10.8 Colon and Colorectal Carcinoma Flashcards
Hirschsprung Disease
Defective relaxation and peristalsis of the rectum and distal sigmoid colon
What is Hirschspring Disease associated with?
Down Syndrome
What is the cause of Hirschsprung?
Failure of the ganglion cells to descend - lacking in the rectum and the sigmoid
What are the clinical features of Hirschsprung?
Failure to pass meconium with massive dilation of the the bowel proximal to obstruction with risk for rupture
Colonic Diverticula
Outpouchings of mucosa and submucosa through the muscularis propria - pseudo-diverticula - often on the left colon
What is the cause of the colonic diverticula?
Increased wall stress from straining and constipation
What is the most common location of the colonic diverticula?
Sigmoid Colon
Angiodysplasia
Acquired malformation of mucosal and submucosal capillary beds - usually in the right colon and cecum from high wall tension
Hereditary Hemorrhagic Telangiectasia
Autosomal dominant disorder that results in thin walled vessel in the nasopharynx and the GI tract - bleeding can occur
Ischemic Colitis
Ischemic damage to the colon - usually at the splenic flexure
What is the most common cause of ischemic colitis?
Atherosclerosis of the SMA
Irritable Bowel Syndrome
Relapsing abdominal pain with bloating flatulence and change in bowel habits that improves with defecation
Who is the typical patient of irritable bowel syndrome?
Middle aged females
Colonic Polyps
Raised protrusions of the colonic mucosa
What are the 2 most common types of colonic polyps?
- Hyperplastic
- Adenomatous
Hyperplastic Polyp
“Serrated” and due to hyperplasia of the glands - benign with NO malignant potential
Where do hyper plastic polyps tend to arise?
Left Colon - they are the most common polyps
Adenomatous Polyp
Neoplasm of glands and is benign but premalignant and can progress to adenocarcinoma
Adenoma - Carcinoma Sequence
APC mutation leads to increased risk with KRAS mutation leading to polyp formation and p53 mutation leading to carcinoma
What chromosome is APC found on?
Chromosome 5
How does aspirin protect against adenocarcinoma sequence?
It decreases the COX levels which are needed for adenocarcinoma formation
What are the risks for a polyp to progress to carcinoma?
- Size greater than 2 cm
- Sessile growth
- Villous histology
Familial Adenomatous Polyposis
Autsomal dominant disorder with many polyps and is due to an inherited APC gene
Gardner Syndrome
FAP disorder with fibrzomatosis and osteomas
Turcot Syndrome
FAP with CNS tumors (medullooblastoma and glial tumors)
Juvenile Polyp
Hamartomatous polyps that are benign and arise in children - usually solitary rectal polyp
Juvenile Polyposis
Multiple juvenile polyps in the stomach and in the colon
Peutz-Jeghers Syndrome
Hamartomatous polyps throughout the GI tract - autosomal dominant and increases the risk for colorectal, breast and GYN cancer
What is the most common pathway from which colorectal cancer arises?
Adenoma-Carcinoma Sequence
What is the second most common pathway by which colon cancer arises?
Microsatellite Instability
Microsatellite Instability Pathway
Mutation in DNA repair enzymes that leads to them being unstable and accumulating mutations
Hereditary Nonpolyposis Colorectal Carcinoma
Due to the MSI pathway with an inherited mutation in the DNA mismatch repair enzymes that will have increased risk for colorectal, ovarian and endometrial carcinoma - cancer arises at an early age and is usually right sided
What are some of the other risks for colorectal carcinoma?
- Ulcerative Colitis
- Peutz-Jehger Syndrome
How is CRC screened for?
Colonoscopy and fecal occult blood testing
Describe left sided CRC.
Napkin ring lesion with LLQ pain, decreased stool caliber and blood streaked stool
Describe right sided CRC.
Raised lesion with iron deficiency anemia and vague pain
What side CRC is associated with the adenoma-carcinoma sequence?
Left Sided
What side CRC is associated with MSI?
Right Sided
What are patients with Streptococcus bovis endocarditis at increased risk of?
CRC - do a colonoscopy
What is the most common site of metastasis of CRC?
Liver
What is the tumor marker of CRC?
CEA - used for assessing treatment response
