A case of eosinophilic gastroenteritis developed during administration of nivolumab for a patient with platinum-resistant head and neck cancer

Eosinophilic gastroenteritis (EGE) is an inflammatory disease that causes symptoms related to dysfunction owing to the high infiltration of eosinophils into the gastrointestinal tissue. We report a case of EGE that developed after severe eosinophilia induced by nivolumab administration. A 53-year-old woman was diagnosed with recurrent neck lymph node metastasis of right tongue cancer and was referred to our hospital for chemotherapy. After the administration of 12 courses of nivolumab, grade 2 diarrhea was observed, and contrast-enhanced computed tomography (CT) revealed intestinal wall edema and stenosis of the small intestine. Symptoms improved with fasting, discontinuation of nivolumab, and administration of a proton pump inhibitor. Biopsy performed using a colon fiberscope revealed EGE. After resuming nivolumab and administering three courses, positron emission tomography/CT confirmed a complete response to the metastatic lesion, and nivolumab was discontinued. After discontinuation, mild eosinophilia persisted, but abdominal symptoms, such as diarrhea, did not recur. No signs of recurrence or metastasis were observed after two years.