Podcast
Questions and Answers
What is the most common cause of ischemic colitis?
What is the most common cause of ischemic colitis?
Which area of the colon is typically affected by ischemic colitis?
Which area of the colon is typically affected by ischemic colitis?
Which of the following symptoms characteristically improves with defecation in irritable bowel syndrome?
Which of the following symptoms characteristically improves with defecation in irritable bowel syndrome?
What is a common symptom of ischemic colitis following an infarction?
What is a common symptom of ischemic colitis following an infarction?
Signup and view all the answers
What dietary change may improve symptoms in irritable bowel syndrome?
What dietary change may improve symptoms in irritable bowel syndrome?
Signup and view all the answers
Which characteristic is associated with the greatest risk for progression from adenoma to carcinoma?
Which characteristic is associated with the greatest risk for progression from adenoma to carcinoma?
Signup and view all the answers
Which gene mutation is implicated in increasing the formation of adenomatous polyps in both sporadic and germline cases?
Which gene mutation is implicated in increasing the formation of adenomatous polyps in both sporadic and germline cases?
Signup and view all the answers
Which colonic polyp type is most commonly found in the left colon, specifically the rectosigmoid region?
Which colonic polyp type is most commonly found in the left colon, specifically the rectosigmoid region?
Signup and view all the answers
What major preventive measure is used for patients diagnosed with Familial Adenomatous Polyposis (FAP)?
What major preventive measure is used for patients diagnosed with Familial Adenomatous Polyposis (FAP)?
Signup and view all the answers
Gardner syndrome is characterized by adenomatous polyps and what other condition?
Gardner syndrome is characterized by adenomatous polyps and what other condition?
Signup and view all the answers
Study Notes
Ischemic Colitis
- Occurs when there is ischemic damage to the colon, typically at the splenic flexure (watershed area of the superior mesenteric artery [SMA])
- Atherosclerosis of SMA is the primary cause of ischemic colitis
- Presents with postprandial pain and weight loss, which can progress to infarction characterized by pain and bloody diarrhea
Irritable Bowel Syndrome
- Characterized by relapsing abdominal pain with bloating, flatulence, and changes in bowel habits (diarrhea or constipation)
- Symptoms typically improve with defecation, and are commonly seen in middle-aged females
- No identifiable pathologic changes are seen in irritable bowel syndrome
- Disturbed intestinal motility is thought to contribute to the development of irritable bowel syndrome
- Increasing dietary fiber may help alleviate symptoms
Colonic Polyps
- Raised protrusions of the colonic mucosa, with hyperplastic and adenomatous polyps being the most common types
-
Hyperplastic polyps: due to hyperplasia of glands, classically show a serrated appearance on microscopy
- Most common type, usually arise in the left colon (rectosigmoid)
- Benign, with no malignant potential
-
Adenomatous polyps: due to neoplastic proliferation of glands
- Second most common type
- Benign, but premalignant, may progress to adenocarcinoma through the adenoma-carcinoma sequence
-
Adenoma-carcinoma sequence: describes the molecular progression from normal colonic mucosa to adenomatous polyp to carcinoma
- APC mutations (sporadic or germline) increase the risk for the formation of polyp
- K-ras mutation leads to the formation of polyp
- p53 mutation and increased expression of COX allow for progression to carcinoma; aspirin impedes progression from adenoma to carcinoma
Screening and Removal
- Performed by colonoscopy and testing for fecal occult blood
- Goal is to remove adenomatous polyps before progression to carcinoma
- Polyps are usually clinically silent, but can bleed
- All polyps are removed and examined microscopically during colonoscopy
- Greatest risk for progression from adenoma to carcinoma is related to size greater than 2 cm, sessile growth, and villous histology
Familial Adenomatous Polyposis (FAP)
- Autosomal dominant disorder characterized by 100s to 1000s of adenomatous colonic polyps
- Due to inherited APC mutation (chromosome 5), increases propensity to develop adenomatous polyps throughout colon and rectum
- Colon and rectum are removed prophylactically; otherwise, almost all patients develop carcinoma by 40 years of age
Associated Syndromes
-
Gardner syndrome: FAP with fibromatosis and osteomas
- Fibromatosis: non-neoplastic proliferation of fibroblasts, arises in retroperitoneum (desmoid) and locally destroys tissue
- Osteoma: benign tumor of bone that usually arises in the skull
- Turcot syndrome: FAP with CNS tumors (medulloblastoma and glial tumors)
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on two important gastrointestinal topics: Ischemic Colitis and Irritable Bowel Syndrome. Learn about their causes, symptoms, and effects on the digestive system.
