6/7 UWorld Flashcards
Symptoms of carcinoid syndrome
- Symptoms = BFDR
- Bronchospasm
- Flushing
- Diarrhea
- Right-sided heart disease/murmur
What is angiodysplasia?
- Tortuous dilation of vessels within the bowel, leading to hematochezia
- Unexplained GI bleeding and anemia
What is proctitis
- Inflammation of perianal region and rectum
- Usually due to fecal matter in the area for an extended period of time
- Also associated with ulcerative colitis
Describe the progression from adenoma to carcinoma in colorectal cancer
- Order of events = AK=53
- Normal colon
- = APC (adenomatous polyposis coli) gene mutation (loss of APC)
- Colon at risk for polyps
- = KRAS mutation (oncogene)
- Development of polyps/adenoma
- = p53 mutation (loss of tumor suppressor)
- Progression to carcinoma
What is Turcot syndrome
- FAP + malignant CNS tumor (medulloblastoma)
- THINK: TURcot = TURban
What is the defect in hereditary nonpolyposis colorectal cancer (HNPCC)
Aka Lynch Syndrome
Defect in DNA mismatch repair (MMR)
Most common location of diverticulitis
Sigmoid colon (LLQ pain)
Most common location of Crohn’s
Terminal ileum; rectal sparing
Vs. UC which can only affect the colon and rectum is always involved
Crohn’s vs. Ulcerative colitis
Histology
Crohn - noncaseating granulomas with lymphoid aggregates
UC - crypt abscesses with neutrophils
Crohn’s vs. UC - X-ray imaging
Crohns:
- Cobblestone mucosae
- Creeping fat
- Strictures = “string sign” appearance
UC:
- Loss of haustra = “lead pipe” appearance
Describe excretion of bilirubin (urobilinogen, stercobilin, and urobilin)
- Colonic bacteria converts bilirubin to urobilinogen
- Most (80%) Urobilinogen is oxidized to stercobilin and excreted in the stool – makes stool brown
- Small amount (20%) of urobilinogen is reabsorbed by the gut
- 90% Enters mesenteric veins and goes back into the liver and into bile – enterohepatic circulation
- Tiny amount (10%) of reabsorbed urobilinogen is converted to urobilin and excreted in the urine – makes urine yellow
Describe primary sclerosing cholangitis (histology, imaging, complications)
- Unknown cause
- Concentric fibrosis of the intra- and extra-hepatic bile ducts (“onion skin” fibrosis)
- Contrast imaging will show “beaded” appearance due to alternating fibrotic and dilated regions
- Mostly occurs in men around age 40
- Associated with (+) pANCA and Ulcerative colitis
- Can lead to secondary biliary cholangitis
- Increased risk for cholangiocarcinoma
Describe the source of bilirubin
- Bilirubin metabolism:
- Hemoglobin broken down into heme and globin
- Heme then broken down into iron and protoporphyrin
- Protoporphyrin converted into unconjugataed bilirubin (water insoluble)
- UCB binds to albumin to be brought to the liver
- Liver conjugates UCB into CB (water soluble)
- UDP glucuronyl transferase (UGT) is the enzyme in the hepatocytes that conjugates bilirubin
- CB dumped into bile canaliculi to be sent to the gallbladder
What is the cause and histology of Primary biliary cirrhosis (PBC)
- Autoimmune destruction of intra-hepatic bile ducts
- Associated with other autoimmune conditions
- Lymphocytic infiltrate + granulomas
What is Charcot’s triad of cholangitis?
- Inflammation/infection of the biliary tree
- Charcot’s triad:
- Jaundice
- Fever
- RUQ pain
- Reynold’s pentad:
- Jaundice, fever, RUQ pain, Hypotension, AMS