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21 Cards in this Set
- Front
- Back
Major types of intestinal polyps
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1. hyperplastic
2. hamartomatous 3. inflammatory 4. lymphoid 5. adenomatous |
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Hyperplastic polyps
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-the most common colonic polyp (90% of all polyps)
-most common in those in their 50s and 60s -due to decreased epithelial cell turnover in the bowel, resulting in the accumulation of mature cells on the surface - have little to no risk for malignant transformation |
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Hamartomatous Polyps
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-represent malformations of the glands and stroma of the epithelium, causing overgrowth of mature tissue natural to the area
- have little to no risk for malignant transformation -can occur sporadically or in association with Peutz-Jeghers Syndrome |
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Inflammatory polyps (pseudopolyps)
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-represent inflamed regenerating tissue surrounded by ulceration
- most associated with those who have inflammatory bowel disease |
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Lymphoid Polyps
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these are a large but normal variants of intramucosal lymphoid tissue
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adenomatous polyps (adenomas)
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-are neoplastic - therefore, are pre-malignant, acting as a precursor lesion for invasive colorectal carcinoma
- all arise from proliferative dysplasia of epithelial cells lining the colon -3 subtypes : tubular adenoma, villous adenoma, tubulovillous adenoma |
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tubular adenoma
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-comprised of tubular epithelial glands
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villous adenoma
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has villous (fnger like projections); when these are >4cm in diameter, they are the polyps with the highest risk for malignant transformation
- they are most common to the rectum and rectosigmoid colon, and usually cause gross rectal bleeding, hypokalemia and hypoproteinemia |
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tubulovillous adenoma
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has both villous and tubular features
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Peutz-Jeghers Syndrome
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-an inherited autosomal dominant hamartomatous polyp disorder that is familial polyposis syndrome of the entire bowel
-hamartomatous polyps + spotted melanin hyperpigmentation of lips, palms, and soles -polyps have very low cancer potential -however, the risk of colon cancer (and other cancers) not related to these polyps is greater than that of the general population |
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Familial adenomatous polyposis (FAP)
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-due to loss of the tumor suppressor gene, APC
- once polyps develop, there is almost a 100% chance of colon cancer development - typically patients develop 500-2500 polyps that carpet the colon -all polyps are adenomatous -autosomal dominant |
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Gardeners Syndrome
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-a form of classic FAP
-classic FAP colon polyps + benign mandible and skull tumors + epidermal cysts + high risk for abnormal dentition -nearly 100% chance of polyps developing into a colon cancer -autosomal dominant |
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Turcots Syndrome
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- a form of classic FAP
- classic FAP colon polyps + malignant brain tumors -high risk of polyps becoming a colon cancer - autosomal dominant |
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Hereditary Nonpolyposis Colorectal Cancer (HNPCC) Syndrome
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- also known as lynch syndrome
-autosomal dominant -due to defective DNA mismatch repair genes; associated with microsatellites -increased risk for colon cancer and multiple other cancers, including cancer of the stomach, liver, brain, prostate, skin, biliary ducts, small intestine, and especially the endometrium and ovary -cancer development tends to not arise from adenomatous polyps - colonic malignancies occur in multiple sites and are not typically formed within or in association with adenomas |
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Colon Cancer
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-most occur sporadically
-most arise from adenomas (adenomatous polyps) - use of NSAIDs and asprin have been shown to be protective |
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2 molecular mechanisms for colon cancer
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1. APC/Beta-catenin pathway: the APC gene (a tumor suppressor gene) becomes inactivated
2. k-Ras (an oncogene) is mutated and p53 (a tumor suppressor gene) is inactivated |
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Risk factors predispose one to colon cancer
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1. excessive dietary caloric intake
2. high refined carbohydrate diet 3. intake of red meat 4. reduced consumption of dietary fiber |
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Right colon cancer
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cause iron-deficiency anemia (with concomitant fatigue and weakenss) and + hemoccult stool; no stool changes are noted
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Left colonic cancers
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cause + hemoccult stool, change in bowel habits, and crampy left lower quadrant discomfort or tenesmus; pencil stools may also be produced
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>50 yrs with iron deficiency anemia
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must be worked up to rule out colon carcinoma
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preferred metastatic sites for colon cancer
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liver and lungs
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