Diagnostic value of endoscopic ultrasonography in an unusual case of gastric cyst.

Using endoscopic ultrasonography, we diagnosed a gastric antral submucosal cyst with a papillous protrusion in a 71-yr-old woman, apparently the first such case to be detected by this method. Endoscopic ultrasonography demonstrated a well-marginated hypoechoic area with papillary tumor in the submucosal layer that did not extend to the muscularis propria. The lesion was diagnosed as a gastric submucosal cyst. CT and transabdominal ultrasound each failed to detect the intracystic papillary tumor. Follow-up endoscopic ultrasonography performed 6 months later revealed an increase in the diameter of the cyst and the papillary tumor. The patient then underwent a partial gastrectomy for a suspected malignancy. The resected specimen showed a cystic lesion with papillary tumor. Although no malignancy was present, examination of cross-sections of the resected specimen gave results consistent with the endoscopic ultrasonographic findings. Endoscopic ultrasonography is thus useful in assessing the nature of a submucosal gastric cyst in detail and in monitoring patients with this lesion.