PMC10080140_01
Endoscopic and endoscopic ultrasound findings and ESE images. (A) The upper gastrointestinal endoscopy shows a submucosal protrusion at the lesser curvature of gastric antrum. The tumor surface is covered by normal gastric mucosa. (B) The EUS shows the hypoechoic lesion originating from the submucosa. (C) The wounds after ESE. (D) The resected tumor tissue.
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An upper gastrointestinal endoscopy revealed a submucosal protrusion with a rough surface on the lesser curvature side of the gastric antrum ( Figure 1A ). An endoscopic ultrasonography (EUS) indicated the clear gastric wall and a hypoechoic lesion located in the gastric submucosa, with a section size of about 7.7 x 4.1mm ( Figure 1B ). Subsequently, ESE was performed to remove the lesion under gastroscopy ( Figures 1C ,  D ): Multiple submucosal injections were conducted at the periphery of the lesion, and the white tumor mass was found to originate from the submucosal layer.
Histological features of the tumor. (A, B) Hematoxylin and eosin staining. (A) Magnification: 10 x; (B) Magnification: 40 x. (C-L) Immunohistochemical staining for vimentin (C), SDHB (D), CD34 (E), CD117 (F), DEMSIN (G), SMA (H), DOG1 (I), ALK (J), S100 (K), and CK (L).
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The pathological examination revealed that the resected tissue was irregular nodular hyperplasia consisting of spindle fibroblasts and myofibroblast-like cells ( Figures 2A, B ). ALK-1, and S-100 protein ( Figures 2C-L ). Approximately 2% of the tumor cells expressed the proliferation marker Ki-67.