Adenocarcinoma Within Carpet-Like Pseudopolyposis.

Pseudopolyps are benign lesions without malignant potential and typically do not require biopsy or excision. We describe a 68-year-old man with ulcerative colitis found to have multiple large bridging pseudopolyps. Repeated colonoscopies and extensive biopsies revealed a large ulcerated lesion previously hidden within the pseudopolyps. The pathology of the lesion was consistent with a low-grade adenocarcinoma with invasion into the muscularis propria. This demonstrates that large pseudopolyps, although benign, can obscure other lesions with malignant potential. Therefore, in addition to careful inspection, healthcare providers must perform periodic surveillance colonoscopies and offer surgical resection to patients with giant pseudopolyposis.