Case Report
Copyright ©2014 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 21, 2014; 20(19): 5918-5923
Published online May 21, 2014. doi: 10.3748/wjg.v20.i19.5918
Two rare gastric hamartomatous inverted polyp cases suggest the pathogenesis of growth
Hirohito Mori, Hideki Kobara, Takaaki Tsushimi, Shintaro Fujihara, Noriko Nishiyama, Tae Matsunaga, Maki Ayaki, Tatsuo Yachida, Tsutomu Masaki
Hirohito Mori, Hideki Kobara, Shintaro Fujihara, Noriko Nishiyama, Tae Matsunaga, Maki Ayaki, Tatsuo Yachida, Tsutomu Masaki, Department of Gastroenterology and Neurology, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kita, Kagawa 761-0793, Japan
Hirohito Mori, Takaaki Tsushimi, Department of Gastroenterological Surgery, Ehime Rosai Hospital, 13-27, Minamikomatsubara, Niihama, Ehime 792-8550, Japan
Author contributions: Mori H was responsible for devising the research and writing the manuscript; Kobara H, Tsushimi T, Fujihara S, Nishiyama N, Matsunaga T, Ayaki M and Yachida T participated equally in the work; Masaki T provided a critical revision of the manuscript for intellectual content and was responsible for the final approval of the manuscript.
Correspondence to: Hirohito Mori, MD, PhD, Department of Gastroenterology and Neurology, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kita, Kagawa 761-0793, Japan. hiro4884@med.kagawa-u.ac.jp
Telephone: +81-87-8912156 Fax: +81-87-8912158
Received: November 25, 2013
Revised: December 27, 2013
Accepted: March 4, 2014
Published online: May 21, 2014
Abstract

Gastric hamartomatous inverted polyps (GHIP) are difficult to diagnose accurately because of inversion into the submucosal layer. GHIP are diagnosed using the pathological characteristics of the tumor, including the fibroblast cells, smooth muscle, nerve components, glandular hyperplasia, and cystic gland dilatation. Although Peutz-Jeghers syndrome, juvenile polyposis, and Cowden disease are hereditary, it is rare to encounter 2 cases of monostotic and asymptomatic gastric hamartomas. The pathogeneses of hamartomatous inverted polyps and inverted hyperplastic polyps remain controversial because of the paucity of reported cases. There are 3 hypotheses regarding the pathogenesis of complete gastric inverted polyps. Based on our experience with 2 successive, rare GHIP cases, we affirm the hypothesis that after a hamartomatous change occurs in the submucosal layer, some of these components are exposed to the gastric mucosa and, consequently, form a hypertrophic lesion. In Case 1, our hypothesis explains why a tiny hypertrophic change was first detected on the top of the submucosal tumor using a detailed narrow band imaging-magnified endoscopy. There was no confirmation that the milky white mucous and calcification structures were exuding directly from the biopsy site like Case 1, and in Case 2 the presence of this mucous was indirectly confirmed during an endoscopic submucosal dissection (ESD). Regarding the pathogenesis of GHIP, a submucosal hamartomatous change may occur prior to the growth of hypertrophic portions. An en bloc resection using ESD is recommended for treatment.

Keywords: Hamartomatous inverted polyps, Hypotheses of pathogenesis, Milky white mucous, Endoscopic submucosal dissection, Pathological findings

Core tip: The pathogeneses of hamartomatous inverted polyps (HIP) and inverted hyperplastic polyps remain controversial. Our experience with 2 rare successive cases of HIP suggests that after a hamartomatous change occurs in the submucosal layer, some of these components are exposed to the gastric mucosa and, consequently, form a hypertrophic lesion. An en bloc resection by endoscopic submucosal dissection is recommended for treatment.