Polyps of the Colon and Rectum Made by : Dani Mamo

Definition An intestinal polyp is any mass of tissue that arises from the bowel wall and protrudes into the lumen. Most are asymptomatic except for minor bleeding, which is usually occult. The main concern is malignant transformation; most colon cancers arise in a previously benign adenomatous polyp.

Cont.. Polyps may be sessile or pedunculated and vary considerably in size. Incidence of polyps ranges from 7 to 50%; the higher figure includes very small polyps (usually hyperplastic polyps or adenomas) found at autopsy. Polyps, often multiple, occur most commonly in the rectum and sigmoid and decrease in frequency toward the cecum. Multiple polyps may represent familial adenomatous polyposis. About 25% of patients with cancer of the large bowel also have satellite adenomatous polyps.

Why did I develop a colonic polyp? The exact cause of colonic polyps is not known in most cases, but it is thought to be due a combination of lifestyle and genetic factors. Lifestyle factors include a high fat diet, low fibre diet, diet high in red meat, obesity and smoking. Genetics are also important, because colonic polyps and bowel cancers can run in families. There are some genetic diseases (e.g. familial adenomatous polyposis coli) which can cause many colonic polyps to form in early adulthood, and subsequent higher risk of bowel cancer.

In general, you are at higher risk of having colonic polyps if: you are older than 50 you have had polyps before there is a family history of polyps there is a family history of bowel cancer

What are the chances of a colonic polyp developing into cancer? The chance of a cancer forming is determined by the type, size and number of polyps found. In general, large adenomatous polyps are associated with the highest risk.

Classification of polyps The appearance of colonic polyps during a colonoscopy may vary considerably. Polyps may be “sessile” (flat) or “pedunculated” (with a stalk). The polyp size may also vary. Colonic polyps can be classified based on their microscopic appearance into adenomatous and non-adenomatous polyps. Adenomatous polyps are of greater concern as they have a greater risk of developing into bowel cancer. It is not always possible to differentiate between these types of polyp on the appearance during colonoscopy alone, and so removal for analysis is recommended.

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microscopic appearance of adenomatous polyps

Symptoms and Signs Most polyps are asymptomatic. Rectal bleeding, usually occult and rarely massive, is the most frequent complaint. Change in color of the stools Change in bowel habits Nausea , vomiting Iron deficiency anemia ( from bleeding ) Cramps abdominal pain, or obstruction may occur with a large lesion. Large villous adenomas may rarely cause watery diarrhea that may result in hypokalemia.

Diagnosis Colonoscopy Diagnosis of colonic polyps is usually made by colonoscopy. Barium enema, particularly double-contrast examination, is effective, but colonoscopy is preferred because polyps also may be removed during that procedure.

Diagnosis cont … Because rectal polyps are often multiple and may coexist with cancer, complete colonoscopy to the cecum is mandatory even if a distal lesion is found by flexible sigmoidoscopy. Rectal polyps may be palpable by digital examination Occasionally, a polyp on a long pedicle may prolapse through the anus.

colorectal polyp subtype and what features were demonstrable using optical projection tomography (OPT)

Treatment Complete removal during colonoscopy Sometimes follow with surgical resection Follow-up surveillance colonoscopy

Polyps should be removed completely with a snare or biopsy forceps during total colonoscopy. If colonoscopic removal is unsuccessful, laparotomy should be done. Tattooing the distal margin of the polyp with India ink helps the surgeon locate the polyp during laparotomy.

Subsequent treatment depends on the histology of the polyp. If dysplastic epithelium does not invade the muscularis mucosa, the line of resection in the polyp’s stalk is clear, and the lesion is well differentiated, endoscopic excision and close endoscopic follow-up should suffice. Patients with deeper invasion, an unclear resection line, or a poorly differentiated lesion should have segmental resection of the colon.

Because invasion through the muscularis mucosa provides access to lymphatics and increases the potential for lymph node metastasis, such patients should have further evaluation (as in colon cancer).

What is Endoscopic Mucosal Resection (EMR)? EMR is a modification of the standard polypectomy technique. EMR allows the safe endoscopic removal of very large and flat polyps (greater than 20 mm).  Until recently, patients with these types of colonic polyps had to undergo abdominal surgery and a hospital stay for their removal. The technique involves injecting a saline solution beneath the polyp to lift the mucosal layer away from the underlying deeper muscle layer.

Do I need any follow up after colonic polypectomy? People who have adenomatous polyps have a higher rate of forming new polyps over time. Consequently a repeat colonoscopy is recommended. A number of factors determine the time interval for a repeat colonoscopy including: microscopic characteristics of the polyp (histology), number, size, appearance at colonoscopy, adequacy of bowel preparation.

Do my family members need testing if I have colonic polyps? In general, all people should undergo bowel cancer screening at age 50. However, earlier screening may be recommended in first degree relatives of people who have been diagnosed with either adenomatous polyps or bowel cancer before the age of 55. Earlier screening may also be recommended if polyps/bowel cancer has been detected in multiple family members.

Prevention Aspirin and COX-2 inhibitors may help prevent formation of new polyps in patients with polyps or colon cancer . The potential benefits of long-term therapy with these agents must be weighed against the potential adverse effects (eg, bleeding, renal dysfunction).