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home - Colon - Colorectal and Anal Cancer - Colonic Polyp Type and Character Written by Dr Sebastian Zeki
Knowledge

Knows the pathology of benign and malignant tumours of the colon
and rectum
Has awareness of the molecular genetics of colorectal
carcinogenesis and the adenoma-carcinoma sequence
Knows the range of predisposing conditions including inherited
syndromes and acquired colonic diseases
Knows the range of clinical presentation and the means of
diagnosis, investigation, management and follow-up
Knows the strategy for prevention including procedures for
screening

Skills
Uses clinical assessment and selects investigations to reach a rapid
conclusion as to whether a patient might have colorectal cancer and
arranges timely investigation.
Refers the patient to the multi-disciplinary team CbD, mini-CEX,

Behaviours
Shows ability to react to possible diagnosis of malignancy in a timely
manner

Communicates with patient and family in a sympathetic and
understanding manner, explains next steps, involves other health
professionals (including the GP) as appropriate

Colonic Polyp Type and Character

Risk Factors:Familial adenomatous polyposis + variants- < 1 % of CRC.Hereditary nonpolyposis colorectal cancer (HNPCC)- 1-5 % of CRC.Personal or family history of sporadic cancers or adenomatous polyps.Pancolitis -10x relative risk.L-sided IBD - 3x relative risk.Diabetes mellitus and insulin resistance- ?Insulin is a colonic cell growth factor.Cholecystectomy- inc. rate of R sided cancers in some reports.Alcohol- increased risk due to decreased folate intake and absorption.Obesity- 1.5x relative risk.Coronary Artery Disease-associated with advanced adenomas.Cigarette Smoking- Increased incidence and mortality from colorectal cancer.Ureterocolic anastomoses- Increased risk of neoplasia in close proximity to the ureteric stoma.Acromegaly-Inc. risk of GI cancer and colonic adenomas (more likely multiple adenomas and proximal to the splenic flexure. Red meat-Assoc with CRC esp L sided.Coffee/Tea- Relationship unresolved.Radiation treatment-Inc risk if hx of prostate radiotherapy.Barretts- Conflicting Data.Infections-Mixed and inconclusive. Implicated bugs include Hpylori, Streptococcus bovis, JC virus, HPV, and possibly HIV.Hodgkins- Association with prior Hodgkin’s treatment. Protective Factors:Diet-High in fruits and vegetables and low in red meat, animal fat and/or cholesterol.Fibre- the role isuncertain.Folic acid- unclear association.Vitamin B6 (pyridoxine) - this demonstrates a protective effect as per The Nurses' Health study.Calcium-adequate levels are protective.Magnesium.Physical activity- exercise is protective.Aspirin and NSAIDs- may be protective by reducing COX-2 driven tumour growth.Combination therapy with DFMO (irreversible inhibitor of ornithine decarboxylase) and sulindac gives a significant reduction in adenoma rate.Hormone replacement therapy- may reduce risk.Statins- Data are conflicting.Antioxidants- No convincing protective effect.Omega 3 fatty acids-May be protective.Garlic-May be protective. Polyp stalkSessile polyps are so called if the base is attached to the colon wall.Pedunculated polyps are so called if a mucosal stalk is interposed between the polyp and the wall.Small polyps (<5 mm, also known as "diminutive polyps") are rarely pedunculated. Polyp heightFlat polyps- have a height < 1/2 diameter of the lesion and are more common in the R colon.Depressed polyps occur in 1%- high risk for HGD / malignancy even if small. Tubular adenomas > 80 % of colonic adenomasCharacterized by a network of branching adenomatous epithelium.Tubular component of at least 75 %.Villous adenomas 10 % of adenomas.Histol: long straight glands that extend from surface to the center of the polyp.Villous component of at least 75 %.Tubulovillous adenomas 5 to 15 % of adenomas.10 % of adenomas.Has 26 to 75 % villous component.Serrated adenoma —Benign. MIxed hyperplastic and adenomatous elements.Have a malignant potential- Likely precursor lesions to sporadic MSI CRC.Varieties of serrated adenomasSessile serrated adenoma in hyperplastic polyposis.Admixed hyperplastic polyp/adenomatous polyps, which can be conceived as a "collision" of a traditional adenoma and a hyperplastic polyp. Polyp dysplasiaAll adenomas are dysplastic.Polyps are classified pathologically as high (which includes carcinoma in situ or low grade). Colonic Polyps Adenomas (70% of all polyps) and hyperplastic polyps are the most frequently found. Adenomas have a variable appear-ance and are usually redder than the surrounding tissue but may be normal in colour or even yellow. There may be pedunculated, sessile, flat or carpet-like and the surface smooth, velvety/villous, lobular or nodular. Other polyps types Things that look like polyps:Mucosal prolapse in the sigmoid colon. Inverted appendix or appendix stump. Submucosal lymphoid- Pneumatosis Cystoides Intestinales- Colitis cystica profunda- Lipoma-are pale, yellowish and often demon-strate the pillow sign. Removal should not be attempted unless the patient is symptomatic. Carcinoid Mets Leiomyoma Haemangioma Fibroma EndometriosisEpithelial Non malignant Mucosal Hyperplastic-Pale and smooth with vivible surface vessels. Flat or sessile but may be pedunculated. They may disappear on luminal distension. Inflammatory Hamartoma Epithelial Neoplastic Tubular (85%) Tubulovillous (15%) Villous (5%) CRC incidence of 0.5 %/yr if disease duration 10-20 years, then 1%/yr . Worse if also have PSC Related to reduced expression of PPAR gene Features suggesting malignancy:Ulceration.Surface irregularity with depression.Convergence of folds or expansion of the normal tissue adjacent to the lesion.Friability.A failure of the lesion to lift away from the colonic wall (the non-lifting sign). Punctuate erythema and petechiae and the gradual change in colour from the tip to the base suggests this diagnosis. Glandular Architecture Written by Dr Sebastian Zeki

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