Non-neoplasticColonic Polyps

Lecture 14By

Dr Mohammad Manzoor Mashwani BKMC Mardan

Polyps are most common in the colon but may occur in theesophagus, stomach, or small intestine.

Definition of PolypA polyp is defined as any growth or mass protruding from the mucous membrane

into the lumen.• Classification:

• Stalked or pedunculated polyp• Sessile polyp

Non-neoplastic & Neoplastic Polyps

As sessile polyps enlarge, proliferation of cells adjacent to the polyp and the effects of traction on the luminal protrusion, may combine to create a stalk.

Non-neoplastic Colonic Polyps

Non-neoplastic Polyps 90%Hyperplastic polyps- most commonHamartomatous polypsJuvenile polypsPeutz-Jeghers polypsInflammatory polypsLymphoid polyps

Neoplastic Colonic Polyps

• Neoplastic Epithelial Lesions• Benign polyps• Adenomas• Malignant lesions

Adenocarcinoma Squamous cell carcinoma of the anus

Non-neoplastic polyps

of intestine

Hyperplastic polyps

Hamartomatous polyps

Juvenile polypsPeutz-Jeghers polyps

Inflammatory polyps

Lymphoid polyps

Non-neoplastic Polyps

• The overwhelming majority of intestinal polyps occur sporadically, particularly in the colon, and increase in infrequency with age.

• Non-neoplastic polyps represent 90% of all epithelial polyps in the large intestine and are found in more than half of all persons age 60 years or older.

I. Hyperplastic Polyps (Metaplastic)

• The most common amongst all epithelial polyps.• Most common in the left colon (rectosigmoid).• Called hyperplastic because there is epithelial

hyperplasia at the base of crypts, and metaplastic as there are areas of cystic metaplasia.

• More common in elderly (6th-7th decade).

Pathogenesis The pathogenesis of hyperplastic polyps is incompletely understood, but they are

thought to result from

decreased epithelial cell turnover and delayed shedding of surface epithelial cells, leading to a “pileup” of goblet cells and absorptive

cells.

MorphologyGROSS- Most commonly found in the left colon (rectosigmoid) and

• Small ( <5 mm in diameter), multiple, smooth-surfaced, sessile.

Microscopy - composed of mature goblet and absorptive cells, long & cystically dilated glands & crypts.

• The delayed shedding of these cells leads to crowding that creates

the serrated surface (Saw-toothed) architecture that is the

morphologic hallmark of these lesions.

Hyperplastic polyp. A, Polyp surface with irregular tufting of epithelial cells. B, Tufting (bunch) results from epithelial overcrowding. C, Epithelial crowding produces a serrated

architecture when glands are cut in cross-section.

Hamartomatous polypsOccur sporadically and in the context of various

genetically determined or acquired syndromes . Recall that hamartomas are tumor-like growths

composed of mature tissues that are normally present at the site in which they develop.

Although Hamartomatous polyposis syndromes are rare, they are

important to recognize because of associated intestinal and extra-intestinal manifestations and the need to screen family members.

Juvenile Polyps (Retention polyps)

• Juvenile polyps are the most common type of hamartomatous polyp.

• Juvenile polyps are focal malformations of the mucosal epithelium and lamina propria.

• These may be sporadic or syndromic. • The vast majority of juvenile polyps occur in

children less than 5 years of age. • When present in adults, polyps with identical morphology are

sometimes confusingly referred to as inflammatory polyps.

• The majority of juvenile polyps are located in the

rectum and most present with rectal bleeding. In some cases prolapse occurs and the polyp protrudes through the anal sphincter.

• Sporadic juvenile polyps are usually solitary lesions and may be referred to as retention polyps.

• In contrast, individuals with the autosomal dominant syndrome of juvenile polyposis have from 3 to as many as 100 hamartomatous polyps

and may require colectomy to limit the chronic and sometimes severe hemorrhage associated with polyp ulceration.

• A minority of patients also have polyps in the stomach and small bowel. Pulmonary arteriovenous malformations are a recognized extra-intestinal manifestation of the syndrome.

Dysplasia occurs in a small proportion of (mostly syndrome associated)

juvenile polyps, and the juvenile polyposis syndromeis associated with increased risk for the development of colonic adenocarcinoma.

MorphologyIndividual sporadic and syndromic juvenile polyps often are indistinguishable.

Gross- Spherical, pedunculated, smooth surfaced, reddish lesions that are <3 cm in diameter and display characteristic cystic spaces on cut sections.

Microscopic examination – cystically dilated glands filled with mucin and inflammatory debris

Juvenile polyposis. A, Juvenile polyp. Note the surface erosion and cystically dilated crypts. B, Inspissated mucous, neutrophils, and inflammatory debris can

accumulate within dilated crypts.

Peutz-Jeghers Syndrome A rare autosomal dominant disorder defined by the presence of multiple gastrointestinal hamartomatous polyps and mucocutaneous hyperpigmentation that carries an increased risk of several malignancies, including cancers of the colon, pancreas, breast, lung, ovaries, uterus, and testes, as well as other unusual neoplasms.

• Intestinal polyps are most common in the small intestine, although they may also occur in the stomach and colon and, rarely, in the bladder and lungs.

Morphology

• Gross- More commonly situated in the small intestine. Often large (variable), multiple & pedunculated with lobulated contour.

• Microscopy- characteristic arborizing network of connective tissue, smooth muscle, lamina propria, and glands lined by normal-appearing intestinal epithelium.

• Tree-like branching of muscularis mucosae. The gland may show hyperplasia & cystic change.

Peutz-Jeghers polyp. A, Polyp surface (top) overlies stroma composed of smooth muscle bundles cutting through the lamina propria. B, Complex glandular architecture and the presence of smooth muscle are features that distinguish Peutz-Jeghers polyps from juveni le

polyps.

Inflammatory Polyps (Pseudopolyps)

The polyp that forms as part of the solitary rectal ulcer syndrome is an example of the purely inflammatory lesion.

Patients present with the clinical triad of rectal bleeding, mucus discharge, and an inflammatory lesion of the anterior rectal wall.

• The underlying cause is impaired relaxation of the anorectal sphincter, creating a sharp angle at the anterior rectal shelf. This leads to recurrent abrasion and ulceration of the overlying rectal mucosa. Chronic cycles of injury and healing produce a polypoid mass made up of inflamed and reactive mucosal tissue.

• Inflammatory polyps or pseudopolyps appear due to reepithelialisation of the undermined ulcer & overhanging margins in inflammatory bowel disease, most frequently in ulcerative colitis & sometimes in Crohn’s disease.

A projecting mass of hypertrophied mucous membrane (as in the stomach or colon) resulting from local inflammation

Solitary rectal ulcer syndrome. A, The dilated glands, proliferative epithelium, superficial erosions, and inflammatory infiltrate are typical of an inflamatory polyp. However,

the smooth muscle hyperplasia within the lamina propria suggests that mucosal prolapse has also occurred. B, Epithelial hyperplasia. C, Granulation tissue-like capillary

proliferation within the lamina propria caused by repeated erosion and re-epithelialization.