Mehlman. Polyp conditions+colorectal 03-05 (3) Flashcards
Lynch syndrome (HNPCC).
Mismatch repair genes MSH2/6, MLH1, PMS2.
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Lynch syndrome (HNPCC). mutations cause what?
microsatellite instability.
Lynch syndrome (HNPCC).
Hereditary non-polyposis colorectal cancer.
Lynch syndrome (HNPCC). assoc with what cancer?
Its colonic polyps/cancer; also associated with gynecologic cancer.
Lynch syndrome (HNPCC). when start colonoscopy?
Start colonoscopy at age 20-25, then do every 1-2 years.
Familial Adenomatous Polyposis (FAP); chromosome 5; AD.
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FAP. Hundreds to thousands of polyps on colonoscopy; 100% cancer risk.
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FAP. when start colonoscopy?
Start colonoscopy at age 10-12 and do every 1-2 years. Then do prophylactic proctocolectomy at age 18 (on NBME).
FAP + soft tissue (e.g., lipoma) or bone tumors (e.g., of the skull) = syndrome?
Gardner syndrome.
FAP + CNS tumors = syndrome?
Turcot syndrome
Peutz-Jeghers. definition?
Combo of perioral melanosis and HAMARTOMATOUS colonic polyps.
Peutz-Jeghers. screening?
Start colonoscopy at age 8, then do every 1-2 years.
Juvenile polyposis. Shows up on a 2CK NBME.
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Juvenile polyposis.
Q will tell you there’s a teenager (i.e., juvenile, LOL!) with intermittent bleeding
per rectum + colonoscopy shows scattered polyps + biopsy shows “dilated, cystic,
mucus-filled glands with abundant lamina propria and inflammatory infiltrates”
-> answer = juvenile polyposis.
Only question I’ve seen on it, but it’s on new 2CK NBME so I have to mention it.
Hyperplastic polyps.
All you need to know is these are not pre-cancerous / have no dysplasia.
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Tubulovillous.
Dysplastic polyps that precede full-blown colorectal cancer are classically either tubular or villous, AND either pedunculated or sessile.
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Tubulovillous.
Villous vs tubular?
villous is worse
Tubulovillous.
Sessile vs pedunculated?
Sessile is worse than pedunculated.
Tubulovillous. the worst polyp?
Villous sessile
Tubulovillous. the best polyp?
Tubular pedunculated
Tubulovillous. Sessile means flat; pedunculated means “sticks out.”
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Tubulovillous.
Polyps can have mixed chacteristics and hence be tubulovillous
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Tubulovillous.
USMLE will give you a random 65-year-old with a polyp + show you a pic + ask you what it is answer = “tubular polyp.” Student freaks out and says, “Wait, we need to know polyp pics??” No. The big picture
concept is that older people who get colorectal cancer will have tubular, villous, or tubulovillous polyps as I just said. Wrong answers would be things like hamartomatous, juvenile, and hyperplastic. You can just eliminate to get there
without even knowing the image.
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Tubulovillous.
2CK wants you to know that patients with HISTORY of dysplastic polyps need
repeat colonoscopies every 2-5 years, depending on size/morphology of polyp(s).
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Colorectal.
first KRAS, then PTEN, then DCC, then TP53.
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Colorectal. If they tell you a colon cancer has metastasized and force you to choose a gene that’s mutated?
TP53 for p53 protein
Colorectal. - If they tell you a polyp is seen and there is no evidence of invasion of the stalk, what mutation?
choose KRAS
Colorectal. Can cause what complication in pelvis?
Can cause colovesicular fistulas, where a passageway develops between the GI tract and bladder, leading to UTIs and mixed enteric flora in the urine.
Colorectal. Colovesicular fistulas are also assesed for diverticulosis.
This is also assessed for diverticulosis on 2CK and seems to be a new diagnosis USMLE likes. This could also be due to Crohn, in theory, but I haven’t seen it on NBMEs yet.
Colorectal. what causes endocarditis?
Can cause Strep bovis endocarditis. Obscure, but rare point assessed on USMLE.
