MGAM and myasthenia gravis: Compared to MG-positive patients, MG-negative patients had significantly higher preoperative Fibrinogen serum concentrations (404.9 ± 124.4 mg/dL vs. 351.8 ± 102.3 mg/dL; p = 0.037) and tumor size (6.1 ± 3.1 cm vs. 4.5 ± 2.9 cm; p = 0.049).