A case of gastric lipoma resected by endoscopic submucosa dissection with difficulty in preoperative diagnosis.

A 66-year-old man was referred to our hospital with an increasing subepithelial lesion in the gastric antrum. Using esophagogastroduodenoscopy, a tumor with a steep, 20-mm-high rise protruding in the lumen was observed. The mucosal surface of the tumor was reddish, with ulcers forming at the base. Moreover, the tumor was mobile and soft. A biopsy specimen was taken from the ulcer, but tumor tissue was not collected from the submucosa. Endoscopic ultrasonography (EUS) showed a high echoic mass in the submucosa. However, because the mucosal surface of the ulceration was red, the mesenchymal tumor with internal bleeding was inferred to be lipoma. Additionally, because the tumor was small, flexible, and soft, collecting tumor tissue under EUS-guided fine-needle aspiration was inferred as difficult. We were unable to make a final diagnosis because the lesion showed a small tumor with atypical macroscopic morphology. Therefore, endoscopic submucosa dissection (ESD) was chosen for the diagnostic treatment. Sodium hyaluronate sufficient for separation from the muscular layer was injected into the submucosa. Then submucosal dissection was performed just above the muscle layer. Results demonstrate the possibility of removing the tumor reliably without perforation. Pathological evaluation of the ESD specimen indicated a diagnosis of gastric lipoma.