A case of small intestinal neuroendocrine carcinoma diagnosed using double-balloon endoscopy with long-term survival.

Neuroendocrine neoplasms, including neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs), are rare epithelial tumors with a predominant neuroendocrine differentiation. Compared with NETs, NECs have been reported to be rarer and have a poorer prognosis. We present a rare case of small bowel NEC diagnosed using double-balloon endoscopy (DBE) and the long-term survival accomplished via intensive therapy. DBE revealed an ulcerative tumor in the deep jejunum, and biopsy specimens showed large and highly dysplastic tumor cells; immuno-histological synaptophysin and chromogranin A tests were positive, and the Ki-67 index was more than 90%. Partial intestinal resection without complete lymph node dissection was performed and, postoperatively, chemotherapy was administered. The patient was observed for 3 years after chemotherapy, and complete remission was maintained.