative intravenous immunoglobulin. Management of MGAT patients is only possible with a multidisciplinary approach.