Paper II
Question
Polyps of intestine
Answer
A polyp is any mass that projects above the level of the surrounding mucosal surface, and can be sessile (broad-based) or pedunculated (attached by a stalk).
Non-neoplastic polyps
- Hyperplastic polyps: Most common type, small, benign, no malignant potential; result from delayed epithelial cell shedding
- Hamartomatous polyps: Juvenile polyps (sporadic, or as part of juvenile polyposis syndrome), Peutz-Jeghers polyps (associated with Peutz-Jeghers syndrome — mucocutaneous pigmentation and increased cancer risk at other sites)
- Inflammatory polyps: Associated with chronic inflammatory conditions (e.g., inflammatory bowel disease “pseudopolyps”)
Neoplastic polyps (adenomas) — the clinically most important category
- Tubular adenoma: Most common type, predominantly tubular glands, generally lower malignant potential
- Villous adenoma: Predominantly finger-like villous projections, larger size, higher malignant potential
- Tubulovillous adenoma: Mixed pattern, intermediate risk
Malignant potential of adenomas
- Risk of malignant transformation correlates with: size (>2 cm higher risk), villous architecture (higher risk than tubular), and degree of dysplasia (high-grade dysplasia carries greater risk)
- Adenomas represent the precursor lesion in the adenoma-carcinoma sequence, the major pathway for sporadic colorectal cancer development
Polyposis syndromes
- Familial adenomatous polyposis (FAP) — APC gene mutation, hundreds to thousands of adenomatous polyps, near-100% risk of colorectal cancer if untreated
- Peutz-Jeghers syndrome, juvenile polyposis syndrome — hamartomatous polyps with increased cancer risk