Features of cap polyposis by magnifying colonoscopy

Cap polyposis (CP) is a rare disease that was first described by Williams et al.1 in 1985. It is characterized by multiple polyps with a mucoid and fibrinopurulent cap. Although the pathogenesis is unknown, the characteristic histological appearance is similar to that of mucosal prolapse syndrome (MPS). Endoscopically, it is difficult to distinguish the polyps of CP from inflammatory polyps and neoplasms. True neoplasms can be differentiated from non-neoplastic lesions by magnifying colonoscopy, but the changes in the mucosal surface of CP have not been investigated in detail. A case of CP that was treated successfully with conservative therapy, is described, as well as the findings obtained by magnifying colonoscopy.