Lynch syndrome (hereditary non-polyposis colorectal cancer, HNPCC) is confirmed by identifying germline mutations in mismatch repair genes. Which of the Amsterdam II criteria defines the minimum clinical requirement for suspecting Lynch syndrome?
- A Three or more relatives with colorectal cancer, two successive generations, one diagnosed before age 50, and familial adenomatous polyposis excluded ✓
- B Two first-degree relatives with colorectal cancer, one before age 40, KRAS mutation confirmed
- C More than 100 colonic polyps in a first-degree relative
- D One relative with synchronous colorectal and endometrial cancer before age 60
Correct answer: A. Three or more relatives with colorectal cancer, two successive generations, one diagnosed before age 50, and familial adenomatous polyposis excluded
Explanation
Amsterdam II criteria (3-2-1 rule): at least 3 relatives with Lynch-associated cancers (CRC, endometrial, small bowel, ureter/renal pelvis), at least 2 successive generations affected, at least 1 diagnosed before age 50, and FAP excluded. The Bethesda guidelines (revised) are broader for triggering MSI testing but Amsterdam II is the classic clinical diagnostic benchmark. Option B describes incorrect criteria with an irrelevant KRAS mention. More than 100 polyps defines FAP/AFAP. Option D describes a suspicious pattern but falls short of the formal criteria.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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