Colon - Pathoma Flashcards
What developmental disorder is Hirschsprung disease associated with?
Down Syndrome
What is the embryologic abnormality that causes Hirschsprung Disease?
congenital failure of ganglion cells to descend
What causes Colonic Diverticula?
- Related to wall stress
- associated with constipation and low fiber diet
- commonly seen in older adults
- Arise where vasa recta traverse musclularis propria ⇒ weak point in colonic wall
- sigmoid colon is most common location
What are the symptoms/complications of Colonic Diverticula?
- Sx: Usually asymptomatic
- Complications:
- Rectal bleeding (hematochezia)
- Diverticulitis
- Fistula
What is Angiodysplasia?
- Acquired malformation of mucosal and submucosal capillary beds
Where does Angiodysplasia most commonly arise? Why?
- Cecum and Right Colon
- due to high wall tension
How does Angiodysplasia typically present?
Hematochezia in an older adult
What is Hereditary Hemorrhagic Telangectasia?
- Autosomal dominant disorder resulting in thin-walled blood vessels
- especially in the nasopharynx and GI tract
- Rupture presents as bleeding
What is ischemic colitis?
ischemic damage to the colon
Where does ischemic colitis most often occur?
Splenic flexure
What is the most common cause of ischemic colitis?
Atherosclerosis of the Superior Mesenteric Artery
How does Ischemic Colitis typically present?
- Postprandial pain and weight loss
- increase energy requirements after meal
- Infarction presents as pain and bloody diarrhea
What GI wall layers contribute to Colonic Polyps?
raised protrusions of colonic mucosa
What is the most common type of Colonic Polyp?
Hyperplastic Polyp
What causes Hyperplastic Polyps?
- due to hyperplasia of glands
Where to hyperplastic polyps most commonly arise?
Left colon (rectosigmoid)
Are hyperplastic polyps benign or malignant?
Benign, with no malignant potential
What is the second most common type of colonic polyp?
Adenomatous polp
= neoplastic proliferation of glands
Are adenomatous polyps benign or malignant?
- Benign, but premalignant
- may progress to adenocarcinoma via the adenoma-carcinoma sequence
What is the Adenoma-Carcinoma Sequence?
- APC mutations (sporadic or germline, chroms. 5) increase risk for formation of polyp
- KRAS mutations lead to mutation of polyp
- p53 mutations and increased expression of COX allow for progression to carcinoma
What are the three key risk factors that tell you there is an increased theoretical risk of the progression from adenoma to carcinoma evaluated during colonoscopy?
- Risk for progression from adenoma to carcinoma
- related to size >2cm
- sessile growth (no stalk)
- villous histology
What is FAP?
- Autosomal dominant disorder → due to inherited APC mutation (chromosome 5)
- characterized by 100’s to 1,000’s of adenomatous colonic polyps
What is the prophylactic treatment for carcinoma in FAP patients?
Removal of colon and rectum
What syndrome is associated with the combination of FAP + fibromatosis + osteomas?
Gardner Syndrome
(fibromatosis = non-neoplastic proliferation of fibroblasts that is destructive)
(osteoma = benign tumor of bone)
What syndrome is associated with the combination of FAP + CNS tumors?
Turcot syndrome
(medulloblastoma and glial tumors)
What is a Juvenile Polyp?
Sporadic hamartomatous benign polyp that arises in children (<5 yoa)
How does a Juvenile polpy usually present?
Solitary rectal polyp that prolapses and bleeds
Does Juvenile Polyposis (multiple juvenile polyps in the stomach and colon) increase the risk of cancer?
Yes!
Large numbers of juvenile polyps increases the risk of progression to carcinoma
What syndrome is associated with hamartomatous polyps throughout the GI tract and mucocutaneous hyperpigmentation of the lips, oral mucosa, and genital skin?
Peutz-Jeghers Syndrome
What is the inheritance pattern of Peutz-Jeghers Syndrome? Risk?
- Autosomal dominant
- Increased risk for colorectal, breast, and GYN cancer
