Gastric inverted hyperplastic polyp with inflammatory myofibroblastic tumor-like stroma, mimicking GI stromal tumor

Abstract

A 46-year-old asymptomatic man with no pertinent medical history underwent routine screening EGD, which showed a 2-cm submucosal tumor with central ulceration in the anterior wall of the gastric high body (A). EUS revealed a heterogenous (hypoechoic-hyperechoic) submucosal mass (B). CT of the stomach revealed a solid enhancing mass (C). Because malignant GI stromal tumor could not be completely ruled out, wedge resection of the stomach was performed. On microscopy, the 3.3-cm mass comprised hyperplastic mucosal components growing downward into the submucosa. Focal stroma showed spindle cell proliferations with vimentin and SMA (+), c-kit, CD34, DOG-1, S100, and ALK (−), and Ki-67 index, 2%. The final diagnosis was gastric inverted hyperplastic polyp with inflammatory myofibroblastic tumor (IMT)-like stroma (D). When fluorescence in-situ hybridization for ETV6, RET, and ROS1 were used, gene rearrangements were not observed in the IMT-like stroma. No recurrence was observed during 10 months of follow-up.