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colorectal inflammatory pseudopolyp

Tuesday 20 March 2012

Inflammatory pseudopolyps are not true mucosal proliferations.

Rather, they are areas of inflamed regenerating mucosa that project into the colonic lumen.

As a result they may grossly resemble pedunculated or sessile adenomas.

Exceptionally, they may be very large, owing principally to an expansion of the stromal fibrous tissue.

Such polyps often have an irregular surface.

They have no malignant potential but their presence does not rule out other lesions in the colon.

Inflammatory polyps occur most frequently in patients with colitis and sites of mucosal injury, including ulcers and anastomoses.

They often appear as multiple, small sessile, sometimes ulcerated polyps.

The ulcerated mucosa is partially replaced by exuberant, edematous granulation tissue admixed with an intense inflammatory cell infiltrate.

The lamina propria contains dilated crypts with both epithelial degeneration and regeneration and variable surface erosion.

The crypts typically appear irregularly branched, dilated, and regenerative.

Cryptitis and crypt abscesses may be prominent.

Occasionally, hyperchromatic mucin-depleted regenerative epithelium simulates adenomatous epithelium.

However, in contrast to adenomatous tissue, the epithelium usually shows evidence of maturation toward the surface.

In patients with ulcerative colitis the changes mimic dysplasia, but the inflammatory background should alert one to being careful to not overdiagnose the lesions as dysplasia.

The lesions may also contain marked atypia.

The lesions may also mimic juvenile polyps and the polyps of some ofthe rare polyposis syndromes discussed.

A knowledge of the clinical features (the presence of a polyposis syndrome or a colitis) helps distinguish between these possibilities.