Pseudomalignant ulcerative change of the gastrointestinal tract

The occurrence of pseudomalignant ulcerative change in seven specimens from the colon and rectum of six patients is described. In all cases, there was surface ulceration of a polypoid lesion which contained granulation tissue and acute and chronic inflammation. There was an underlying inflammatory pseudopolyp in four lesions, a juvenile polyp in one lesion, an adenomatous polyp in one lesion, and a benign retention polyp in one lesion. Within the stroma of all cases were numerous atypical cells that mimicked a malignant neoplasm. The atypical cells expressed vimentin in immunohistochemical studies; no expression of keratins, leukocyte common antigen, factor VIII, Ulex europaeus, carcinoembryonic antigen, actin, or desmin was found. Recognition of this lesion is important, as confusion with carcinoma, lymphoma, sarcoma, or a viral infection may easily occur.