Large-cell neuroendocrine carcinoma arising from a gastritis cystica polyposa.

Gastritis cystica polyposa is a polypoid lesion that arises from the gastric mucosa at the gastrojejunal anastomotic site and is characterized by cystic dilation of the gastric glands. A 78-year-old man who underwent distal gastrectomy for a gastric ulcer with Billroth II reconstruction approximately 40 years previously, exhibited a gastritis cystica polyposa at the anastomotic site. Ulceration was observed on an annual endoscopic examination. Endoscopic ultrasonography revealed a submucosal hypoechoic mass with multiple cystic lesions. Gastrectomy was performed and histological examination revealed a large-cell neuroendocrine carcinoma with cystic dilation of the gastric glands. Here, we report the first case of a large-cell neuroendocrine carcinoma arising from a gastritis cystica polyposa. Endoscopic ultrasonography was effective at diagnosing a submucosal hypoechoic mass with cystic dilation of the gastric glands.