8. Disorders of the gallbladder & extrahepatic bile ducts

Question 1

Disorders of the gall bladder and extrahepatic bile ducts

Answer 1

1. Choledochal Cyst
2. Cholelithiasis
3. Cholecystitis

Question 2

Definition of Choledochal Cyst

Answer 2

Congenital dilations of the common bile duct

Question 3

Epidemiology and associations of choledochal cyst

Answer 3

1. Most commonly presents in children before age 10 as
   non-specific symptoms of jaundice & recurrent abdominal pain
2. Sometimes occur in conjunction with Caroli disease
   (congenital cystic dilations of intrahepatic tree)

Question 4

Morphology of choledochal cyst

Answer 4

Segmental or cylindrical dilations of common bile duct

Question 5

Pathological Effects & Complications of choledochal cyst

Answer 5

1. Predisposition to stone formation, resulting in biliary obstruction & associated complications:
   - Cholangitis
   - Cholangitic abscess
   - Secondary biliary cirrhosis
2. Rupture, leading to GI bleeding
3. Increased risk of bile duct carcinoma

Question 6

Definition of Cholelithiasis

Answer 6

Commonly known as gallstones, formed within the gallbladder; in strict technical terms, stones found within the intra- or extrahepatic bile ducts are called choledocholithiasis

Question 7

Epidemiology & Associations of cholelithiasis

Answer 7

1. Forty (years old)
2. Female
3. Fertile (estrogenic influence, including pregnancy &
   contraceptive use, due to increase in uptake & biosynthesis of cholesterol in the liver leading to secondary increase in biliary cholesterol excretion)
4. Fatty (associated with metabolic syndrome)

Question 8

Types of gallstones

Answer 8

1. Pure cholesterol stone
   - Composed of cholesterol
   - Yellow, finely granular, hard
   - Radiolucent
2. Pure pigment stone
   - Composed of calcium bilirubinate (unconjugated)
   - Black (sterile) or brown (infected), friable
   - Black mostly radiopaque, brown mostly radiolucent
3. Pure calcium carbonate stone
4. Mixed stones, combined stones

Question 9

Pathogenesis of cholesterol stones

Answer 9

1. Supersaturation of cholesterol
   - When cholesterol concentration exceed the solubilization capacity of bile salts & lecithin
   - May be due to excessive biliary cholesterol or insufficient bile salt formation
2. Hypomotility of the gallbladder
   - Promotes cholesterol nucleation
3. Cholesterol nucleation
   - Formation of insoluble cholesterol crystals
4. Accretion of nucleated cholesterol crystals to form stones
   - Promoted by mucus hyper secretion & gallbladder hypomotility

Question 10

Risk factors for pigment stones

Answer 10

1. Hemolytic anemias
   - Increases biliary bilirubin excretion
2. Biliary tract infection
   - Release of microbial beta-glucuronidases prematurely deconjugates conjugated bilirubin in biliary secretions
   - Results in the accumulation of large amounts of less soluble unconjugated bilirubin within biliary tree
3. Ascaris lumbricoides, liver flukes

Question 11

Pathological effects & complications of gallstones

Answer 11

1. Cholecystitis
   - Empyema (gallbladder converted to a bag of pus)
   - Hydrops of gallbladder (chronically obstructed atrophic gallbladder)
2. Common bile duct obstruction, leading to:
   - Obstructive jaundice
   - Ascending cholangitis
   - Secondary biliary cirrhosis
3. Cholecystointestinal fistula formation
   - As inflammation of gallbladder can result in formation of adhesions with intestine, which is converted to a fistula over time
   - Large stones can directly enter the gut, causing intestinal obstruction
4. Bouveret syndrome (gallstone ileus)
   - Direct erosion of a large gallstone through gallbladder into GI tract
   - Results in gastric outlet obstruction
5. Carcinoma gallbladder

Question 12

Definition of Cholecystitis

Answer 12

Inflammation of the gallbladder; may be acute, chronic, acute-on-chronic

Question 13

Causes and pathogenesis of acute cholecystitis

Answer 13

1. Acute calculous cholecystitis
   - Due to obstruction by gallstone
   - Mucosal phopholipases hydrolyse lecithins to lysolecithins, which disrupt normally protective mucus layer
   - This exposes the mucosa to direct detergent action of bile salts, resulting in inflammation
   - Gall bladder dysmobility then develops, leading to distension & increase in intraluminal pressure
   - Blood flow is then compromised, leading to ischemic damage to the gallbladder
   - Bacterial infection typically imposed upon initial mechanical & chemical factors
2. Acute acalculous cholecystitis
   - No gallstones involved in pathogenesis
   - Causes/risk factors: sepsis with hypotension, immunosuppression, major trauma & burns, diabetes mellitus, Salmonella Typhi infection

Question 14

Pathological effects & complications of cholecystitis

Answer 14

1. Pericholecystic & subdiaphragmatic abscess
2. Peritonitis
3. Ascending cholangitis & liver abscess
4. Septicemia

Question 15

Morphology of acute cholecystitis

Answer 15

1. [Grossly]
   - Enlarged & tense
   - Fibrinosuppurative serosal surface
2. [Histologically]
   - Acute inflammatory infiltrate

Question 16

Causes and pathogenesis of chronic cholecystitis

Answer 16

1. Sequel to repeated bouts of acute cholecystitis

2. Mostly associated with cholelithiasis

Question 17

Morphology of chronic cholecystitis

Answer 17

1. [Grossly]
   - Thickened, contracted wall
   - Associated with obstructive calculi
2. [Histologically]
   - Chronic inflammatory infiltrate
   - Muscular hypertrophy
   - Rokintansky-Aschoff sinuses
   (mucosal outpouchings through wall due to bile being forced through areas of weaker musculature secondary to increased intraluminal pressure due to muscular hypertrophy)
   - Dystrophic calcification (gives rise to a porcelain gallbladder)