ABSTRACT
Polypoid prolapse of mucosal folds can occur at various sites and in various conditions predominantly associated with strain during defecation. There are two well known types of mucosal prolapse syndrome(MPS), the inflammatory cloacogenic polyp(ICP) and the mucosal redundant polyp associated with diverticular disease(N4RPD). ICP is a mucosal prolapse of the anorectal junction and MRPD is a proximal analogue involving the sigmoid colon. We experienced two cases of eroded polypoid hyperplasia(EPH) of the rectosigmoid colon which manifested as a huge gyriform mass simulating the gross features of gastrointestinal lymphomas or other malignant tumors. The EPH consisted of confluent polypoid mucosal folds with rolled-up submucosa to form stalk, The polypoid lesion represented hyperplastic epithelium, erosion of the mucosal surface and congestive vascular ectasia of lamina propria and submucosa. To explain the whole morphologic features, the initial phenomenon should be the mucosal prolapse. Vascular stretching with ischemic erosion of the mucosal surface and compensatory epithelial hyperplasia ensue as the result. The ominous endoscopic and gross features of EPH should be kept in mind to avoid erroneous radical surgery.