Seropositive Myasthenia Gravis Associated with Small-Cell Lung Carcinoma

BACKGROUND: Lambert-Eaton myasthenic syndrome is well known to be a classical paraneoplastic syndrome of small cell lung carcinoma (SCLC). Three cases of seronegative myasthenia gravis (MG) and SCLC were previously reported. CASE REPORT: A 65-year-old man developed a severe progressive respiratory failure with clinical features of MG. Tests showed a decremental response in the repetitive nerve stimulation test, abnormal single-fiber electromyography, and positive acetylcholine receptor antibody. SCLC was confirmed by the lung biopsy. CONCLUSIONS: This case represents the first case of seropositive MG and SCLC.