Endoscopic Ultrasonographic and Clinicopathological Features of Gastric Inflammatory Fibroid Polyps

Background: Inflammatory fibroid polyp (IFP) is a rare benign gastrointestinal subepithelial lesion with an uncertain origin and natural history. Although it is frequently seen in the stomach, histologic diagnosis is difficult without surgical or endoscopic resection. The endoscopic ultrasonographic (EUS) characteristics of IFPs were sporadically reported on imaging tips or small case series study (Matsushita M). However the differenzial diagnosis and optimal treatment of gastric IFP is still a challenge to in-experienced gastroenterologists.

Aims & Methods: The aim of this study was to evaluate the EUS and clinicopathologic features of gastric IFPs, and the outcome after endoscopic or surgical resection. From Jan 2000 to June 2010, IFPs of the stomach were diagnosed histologically in 15 patients (5 men, 10 women; age range 41 to 73 years, average age 60 years) at endoscopy center. All lesions were solitary and located in the antrum (10), prepyloric region (3) and lower body (2). They were diagnosed by either endoscopic resection (13) or gastrectomy (2). EUS was performed in 11 of the 15 patients before resection and further follow-up in 8 patients. The EUS features and clinical data were reviewed retrospectively. The EUS instruments were conventional radial EUS, GF-UMQ240 (2) and/or mini-probe UM-2R (9)/EU-M30 (Olympus, Tokyo, Japan).

Results: The major clinical presentations on 15 patients were: incidental polypoid lesions (8), ulcer (4), UGI bleeding (3). Of the EUS studies (11), nine lesions (mean 10.6mm, range 7–15.1) were located in the second and/or third sonographic layer, but the other two lesions (31.7mm, 16.3mm) seem involving the fourth layer (muscular propria, MP) without clear separation. The most frequent EUS features were an indistinct margin (82%), and a hypoechoic (100%), homogeneous (91%) echo pattern. During the EUS following-up of IFPs after endoscopy resection, residual or recurrent hypoechoic tumor could be detected on 7 cases (54%); two involving MP, one had increased size (15.1 to 34.5mm) and was treated by surgical resection.

Conclusions: Gastric inflammatory fibroid polyps may have muscular propria involvement on EUS imaging of larger IFPs or after incomplete endoscopic resection. Regular follow-up of EUS is recommended after endoscopic resection because of potential recurrent IFPs.