LAUSR

Abstract Thymoma is one of the most common anterior mediastinal tumors in adults. The wide range of paraneoplastic syndromes associated with thymoma has been reported. There are few reported cases of thymoma associated with neuromyelitis optica spectrum disorder (NMOSD). We reported a 52-year-old man who was diagnosed with thymoma type B2 but loss follow-up. After 1 year, he developed subacute ascending paraparesis, bowel-bladder involvement without chest symptoms. The spinal cord syndrome was suspected from physical examination. The whole spine MRI showed multifocal short and long segments of hyperintense T2 lesion in C3/4, C5-1, T6-8, T10 levels. The cerebrospinal fluid revealed aseptic meningitis (WBC 100, lymphocyte 99%, neutrophil 1%, protein 60.8 mg/dL, normal glucose level) and negative for culture or PCR for viruses. The CSF aquaporin-4 were negative. However, the CSF paraneoplastic panel showed a positive for anti-titin. The brain MRI revealed an inhomogeneous isointense T2/FLAIR 1.7 x 2.2 cm at the left temporal lobe. The biopsy of temporal lesion reported as demyelinating disease. The NMOSD with the serology negative was diagnosed. He was treated with 5 days of intravenous methylprednisolone (1 gm/day) but his motor power was not improved. The plasmapheresis was initiated for 5 days. There was minimal improvement but his motor weakness worsened again. The multi-disciplinary team decided to treat underlying thymoma with chemotherapy. CAP regimen (cyclophosphamide 500 mg/m2, adriamycin 50 mg/m2 and paclitaxel 50 mg/m2) was administrated every 3 week for 4 cycles. His motor power and bowel-bladder function were gradually improved to full recovery. His chest CT showed decrease size of the thymoma. Thymoma could be associated with NMOSD. The treatment of thymoma should be considered to improve the neurological symptoms.