A Semi-Pedunculated Mucosal Gastric Cancer of 0-I Type with Remarkable Lymph Follicle Formation in the Mucosal Muscle Layer

A protruded tumor on the lesser curve of lower gastric body was detected by a barium meal for medical check-up in a 64-year-old man. Endoscopically, it was a doom-like protruded lesion, 3 cm in diameter, and biopsy revealed a well differentiated adenocarcinoma. Endoscopic ultrasonography showed that it was semi-pedunculated and the depth seemed to be limited in mucosal or shallower submucosal layer. Therefore, the tumor was treated endoscopically and pathological diagnosis revealed a mucosal cancer with lymphatic vessel infiltration. Furthermore, beneath it, remarkable lymph follicle formation was observed in the mucosal muscle layer and component of moderately to poorly differentiated adenocarcinoma invaded those lymph follicles. Because lymphatic vessel infiltration and component of poorly differentiated adenocarcinoma were observed, the patient underwent an additional surgery, but no residual tumor or lymph node metastasis was found. This case was well worth reporting, because of the rare macroscopic shape and remarkable lymph follicle formation in the mucosal muscle layer accompanied with the tumor invasion.