Muscular pathological features in patients with myasthenia gravis.

Objective To analyze muscle histopathology of myasthenia gravis (MG) patients and further explore the underlying mechanism comparing with previous literature. Materials and methods We analyzed the clinicopathological features of 8 MG patients who had muscle biopsy examinations. Results Eight patients with a diagnosis of MG were retrospectively recruited from the Chinese PLA General Hospital. One patient had positive anti-MuSK antibodies, 5 patients had positive anti-AChR antibodies (1 of whom had additional positive anti-Titin antibodies), and 2 patients were seronegative. Seronegative-MG presented normal muscle histology, occasionally with lipid deposition. Small angular atrophy (mainly in type II fibers) and necrosis in H & E stain were found in AChR-MG, furthermore, patterns of polymyositis (PM) could be found in AChR-MG with anti-Titin antibodies. Mitochondrial abnormalities were found only in MuSK-MG. Conclusion Muscle histological abnormalities mimicking myopathy may be found in MG patients. Patients with different antibodies present with different muscle histopathology. PM pattern pathology is a special pattern of muscle histology in MG that should not be misdiagnosed. Our study has extended the muscle pathological features of MG in addition to deepening the understanding of MG.