A case of early gastric cancer arising from gastritis cystica profunda treated by endoscopic submucosal dissection.

Gastritis cystica profunda (GCP) consists of hyperplasia and cystic dilatation of the gastric glands extending into the submucosa. It occurs in the residual stomach post surgery and in the unoperated stomach. GCP is considered a benign lesion, but there is controversy about its malignant potential. We report a case of early gastric cancer arising from GCP treated by endoscopic submucosal dissection (ESD) in a 55-year-old unoperated man. Upper gastrointestinal endoscopy revealed a 15-mm diameter submucosal tumor (SMT) in the upper corpus of the stomach. The surface had angiotelectasia and slight depression covered with normal mucosa. Neither ulceration nor erosion was seen. Narrow-band imaging endoscopy showed no abnormalities suggesting gastric cancer. Endoscopic ultrasonography visualized the internally low-echoic SMT, harboring tiny cystic lesions, mainly within the second and third layers of the gastric wall. The SMT was removed by ESD to avoid retention and allow for comprehensive diagnosis. It was diagnosed as GCP with partial well-differentiated adenocarcinoma without involvement of the lateral and deep margins, lymphatic invasion, vascular invasion and perineural invasion. The gastric epithelium comprised normal mucosa without dysplasia. ESD seems to be useful for the diagnosis of SMT, including GCP harboring gastric cancer, and avoids unnecessary surgical procedures.