Adenomatous colorectal cancer syndromes vs Hamartomatous polyposis syndromes
How to tell Adenomatous colorectal cancer syndromes and Hamartomatous polyposis syndromes apart when a board question makes them look alike.
FAP is innumerable APC adenomas; Lynch is MMR cancer with few polyps; Peutz-Jeghers is pigmented hamartomas; juvenile polyposis is bleeding juvenile hamartomas.
Side by side
Familial adenomatous polyposis has hundreds to thousands of adenomatous polyps from APC mutation; Lynch has early colon cancer with few polyps from mismatch repair defects.
Peutz-Jeghers has mucocutaneous pigmentation and hamartomatous polyps; juvenile polyposis has multiple juvenile hamartomatous polyps and bleeding/anemia risk.
APC pathway or mismatch repair failure drives adenoma-carcinoma progression and high colorectal cancer risk.
Hamartomatous polyp syndromes create disorganized benign tissue growth but can still carry GI and extraintestinal cancer risk.
APC mutation and numerous adenomas support FAP; microsatellite instability or MMR gene mutation supports Lynch syndrome.
Oral/lip pigmentation with hamartomatous polyps supports Peutz-Jeghers; multiple juvenile polyps with bleeding supports juvenile polyposis.
The trap
All raise colon cancer concern, but polyp number, histology, pigmentation, and DNA repair mechanism separate them.
The repair move
For inherited colon syndromes, sort adenoma versus hamartoma first, then use APC, MMR, pigmentation, or juvenile polyps.
Try a free question
CoreA teenager undergoes colonoscopy for rectal bleeding and is found to have hundreds of adenomatous polyps throughout the colon. Genetic testing shows a germline APC mutation. Which syndrome is most likely?
Show answer and explanation
Answer: A. Familial adenomatous polyposis. Hundreds to thousands of adenomatous polyps from APC mutation define FAP.
Why the other choices are tempting
- B. Lynch syndrome is mismatch repair-driven cancer risk with relatively few polyps.
- C. Peutz-Jeghers has hamartomatous polyps and mucocutaneous pigmentation.
- D. Juvenile polyposis has multiple juvenile hamartomatous polyps rather than countless adenomas.
- E. Sporadic hyperplastic polyps do not explain a germline APC carpeting-polyposis syndrome.
Flashcards
Tap a card to flip it.
What mutation points to familial adenomatous polyposis?
A germline APC mutation with hundreds to thousands of adenomatous polyps points to FAP.
What mechanism points to Lynch syndrome?
Mismatch repair defects with microsatellite instability point to Lynch syndrome.
Quick answers
What is the fastest way to tell Adenomatous colorectal cancer syndromes from Hamartomatous polyposis syndromes?
FAP is innumerable APC adenomas; Lynch is MMR cancer with few polyps; Peutz-Jeghers is pigmented hamartomas; juvenile polyposis is bleeding juvenile hamartomas.
What is the key clue for Adenomatous colorectal cancer syndromes?
Familial adenomatous polyposis has hundreds to thousands of adenomatous polyps from APC mutation; Lynch has early colon cancer with few polyps from mismatch repair defects.
What is the key clue for Hamartomatous polyposis syndromes?
Peutz-Jeghers has mucocutaneous pigmentation and hamartomatous polyps; juvenile polyposis has multiple juvenile hamartomatous polyps and bleeding/anemia risk.
What is the common trap with Adenomatous colorectal cancer syndromes vs Hamartomatous polyposis syndromes?
All raise colon cancer concern, but polyp number, histology, pigmentation, and DNA repair mechanism separate them.