A 55-year-old man with a 10-year history of ulcerative colitis (pancolitis) undergoes surveillance colonoscopy. A flat, velvety red patch is biopsied from the sigmoid colon and histology shows markedly dysplastic glands throughout the full thickness of the mucosa with cytological atypia and loss of nuclear polarity, but no invasion through the muscularis mucosae. What is the significance of this finding?

• A This is reactive atypia from active inflammation and requires only medical management
• B This is dysplasia-associated lesion/mass (DALM) indicating high risk of synchronous or metachronous colorectal carcinoma ✓
• C This represents a hyperplastic polyp with no malignant potential
• D This is a tubular adenoma arising sporadically, managed by polypectomy alone

Explanation

In the setting of longstanding ulcerative colitis, flat dysplasia identified on surveillance biopsy (previously termed DALM — dysplasia-associated lesion or mass) is a high-risk precursor lesion. High-grade flat dysplasia in UC carries a significant risk of synchronous or subsequent invasive colorectal carcinoma and is generally an indication for total proctocolectomy. This is distinct from reactive atypia (which shows preserved nuclear polarity) and from sporadic adenomas, which arise on a background of normal mucosa without chronic colitis.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.