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21 Cards in this Set

  • Front
  • Back
Major types of intestinal polyps
1. hyperplastic
2. hamartomatous
3. inflammatory
4. lymphoid
5. adenomatous
Hyperplastic polyps
-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
Hamartomatous Polyps
-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
Inflammatory polyps (pseudopolyps)
-represent inflamed regenerating tissue surrounded by ulceration
- most associated with those who have inflammatory bowel disease
Lymphoid Polyps
these are a large but normal variants of intramucosal lymphoid tissue
adenomatous polyps (adenomas)
-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
tubular adenoma
-comprised of tubular epithelial glands
villous adenoma
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
tubulovillous adenoma
has both villous and tubular features
Peutz-Jeghers Syndrome
-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
Familial adenomatous polyposis (FAP)
-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
Gardeners Syndrome
-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
Turcots Syndrome
- a form of classic FAP
- classic FAP colon polyps + malignant brain tumors
-high risk of polyps becoming a colon cancer
- autosomal dominant
Hereditary Nonpolyposis Colorectal Cancer (HNPCC) Syndrome
- 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
Colon Cancer
-most occur sporadically
-most arise from adenomas (adenomatous polyps)
- use of NSAIDs and asprin have been shown to be protective
2 molecular mechanisms for colon cancer
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
Risk factors predispose one to colon cancer
1. excessive dietary caloric intake
2. high refined carbohydrate diet
3. intake of red meat
4. reduced consumption of dietary fiber
Right colon cancer
cause iron-deficiency anemia (with concomitant fatigue and weakenss) and + hemoccult stool; no stool changes are noted
Left colonic cancers
cause + hemoccult stool, change in bowel habits, and crampy left lower quadrant discomfort or tenesmus; pencil stools may also be produced
>50 yrs with iron deficiency anemia
must be worked up to rule out colon carcinoma
preferred metastatic sites for colon cancer
liver and lungs