Multifocal Adenocarcinomas Arising within a Gastric Inverted Hyperplastic Polyp

Abstract

We present herein the occurrence of multifocal adenocarcinomas with a minute signet ring cell carcinoma that arose within a gastric inverted hyperplastic polyp (IHP) in a 40-year-old woman. Endoscopic ultrasonography demonstrated a heterogeneous hypoechoic mass in the third layer of the gastric wall. The endoscopic submucosal dissection specimen measuring 3.5×3.2×1.8 cm was a well-circumscribed protruding lesion that had a slit-shaped cavity. Histologically, the lesion consisted mainly of endophytic proliferation of hyperplastic columnar cells resembling normal foveolar epithelium. In addition, six foci of adenocarcinomas and a minute focus of signet ring cell carcinoma were randomly distributed in the superficial and deep regions. The adenocarcinoma was gradually transitioning from dysplasia, while the signet ring cell carcinoma was surrounded by hyperplastic foveolar epithelium. This is the first report of a gastric IHP with multifocal intramucosal adenocarcinomas and a signet ring cell carcinoma, and endoscopic submucosal dissection is used to completely resect it.

A Pedunculated Submucosal Lesion in the Stomach with Inverted Downgrowth

“…A similar lesion was recently called an IHP in other reports (2,7,8). Although several gastric IHPs accompanied by adenocarcinoma have been reported recently, histopathological criteria have not been established for these submucosal lesions, including hamartomatous polyps, hamarto- (2,7,8,10), although the pathogenesis remains unclear.…”

“…Although several gastric IHPs accompanied by adenocarcinoma have been reported recently, histopathological criteria have not been established for these submucosal lesions, including hamartomatous polyps, hamarto- (2,7,8,10), although the pathogenesis remains unclear. Yamashita et al (2) suggested that IHP may be gastritis cystica profunda (GCP) associated with exaggerated hyperplastic and metaplastic changes, and they showed that two out of their four patients with IHP had coexisting GCP.…”

“…Polyptype IHP can be removed by endoscopic resection (4,8), while surgical resection should be considered for the SMTtype lesions or larger lesion of any type, because of the difficulty of removing it in one piece (5,7). Considering the possibility of coexisting adenocarcinoma in gastric IHP, en bloc resection is preferred to avoid residual cancer cells and relapse (11).…”

“…This lesion has previously been described as a hamartomatous polyp, hamartoma mimicking a submucosal tumor (SMT), hamartomatous inverted polyp and heterotopic inverted polyp (2)(3)(4)(5). A similar lesion has recently been called an inverted hyperplastic polyp (IHP) because of its similarity to its colonic counterpart (6), and more than 30 cases of gastric IHP have been reported (7,8). Although these submucosal lesions have been considered to be benign in nature, the pathogenesis of these lesions is not fully understood, and histopathological criteria have not been established.…”

“…Although these submucosal lesions have been considered to be benign in nature, the pathogenesis of these lesions is not fully understood, and histopathological criteria have not been established. Moreover, several gastric IHPs accompanied by adenocarcinoma have recently been reported (2,(7)(8)(9). In this report, we describe a gastric submucosal lesion with inverted downgrowth which was diagnosed and treated by endoscopic mucosal resection (EMR).…”