Probable IgG4-related sclerosing disease presenting as a gastric submucosal tumor with an intense tracer uptake on PET/CT: a case report.

A 44-year-old man consulted an internist because of abnormalities in an upper gastrointestinal series. It showed an elevated lesion with central depression in the greater curvature of the middle part of the stomach. Upper gastrointestinal endoscopy showed an elevated lesion with central depression, bridging hold, and no abnormalities of the gastric mucosa in the greater curvature of the middle part of the stomach. Endoscopic ultrasonography showed a submucosal tumor derived from the muscle layer of the stomach. Computed tomography showed a 22-mm tumor in the upper part of the stomach. Integrated position emission tomography/computed tomography (PET/CT) showed an intense tracer uptake by the tumor. Based on these findings, a gastrointestinal stromal tumor was suspected and laparoscopic endoscopic cooperative surgery was performed. A histopathological examination showed lymphoplasmacytic infiltration and fibrosis, and an immunohistochemical analysis showed the infiltration of IgG4-positive lymphoplasmacytic cells. The probable diagnosis was IgG4-related sclerosing disease of the stomach. We herein describe a rare case of probable IgG4-related sclerosing disease which presented as a gastric submucosal tumor. PET/CT is a useful imaging technique for the diagnosis and follow-up of this disease.