A Case of Anti-Hu Antibody-positive Paraneoplastic Neurological Syndrome due to Mediastinal Lymph Node Small Cell Carcinoma of Unknown Primary Origin

抄録

A 65-year-old man visited our hospital with the complaint of rapid exacerbation of dysphagia. He had no otolaryngological or digestive system disorders. He was initially suspected to have acute bulbar palsy, a subtype of Guillain-Barré syndrome, and managed accordingly; however, the patient did not respond to treatment. Subsequently, he developed multiple cranial neuropathies and sensory neuronopathy. Additional tests revealed that he had positive anti-Hu antibodies. No obvious mass lesions were noted, but 3 months later, the patient developed enlarged isolated lymph node near the para-aortic lymph nodes. Excision of the focal lymph node revealed small cell carcinoma, without evidence of small cell carcinoma in the lungs. Therefore, the primary lesion was unknown. The patient was diagnosed with paraneoplastic neurological syndrome. In such cases, tumor search often needs to be repeated because neurological symptoms may precede the tumor onset.