Abstract
A 52-year-old man with the complaint of increasing weakness of leg muscular strength and difficulty of focusing was admitted to our institute for treatment. He had ptosis of the eyelids, but no dyspnea or dysphagia. The neurological first diagnosis was myasthenia gravis. Repetitive nerve stimulation showed a typical waning pattern at 3 Hz and 5Hz, but and acetylcholine receptor antibodies and anti muscle-specific receptor tyrosine kinase antibodies were both within normal limits. A chest CT showed paratracheal lymph node swelling, but, revealed no abnormal findings in the lung field. Pro-GRP in the blood was slightly high, while other tumor markers including NSE were within normal limits. The paratracheal lymph node was resected under VATS with thymic carcimona considered from the biopsy in the operation room. VATS was switched to a median sternotomy because of the biopsy results, and extensive thymectomy and resection of the mediastinal lymph nodes were performed. After the operation, immunohistopathological findings revealed lymph node small cell carcinoma with no apparent primary lesion. His postoperative course was uneventful. He left our institute 45 days after the operation. Anti voltage gated calcium channel antibodies in the blood were very high before and after the operation. At this time, he was diagnosed with Lambert-Eaton myasthenic syndrome. He became an outpatient for 3 months, with general fatigue and weakness of muscular strength gradually increasing. Pro-GRP increased again, and he was admitted to the hospital again for chemotherapy with CBDCA and irradiation therapy. Pro-GRP decreased to within normal limits after the treatment; however, he still complained of fatigue and reduced muscular strength. He must be followed up carefully, because primary lesions of small cell carcinoma will often appear.
