Colonic polyps are an abnormal outgrowth on the bowel wall that projects into the lumen of the bowel. Colonic polyps most commonly arise as a mass from the lining of the large intestine.
Colonic polyps are divided into two groups which are known as a neoplastic colonic polyp and non - neoplastic colonic polyp. Most are benign and occur as a result of abnormal proliferation of the mucosal epithelium. Careful treatment and investigation are required due to its malignant potential to transform into colorectal carcinoma.
Colonic polyps such as metaplastic /hyperplastic polyps, hamartomatous polyps and inflammatory polyps are non neoplastic polyps. They are benign. Metaplastic/hyperplastic polyp account for 90% of all colonic epithelial colon. Neoplastic colonic polyp may include adenoma such as tubular adenoma, tubulovillous adenoma and villous adenoma. Villous adenoma is more likely to become malignant and it is presented as a large polyp.
There are a few syndromes that are associated with multiple colonic polyps . These disorders are Cronkhite -Canada syndrome, Turcot syndrome, Gardner syndrome, familial polyposis coli, inflammatory bowel disease and Peutz -Jeghers syndrome.
Cronkhite -Canada syndrome is presented with various manifestations such as watery diarrhea, pigmentation, multiple colonic, stomach and small intestinal adenoma, nail atrophy and alopecia. Cronkhite - Canada syndrome is associated with a pre- malignant state. It is an autosomal dominant disorder.
Turcot syndrome is an autosomal dominant disorder . A patient who suffers from Turcot syndrome may also suffer from glioblastomas and medulloblastomas besides multiple colonic adenoma (pre-malignant state).
Osteomas, sebaceous cysts , soft tissue tumor and congenital hypertrophy of retinal pigmentary epithelium is associated with Gardner syndrome. Gardner syndrome is inherited in an autosomal dominant pattern and it is also form part of the pre malignant state.
Familial polyposis coli is an autosomal dominant condition. It is caused by mutation of the APC gene and presented with multiple colonic adenoma /pre malignant state which later transform into colorectal carcinoma. Pseudo polyps are commonly associated with inflammatory bowel disease due to the sloughing of the mucosal lining the bowel. However, ulcerative colitis which form part of the inflammatory bowel disease has a high risk of malignancy.
Peutz -Jeghers syndrome is an autosomal dominant disorder. It is presented with mucocutaneous pigmentation of the gum and lips. Besides that Peutz- Jeghers syndrome also associated with diffuse gastrointestinal polyps which are benign.
Colonic polyps are common in industrialized countries. Men are more commonly affected with adenoma than women. In terms of incidence , 50% of the patient age > 60 years old are prone to develop colonic polyps and 20% of the older adult and middle age men are also prone to develop colonic polyps. The prevalence of colonic polyps are ranging from 25% in < 40 years up to 55% for anyone of the age of 80 years old.
The risk factors for developing colonic polyps may include family history, men, obesity, advancing age, inflammatory bowel disease, family history of cancer or polyps, excessive alcohol intake , cigarette smoking and sedentary lifestyle.
The patient may appear asymptomatic in most of the cases, However some patients may complain about a change in bowel habit. They complain of constipation of diarrhea. The incidence of per rectum bleeding , melena, hematochezia and mucoid diarrhea are also common. The patient generally may also feel tired, fatigue and suffer from abdominal pain. The patient may be anemic due to the loss of blood per rectum .
While performing a physical examination, colonic polyps may be palpable on per rectum examination if it is located low in the rectum. However in most cases, there is no significant finding on per rectum examination. A patient who suffers from a multiple polyposis syndrome may present with other other associated conditions.
In terms of gross pathology, the polyps may be pedunculated or sessile in shape and the sizes range in term of diameter from a few mm to cm . Microscopically, the polyps may include non - neoplastic polyps/non adenomatous polyps or neoplastic polyps /adenomatous polyps. Non adenomatous polyps occur as a result of the abnormal maturation of the mucosal layer, abnormal mucosal architecture or inflammation of the mucosal. Adenomatous polyps are originated from dysplasia and abnormal proliferation of the mucosal epithelium layer.
The non - neoplastic polyps are hyperplastic polyps and hamartomatous polyps. Hyperplastic polyps are formed from an accumulation of mature epithelial cell due to decrease in the cell turnover. It represents 90% of the polyps in the large intestine. Hyperplastic polyps appear as a small <5mm diameter polyps. It is hemispheric, moist, smooth and protrude of the mucosa. Hyperplastic polyp locates on the top of the mucosal fold. It is composed of the crypts and glands which is lined by non neoplastic epithelial cell which differentiate into absorptive and mature goblet cells.
The neoplastic polyps are also known as the adenomatous polyps. It includes tubular, tubulovillous and villous adenoma. Tubular adenoma , microscopically present with hyperchromatic, elongated nuclei and the proliferation of gland in tabular fashion. In terms of gross pathology it is pink, firm and smooth in surface. It is also microlobulated, pedunculated and contain tissue.
Villous adenoma microscopically is presented with malignant degeneration and gland which proliferate in a finger like projection. Macroscopically it consists of multiple front projection and velvet in appearance.
The investigation need to confirm the presence of colonic polyps may include blood test, fecal occult blood test and endoscopy such as colonoscopy, virtual colonoscopy, sigmoidoscopy and air contrast barium enema. The blood test may include full blood count. In some cases, patient may be anemic due to per rectum bleeding. Stool examination may include a focal occult blood test to detect the presence of any occult /frank blood in the stool. The gold standard of investigation is colonoscopy. Upper gastrointestinal endoscopy is recommended in patients who suffer from the multiple polyposis syndrome. It is possible that polyps may also present in the upper gastrointestinal tract in patients who suffer from the multiple polyposis syndrome. The malignant potential of the polyp is assessed by histological assessment of the polyps that are removed during endoscopy.
The management of colonic polyps may include advice on general prevention. The patient should reduce the amount of alcohol intake, stop smoking, consider calcium supplement, high fiber and low fat diet and increase intake of vitamin B6, vitamin D and folic acid. Acetylsalicylic acid will reduce the formation of polyps in familial polyposis coli patient.
The treatment may include endoscopy procedure or surgical resection. The endoscopy procedure also known as endoscopic polypectomy involved in the removal of polyps which are small and isolated. There are major risks of bleeding perforation. Surgical resection is considered for patients who present with large polyps. This procedure is mostly performed in patients who suffer from the multiple polyposis syndrome such as familial adenomatous polyposis coli. It involves early subtotal colectomy /colonic resection to reduce the risk if further malignancy. The patient will require a follow up every 2- 4 years after the removal of colonic polyps. The follow up will consists of colonoscopic examination of the patient's intestine. It is recommended for first degree relatives to undergo genetic screening test if there are any multiple colonic polyps run in the family.
The complication of colonic polyps may include malignant transformation that occurs in patients who suffer from the multiple polyposis syndrome and villous adenoma. There is also a risk of perforation while performing colonoscopy as well as bowel obstruction.
The prognosis is good it if is detected and treated early with polypectomy . Colonoscopy screening for people age > 50 years is recommended.
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