A limitation of endoscopic ultrasound: an unusual case of early gastric cancer overlying a pancreatic rest.

Endoscopic ultrasonography (EUS) has been developed as a valuable tool for examining the depth of carcinoma invasion and evaluating the submucosal tumors of the gastrointestinal tract. In the present case, that of a 60-yr-old woman, the work-up of radiography and conventional endoscopy revealed an ulcerating cancer of the stomach. Subsequent EUS showed a solid high-echoic mass occupying the third (submucosal) and fourth (muscularis propria) layers of gastric wall, suggestive of an advanced cancer invading the muscularis propria. However, histologic examination of the surgical specimen showed that this tumor was early submucosal carcinoma confined to the surface of a pancreatic rest. Retrospective evaluation of EUS pictures proved that the mass had tubular or circular echoless structures associated with thickening of the fourth layer, suggesting the pancreatic rest. Our experience in reviewing EUS findings of this tumor seems noteworthy, inasmuch as EUS indicates that EUS may provide certain characteristic features of gastric pancreatic rest that should be differentiated from invading carcinoma.