ABSTRACT
The word ‘‘polyp’’ is a nonspecific clinical term that describes any projection from the surface of the intestinal mucosa regardless of its histologic nature. Polyps can be conveniently classified according to their histologic appearance:
1. Neoplastic tubular adenoma, villous adenoma, and tubulovillous, adenoma and serrated adenoma
2. Hamartomatous-juvenile polyps, Peutz-Jeghers syndrome (PJS), Cronkhite-Canada syndrome, Cowden’s disease
3. Inflammatory-inflammatory polyp or pseudopolyp, benign lymphoid polyp
4. Hyperplastic
& NEOPLASTIC POLYPS
Adenomas A neoplastic polyp is an epithelial growth composed of abnormal glands of the large bowel. A neoplastic polyp has been termed an adenoma and is classified according to the amount of villous component. Those with 0% to 25% villous tissue are classified as tubular adenomais, 25% to 75% as tubulovillous adenomas, and 75% to 100% as villous adenomas (1). Tubular adenomas (Fig. 1) account for 75% of all neoplastic polyps; villous adenomas (Fig. 2), 10%; and tubulovillous adenomas (Fig. 3), 15%. The villous growth pattern is most prominent in sessile large adenomas, particularly those located distally in the rectum. There remains considerable uncertainty as to the nature of villous growth, whether it is merely a manifestation of continued growth of tubular adenomas, or whether it is a distinct phenotype that may reflect an acquired genetic change. In favor of the former is the rarity of small villous adenomas and large purely tubular adenomas (1).
