[A case of diffuse cystic malformation in which submucosal tumor-like advanced gastric cancer was identified during 10-year follow-up].

: A 66-year-old man with giant gastric folds had been followed up since February 2000. In March 2010, a submucosal tumor of 35mm was identified with endoscopy and a low echoic mass was identified with endoscopic ultrasonography. After histologic diagnosis by endosonography-guided fine needle aspiration biopsy, he underwent a total gastrectomy. Histologic examination of the resected specimen revealed a tumor 20mm in diameter consisting of well-to-moderately differentiated tubular adenocarcinoma in the thickened wall of the gastric greater curvature, which contained small cystic lesions in the lamina propria. Immunohistochemical staining showed thick gastric wall consisting of not only multiple cysts but also smooth muscle, elastic and collagen fibers. The histologic diagnosis was advanced gastric cancer accompanied by diffuse cystic malformation (DCM). Although it is a rare condition, DCM should be considered in the differential diagnosis of giant gastric folds and as a pre-cancerous lesion.