Inflammatory polyp of the colon

by Jason Wasserman MD PhD FRCPC
April 18, 2022


What is an inflammatory polyp in the colon?

An inflammatory polyp is a non-cancerous growth that develops on the inside surface of the colon. This type of polyp can develop anywhere along the length of the colon (from the cecum to the rectum) but they are most commonly found in the sigmoid colon or rectum.

What causes an inflammatory polyp in the colon?

Inflammatory polyps in the colon can be caused by any condition that leads to prolonged inflammation or tissue injury. For example, people with inflammatory bowel disease (IBD) such as ulcerative colitis (UC) are more likely to develop inflammatory polyps, especially in the rectum. However, inflammatory polyps can also be seen in other conditions such as constipation and infection.

How do pathologists make the diagnosis of an inflammatory polyp?

The diagnosis of inflammatory polyp is usually made after a small amount of tissue is removed from the colon during an examination called a colonoscopy. Because inflammatory polyps stick out or protrude from the inner surface of the colon, they are often easy for your doctor to see and remove. The procedure used to remove them may be called a biopsy or polypectomy. The tissue is then sent to a pathologist for examination under the microscope.

inflammatory polyp colon

What does an inflammatory polyp look like under the microscope?

When examined under the microscope, the normal glands are surrounded by a large number of inflammatory cells including neutrophils and plasma cells. Pathologists often use the term reactive to describe the look of the glands surrounded by inflammatory cells. In large polyps, the normal colonic mucosa may be replaced by a type of inflammation called granulation tissue. Finally, the cells that are normally found on the surface of the tissue may be damaged or lost. This is called erosion. A pre-cancerous change called dysplasia is rarely seen in an inflammatory polyp and it is more common in people who have a history of inflammatory bowel disease (IBD).

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