A Case of Intramucosal Gastric Cancer Partly Containing Poorly Differentiated Adenocarcinoma Component with Neuroendocrine Features

Abstract

An 81-year-old man underwent esophagogastroduodenoscopy, and a 30-mm elevated-type lesion was identified at the greater curvature of the lower gastric body. There were no signs of submucosal invasion. Biopsy specimens revealed moderately differentiated adenocarcinoma, and endoscopic submucosal resection was performed. Pathological examination revealed moderately differentiated adenocarcinoma with a small component of poorly differentiated adenocarcinoma. Immunohistological examination of the component showed synaptophysin (−) ,chromogranin A (−) and CD56 (＋) . Ki-67 was positive in ＞ 90% of the cells. The final histopathological diagnosis was Type0-I＋IIa, 29×21 mm, pap＞ tube1, tub2 ＞＞ por1 with neuroendocrine features : pT1a, ly0, v0, pHM0, pVM0. This case may be an initial stage of neuroendocrine carcinoma, and therefore valuable in revealing the development and prognosis of similar cases.