Case Report
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastrointest Endosc. Dec 16, 2013; 5(12): 605-609
Published online Dec 16, 2013. doi: 10.4253/wjge.v5.i12.605
A case of neuroendocrine tumor G1 with unique histopathological growth progress
Misuzu Hirai, Kenshi Matsumoto, Hiroya Ueyama, Hirohumi Fukushima, Takashi Murakami, Hitoshi Sasaki, Akihito Nagahara, Takashi Yao, Sumio Watanabe
Misuzu Hirai, Kenshi Matsumoto, Hiroya Ueyama, Hirohumi Fukushima, Takashi Murakami, Hitoshi Sasaki, Akihito Nagahara, Sumio Watanabe, Department of Gastroenterology, Juntendo University, School of Medicine, Tokyo 113-8421, Japan
Takashi Yao, Department of Human Pathology, Juntendo University, School of Medicine, Tokyo, 113-8421, Japan
Author contributions: Hirai M wrote the manuscript; Matsumoto K, Ueyama H and Nagahara A diagnosed and treated; Fukushima H and Sasaki H performed endoscopic ultrasound; Murakami T and Yao T contributed to the histopathological diagnosis; Watanabe S revised the manuscript; all authors discussed the results and commented on the manuscript; and Watanabe S gave final approval of this article.
Correspondence to: Kenshi Matsumoto, MD, PhD, Department of Gastroenterology, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. kmatumo@juntendo.ac.jp
Telephone: +81-3-38133111 Fax: +81-3-38138862
Received: October 24, 2013
Revised: November 20, 2013
Accepted: December 9, 2013
Published online: December 16, 2013
Abstract

A gastric neuroendocrine tumor (NET) is generated from deep within the tissue mucosal layers. In many cases, NETs are discovered as submucosal tumor (SMT)-like structures by forming a tumor mass. This case has a clear mucosal demarcation line and developed like a polyp. A dilated blood vessel was found on the surface. The mass lacked the yellow color characteristic of NETs, and a SMT-like form was evident. Therefore, a nonspecific epithelial lesion was suspected and we performed endoscopy with magnifying narrow-band imaging (M-NBI). However, this approach did not lead to the diagnosis, as we diagnosed the lesion as a NET by biopsy examination. The lesion was excised by endoscopic submucosal dissection. The histopathological examination proved that the lesion was a polypoid lesion although it was also a NET because the tumor cells extended upward through the normal gland ducts scatteredly. To our knowledge, there is no previous report of NET G1 with such unique histopathological growth progress and macroscopic appearance shown by detailed examination using endoscopy with M-NBI.

Keywords: Neuroendocrine tumor G1, Demarcation line, Polypoid growth, Magnifying narrow-band imaging, Submucosal tumor

Core tip: Neuroendocrine tumors which infiltrate into the mucosa may develop a polypoid appearance mimicking a primary epithelial process.