Histopathological examination of the resected specimen revealed spindle cell proliferation, and infiltration of lymphocytes and plasma cells with fibroedematous stroma, in the submucosal layer (Fig. 2A). The spindle cells were immunopositive for CD34 (Fig. 2B) and immunonegative for c-kit, smooth muscle actin, and S-100 protein. Based on these findings, an inflammatory fibroid polyp (IFP) of the stomach was diagnosed. Because the tumor was completely resected, further treatment was not pursued. No recurrence was observed on follow-up endoscopy one year later.

IFPs are rare, benign, mesenchymal tumors occurring throughout the gastrointestinal tract, and they are most commonly found in the gastric antrum [1]. Although the pathogenesis and etiology of IFPs remain unclear, an association with local inflammatory response caused by injury, infection, or metabolic triggers has been suggested [2]. The typical endoscopic findings are semi-pedunculated, subepithelial tumors covered by normal mucosa, often with ulceration, in the gastric antrum. Although IFPs are generally considered benign lesions, it is challenging to diagnose before resection, similar to other mesenchymal tumors located in the submucosa or muscularis propria [3]. Therefore, endoscopic resection and surgical resection are sometimes performed for therapeutic and diagnostic purposes [4].

In the present case, the tumor was located at the gastric fundus, a rare location for IFPs, and its size had increased during the follow-up. Therefore, a malignant lesion, such as a neuroendocrine tumor or gastrointestinal mesenchymal tumor, was suspected. Traction-assisted endoscopic submucosal dissection was performed to provide adequate visualization, facilitating a complete and safe submucosal dissection.