2019 Volume 61 Issue 12 Pages 2604-2609
Mixed adenoneuroendocrine carcinoma (MANEC) is a complex form of neuroendocrine carcinoma (NEC) and adenocarcinoma, and early-stage MANEC is rarely found by endoscopy. An 80-year-old man with a past history of gastric ulcer on the posterior wall of the gastric corpus underwent follow-up esophagogastroduodenoscopy (EGD). EGD revealed a depressed region in the greater curvature of the gastric angle. Biopsy led to the diagnosis of moderately-differentiated tubular adenocarcinoma. We established the diagnosis of intra-mucosal gastric cancer and performed endoscopic submucosal dissection (ESD). During ESD, a discolored region contiguous with the depressed region was noted. Narrow-band imaging with magnification indicated that a surface pattern was absent and an irregular microvascular pattern with high density was present in the depressed region. The discolored region had an irregular and papillary surface pattern with sparse microvasculature. Histopathological examination of the ESD-resected specimen revealed large-cell NEC in the depressed region and well-differentiated adenocarcinoma in the discolored region. The patient was diagnosed with MANEC. In this case, we correlated the endoscopic and pathological findings and diagnosed NEC given the absence of a surface pattern within the depression and the presence of a well-differentiated tubular adenocarcinoma in the continuous papillary structure. Thus, our case illustrates the diagnostic procedure of MANEC on endoscopic observation.
