Colorectal polypdefinition,types,colonscopic survillence National cancer institute –misrata Surgery department Dr . Mohamed alhashmi sidoun
Colorectal polyp is projecting mass into the lumen of bowel above the surface of epithelium. Polyp is word descriptive for the shape of lesion (not related to the pathological process) Polyposis :multiple polyps Polypoid Colorectal polyps are considerd slow growing tumour The term “malignant polyp” refers to a macroscopically benign appearing adenoma in which the invasive carcinoma is detected after histologic examination of the resected specimen.
Classification of polyps According to the shape According to the histology
According to the shape1. Pedunculated ( with stalk)2. Sessile (no stalk ,no neck )
According to the histopathology Polyps such as hyperplasic,juvenile andinflammatory polyps have no malignantpotential,although polyps do have malignant potentiaType Benign MalignantEpithelial Neoplasma Adenocarcinoma Inflammatory Hamartoma Metaplasticmesenchymal Lipoma Sarcoma Fibroma lymphoma Leiomyoma haemangioma
Neoplasma (1/3 of crc have benignpolyp) Tubular adenoma : 60-80 % usually pedunculated polyp Villous (finger like projection): 5-10 % usually sessile more precancerous cellular changes (sever atypia) Tubulovillous adenoma : 10 – 25 %
The prognostic factors :(polyps transformed to carcinoma)The presence of poor prognostic features shouldlead the physician to favor colectomy1. Polyp size more than 1 cm are found to harbor cancers more than the cells size less than 4 mm usually hyperplastic (no malignant changes but should be excised sessile polyp more than 2 cm usually villous with high malignant changes and high recurrence rate2.Shape of the polyp : the invasion of adenocrcinoma in pedunculated polyp need travel during head,neck,stalk before reaching the submucosa (polypectomy not appropriate) contrast with sessile where just travel the basement membrane
3.Histopatholo of the polyp : the villous subdivision are associated with the highest malignant potential because they have the largest surface area ,no stalk and no neck. 2 cm sized tubular adenoma _35%risk of malignancy 2 cm sized villous adenoma _50 % risk
4.Multiple polyps more prognostic than single (familial adenomatous polyposis) 100% risky5. Missed polypectomy or patient refuse even smaller one(polypectomy of small polyps decreases the cancer incidence up to 70%.6.risk of age ,family history,smoking (the peak incidence of crc is 60 years of age ,the peak incidence of colorectal polyp discovering is 50 years of age ,this means 10 years time span for progression )
Hagitt criteria In the United States, the prevalence of adenomatous polyps found during colonoscopic evaluation ranges from 25 to 41%, and of these, 2 to 5% contain invasive malignancy. Endoscopic resection by polypectomy has been shown to be sufficient for management of certain polyps containing cancer.
Depth of invasion has been shown to correlate with the risk of lymph node metastasis. Other unfavorable histologic features include lymphovascular invasion, poor differentiation, inability to assess margin (piecemeal resection), and positive resection margin (<2 mm); these are important factors to consider in management. For these patients formal oncologic surgical resection is indicated. Polypectomy is usually performed during colonoscopy using snare polypectomy techniques. High-quality polypectomy is the complete excision of the polyp, which should include the entire stalk to its base. The submucosa of the bowel wall should be included to allow optimal histologic evaluation of the margins.
Level 0 indicates carcinoma in situ or intramucosal carcinoma. These lesions are not invasive, and therefore behave as benign adenomas due to an absence of lymphatics in the mucosal laye Level 0 Carcinoma in situ or intramucosal carcinoma. Not invasive. Level 1 Carcinoma invading through muscularis mucosa into submucosa, but limited to the head of the polyp. Level 2 Carcinoma invading the level of the neck of the adenoma. Level 3 Carcinoma invading any part of the stalk . Level 4 Carcinoma invading into the submucosa of the bowel wall below the stalk of the polyp, but above the muscularis propria.
Level 1 (above the junction between the adenoma and the stalk). Colorectal resection is not necessary if the line of resection of the stalk is free , routine follow-up is needed Level 2: carcinoma invading to the level of theneck of adenoma (the junction of adenoma and stalk).Surgical Resection is not necessary if the margin ofof the stalk is free and endoscopic follow-up isneeded.
Level 3: carcinoma invading any part of the stalk.A free margin of resection precludes the necessarilyfor any formal colorectal resection. Level 4: carcinoma invading the submucosa ofbowel wall below the stalk of the polyps but above the muscular propria. This is invasive cancer and a formalbowel resection is necessary, By definition all sessile polyps with invasive carcinoma are level 4. Hence, resection of bowel wall is indicated.
Colonoscopy surveillance and surveillanceintervals for colorectal polyps polyp sized less than 1 cm detected on colonoscopy ,otherwise normal ,h/p of this polyp was hyperplastic _go home and colonoscopy repeated after 10 years . If the polyp was large sessile ,complete excision done this patient need colonscopy follow up after 3_months Resectional polypectomy of malignant non invasive polyp __need follow up colonscopy after 12 months ,after this period as for ordinary adenoma Resectional polypectomy of high grade dysplasia _colonscopy repeated after 3 months if normal repeated at 1 year if normal 5 years Resected of Single tubular adenoma less than 1 cm no need for follow up
Resection of adenoma +3 polyps +previous h/o other cancer __need colonscopy every 5 years For patient who have had surgical resection of colon cancer need follow up with colonscopy every 6 months for the initial 2 years Low risk (size <1cm,no.1-2 )repeated after 5 years Intermediated risk (size >1cm ,no. 3-4 ) :after 3 years High risk(>1cm ,no. more than 5 ) : after one year N.b the three risk degrees are exchangable .
References :Current medical diagnosis and treatment 2008Muir`s textbook of pathologyNms surgery (fifth edition)Website adress : clinics in colon and rectalSurgery .