Paraneoplastic neurological syndrome in a patient with gastric cancer

Paraneoplastic neurological syndromes (PNSs) are a heterogeneous group of neurological disorders caused by immune-mediated mechanisms. The incidence of PNS is much less than 1% for solid tumors, except for small-cell lung cancer and thymoma. We report a rare case of gastric cancer that presented with primary clinical findings of PNS. The patient was a 63-year-old woman who was admitted for worsening neuropathy. Laboratory and neurological tests excluded a nutritional deficit, diabetes mellitus, and connective tissue disease as causes of her neuropathy. Computed tomography (CT) of the abdomen, positron emission tomography (PET)-CT, and endoscopy of the stomach revealed gastric cancer with lymph node swelling. Distal gastrectomy was performed and pathological and immunohistochemical examinations indicated endocrine cell carcinoma. The gastrectomy stopped the exacerbation of her symptoms and recurrence was not observed, but the neurological disorders were irreversible. This case suggests that early diagnosis of the primary tumor is required to improve the outcome in patients with PNS.