Gastric Mixed Adenoneuroendocrine Carcinoma Occurring 50 Years after a Gastroenterostomy with Braun Anastomosis

A 75-year-old man was diagnosed with gastric cancer. Fifty years previously, he had undergone gastroenterostomy with a Braun enteroenterostomy. At present, a distal gastrectomy and small intestinal partial resection were performed. Intraoperatively, the tumor was localized to the previous stomal site. HE staining showed that the tumor comprised two elements: a tubular adenocarcinoma on the gastric side and a neuroendocrine carcinoma (NEC) on the jejunal side. The final pathologic diagnosis was mixed adenoneuroendocrine carcinoma based on an immunohistochemical analysis of endocrine markers and an elevated Ki-67 labeling index. The risk of later cancer development cancer recurrence near the gastrojejunostomy site is well known. Potentially, chronic enterogastric bile reflux may irritate the gastric mucosa and act as a promoter. Gastric NEC has a strong malignant potential. We suspect that, in the present case, the constant exposure to secondary bile may have induced a gastric mucosal adenocarcinoma, which finally differentiated into a NEC.