Pathology of the Gallbladder, Extrahepatic Biliary Tract, and Pancreas Flashcards
What are bile salts and lecithins? Are they water soluble or insoluble?
- Bile salts - bile acids made from cholesterol, conjugated to glycine or taurine. Water soluble, and the primary component of bile
- Lecithins - phosphatylcholine, water-insoluble
Other than bile salts and lecithins, what are the other components of bile?
Cholesterol
Proteins - probably acting as the nidus for stone formation
Bilirubin
How does bilirubin get made and transported to the liver?
Made in reticuloendothelial system (i.e. spleen)
Heme -> biliverdin = open chain form of heme porphyrin ring
Unconjugated bilirubin made from biliverdin, and transported via albumin in blood (UCB is water insoluble, needs to be conjugated)
What is the fate of bilirubin once it enters the intestine?
Bacteria in the gut deconjugate it to urobilinogen.
Urobilinogen can be excreted in stool after being made into stercobilin -> gives the stool its brown color.
Some urobilinogen is reabsorbed -> can be excreted again in bile, or transported to kidneys where it is oxidized to urobilin -> gives the urine its yellow color.
What is the fate of bile salts when they enter the intestines?
They are partially deconjugated from glycine / taurine
95% of these will be reabsorbed in the terminal ileum (same site as B12), will return via portal vein, and be used against after conjugation (used 20 times on average)
What is the most common congenital anomaly of the gallbladder?
Phrygian cap -> fundus (body, as opposed to neck and cystic duct) of the gallbladder folded inward
What are choledochal cysts and what are the possible complications?
Dilatations or outpouchings of the COMMON bile duct (think choledocholithiasis)
possible complications:
- choledocholithiasis
- cholangitis - infection of pouches
- biliary tract obstruction
- bile duct carcinoma
What are the causes of biliary atresia?
Failure to form (rarer) or early destruction (within 2 mo of birth) of extrahepatic biliary tree (probably due to inflammation from infection leading to stricture and destruction of the bile duct)
What are the consequences of biliary atresia?
Bile ducts -> progressive fibrosis may cause extrahepatic to become intrahepatic atresia
Liver - cholestasis causes portal tract infiltration, fibrosis, and bile duct proliferation = secondary biliary cirrhosis
What is the treatment for biliary atresia?
Early surgical correction if restricted to extraheptic bile ducts
Liver and bile duct transplant if intrahepatic spread
What are the types of gallstones and which one predominates in the US?
- Cholesterol - predominates in US
2. Pigment (bilirubin)
What is the pathogenesis of cholesterol stones?
Supersaturation of bile with cholesterol due to:
1. Increased biliary secretion of cholesterol
or
2. Decreased secretion of bile salts to solubilize
+ bile stasis in gallbladder = increased cholesterol stone nucleation + excess mucin (produced by epithelium in gallbladder) = stones
What are the risk factors for cholesterol stone formation?
- Developed countries
- Native American ethnicity
- Increased secretion of bile - advanced age, estrogen (obesity, women, OCPs, pregnancy)
- Gallbladder hypomotility - rapid weightloss, fasting, or neurogenic
How do cholesterol stones appear grossly and are they radio-opaque or translucent?
Can be pure cholesterol -> clear to yellow, rarer
Mixed stones -> >50% cholesterol and bile pigments, most common
They are radiolucent, must be detected with ultrasound
What gallbladder pathology is commonly seen with choesterol stones and what is the cause? How does it appear grossly and microscopically?
Cholesterolosis - aggregates of foamy macrophages within the subepithelium of gallbladder. Grossly -> little yellow deposits within the mucosa.
Increased bile cholesterol increases cholesterol absorption by gallbladder mucosa -> accumulate in subepithelium
What is the pathogenesis of pigment gallstones?
Increased UNconjugated bilirubin in bile which is not water soluble -> aggregation of calcium salts, mucin, and cholesterol
What are the risk factors for pigment gallstones?
- Chronic hemolysis -> increased biliary excretion of conjugated bilirubin, and a small percentage always becomes unconjugated
- Biliary tract infections -> microbial deconjugation of bile acids
- Gallbladder hypomotility -> thickens bile
What are the two morphological types of pigment stones? What causes them? Are they radio-opaque or translucent?
Black - occur in chronic hemolysis -> majority are radio-opaque from complexing with calcium. Multiple and smooth.
Brown - occur in biliary tract infections -> soft and soapy, radiotranslucent
What are the four F’s of cholelithiasis risk factors?
Female
Fat
Fertile (pregnant)
Forty
What are the possible complications of cholelithiasis?
- *Acute cholecystitis
- Hydrops of gallbladder due to chronic obstruction
- Choledocholithiasis -Obstruction of the common bile duct
- Chronic cholecystitis
- Gallstone ileus
- Carcinoma of the gallbladder
What are some severe variants of acute cholecystitis? Include also one complication of an ulcer forming during this time.
- Empyema of gallbladder - bag of pus
- Gangrene and perforation - if ischemia is very severe, hemorrhagic necrosis of gallbladder wall
Ulceration:
3. Fistula tracts -> ulceration forms in wall which allows attachment to nearby loop of duodenum
What are the possible complications of choledocholithiasis?
- Cholestasis with secondary biliary cirrhosis
- Ascending cholangitis with possible liver abscess formation
- Pancreatitis - if stone is wedged right before ampulla of Vater
What is a gallstone ileus and how does it occur?
Large stone plugging the lumen of the duodenum
-> occurs due to formation of a fistula tract thru gall bladder, allowing stones to leak into duodenum and obstruct lumen
What is the most common type of cholecystitis and its pathogenesis?
Calculous cholecystitis - obstruction of neck of gallbladder via a stone = retention of bile, gallbladder distention, and vascular compression in the wall (venous congestion, causing hemorrhagic infarct overtime)
What are the risk factors for the less common type of cholecystitis (acalculous)?
Critically ill patients - occurs without stone, due to hypomotility or hypoperfusion
- > Cystic duct obstruction by concentrated bile with excessive reabsorption due to dehydration and hypomotility
- > poor vascular perfusion (during shock)
- > bacterial infection
How will acute cholecystitis appear grossly? Microscopically?
Enlarged, erythematous gallbladder with thick edematous wall due to inflammation / hyperemia.
Dull serosal opacities, appearing whitish-yellow (pus), maroonish (blood), and greenish-black (bile)
Microscopically - acute inflammatory infitlrate with ulceration and necrosis