Localised giant pseudopolyposis secondary to ulcerative or granulomatous colitis

Pseudopolyps which represent polypoid oedematous tags, regenerating mucosal islands between ulcerations or heaped-up granulation tissue covered by epithelium, are a common sequela of ulcerative colitis and may also occur secondary to granulomatous colitis. Occasionally, a large discrete mass of pseudopolyps occurs simulating a villous-like or polypoid neoplasm and the term 'localised giant pseudopolyposis' has been applied to this phenomenon. In this paper the radiological appearances of localised giant pseudopolyposis secondary to ulcerative or granulomatous colitis are described and illustrated. The differential diagnosis is discussed and four new cases are added to eight previously reported in the literature.