Hyperplastic Polyp of the Colon

Definition

A hyperplastic polyp is a proliferation and overgrowth of normal mucosal cells, and is characterized as a small sessile lesion, commonly located in the distal sigmoid and rectum. It is the most common polyp in the colon and represents about 70-90% of polyps identified. They are usually the same color or perhaps lighter than the surrounding mucosa. The hyperplastic polyps are usually small (<6mm) and have no macroscopic features that would enable the endoscopist to distinguish them from adenomatous polyps. Their cause likely relates to diet and environmental factors, since they are commonly seen in Western cultures, and as small lesions, they have no definite known malignant potential. They are usually diagnosed histologically after removal at colonoscopy, and are thus coincidentally treated.

Nomal (left) and Hyperplastic Polyp (right)

The left image shows a normal colonic mucosa. This is a low power photo micrograph of normal colon mucosa illustrating extremely orderly, rigid, “test tube”-like arrangement of the straight tubular glands which comprise the colonic crypts. The right image shows a photomicrograph at low power, showing a hyperplastic polyp of the colon. The characteristic histology is simply hyperplasia of the epithelium of existing crypts with infoldings, creating a “sawtooth” pattern in the epithelium. These polyps are typically 2 or 3 mm in diameter. colon large bowel fx polyp fx sawtooth pattern fx hyperplasia dx hyperplastic polyps histopathology Courtesy Barbara Banner MD 12307b01

Multiple Polyps

This path specimen shows five polyps on the surface of the colonic mucosa. Based on the size and lobular surface, it is very likely that the polyps overalid in light green are adenomatous polyps and are likely to be tubular adenomas. The polyps overlaid in dark green , one being the same color of the mucosa and rthe second lighter than the mucosa could represent hyperplastic or adenomatous polyps. Their size smoothness and color would favor hyperplastic polyps but their location in the transverse colon would favor adenomatous polyps. Histological examination is essential to make the distinction.

00362c02 colon large bowel mass polyp multiple polyps adenomatous polyps hyperplastic polyps grosspathology Courtesy Barbara Banner MD Ashley Davidoff MD

5mm benign polyp

This 5mm polyp is a common finding on colonic evaluation and at this size is a benign abnormality. Left intact it can grow into a monster. Hence it is usually removed by the endoscopist. It could represent a hyperplastic or adenomatous polyp at this stage.

Courtesy Ashley Davidoff MD

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Benign Polyp – virtual colonoscopy
This series of images from a virtual colonoscopy shows an 8 mms polyp seen on the surface rendering images (salmon colored images) referenced to the sigmoid colon (bottom left) and with conventional CTimaging (bottom middle) At this size the polyp is almost certainly benign and can be removed through the colonoscope safely. Note in the gray scale image (middle image 2nd row) the acute angles formed by the polyp with the underlying mucosa. The distal location raises the likelihood that it represents a hyperplastic polyp.
Courtesy Scott Tsai MD
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Small Rectal Polyp

This 5mm rectal polyp likely represents a hyperplastic polyp based on its size location, and the relative frequency of hyperplastic polyps in general.

00363c01 colon large bowel rectum fx nodule dx rectal polyp likely hyperplastic polyp BE barium enema Courtesy Ashley Davidoff MD