Cholangitis

Cholangitis

• Cholangitis is the term used to describe inflammation of the extrahepatic or intrahepatic bile ducts or both.
• There are two main types of cholangitis—pyogenic and primary sclerosing. While primary sclerosing cholangitis is discussed later with biliary cirrhosis pyogenic cholangitis is described below.

Read And Learn More: Systemic Pathology Notes

Pyogenic Cholangitis

• Cholangitis occurring secondary to obstruction of a major extrahepatic duct causes pyogenic cholangitis.
• Most commonly, the obstruction is from impacted gallstones other causes are carcinoma arising in the extrahepatic ducts, carcinoma head of the pancreas, acute pancreatitis and inflammatory strictures in the bile duct.
• Bacteria gain entry to the obstructed duct and proliferate in the bile. The infection spreads along the branches of the obstructed duct and reaches the liver, termed ascending cholangitis.
• The common infecting bacteria are enteric organisms such as E. coli, Klebsiella and Enterobacter.

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Morphologic Features: The affected ducts show small beaded abscesses accompanied by bile stasis along their course and larger abscesses within the liver.

• The abscesses are composed of acute inflammatory cells which in time are replaced by chronic inflammatory cells and enclosed by fibrous capsules.

Pyogenic Liver Abscess

• Most liver abscesses are of bacterial (pyogenic) origin; less often they are amoebic, hydatid and rarely actinomycotic.
• Pyogenic liver abscesses have become uncommon due to improved diagnostic facilities and the early use of antibiotics.
• However, their incidence is higher in old age and in immunosuppressed patients such as those with AIDS, transplant recipients and those on intensive chemotherapy.

Pyogenic liver abscesses can occur by the following modes of entry:

1. Ascending cholangitis through ascending infection in the biliary tract due to obstruction e.g. gallstones, cancer, sclerosing cholangitis and biliary strictures.
2. Portal pyaemia by means of the spread of pelvic or gastrointestinal infection resulting in portal pylephlebitis or septic emboli examples from appendicitis, empyema of the gallbladder, diverticulitis, regional enteritis, pancreatitis, infected haemorrhoids and neonatal umbilical vein sepsis.
3. Septicaemia through spread by the hepatic artery.
4. Direct infection resulting in solitary liver abscess example from an adjacent perinephric abscess, secondary infection in amoebic liver abscess, metastasis and formation of haematoma following trauma.
5. Iatrogenic causes include liver biopsy, percutaneous biliary drainage and accidental surgical
   trauma.
6. Cryptogenic from unknown causes, especially in the elderly.
7. The commonest infecting organisms are gram-negative bacteria chiefly E. coli; others are Pseudomonas, Klebsiella, Enterobacter and a number of anaerobic organisms, Bacteroides and actinomyces.
8. Liver abscesses are clinically characterised by pain in the right upper quadrant, fever, tender hepatomegaly and sometimes jaundice.
9. Laboratory examination reveals leucocytosis, elevated serum alkaline phosphatase, hypoalbuminaemia and a positive blood culture.

Morphologic Features: Grossly, depending upon the cause of the pyogenic liver abscess, they occur as single or multiple yellow abscesses, 1 cm or more in diameter, in an enlarged liver.

• A single abscess generally has a thick fibrous capsule. The abscesses are particularly common in the right lobe of the liver. Microscopically, typical features of abscess are seen.
• There are multiple small neutrophilic abscesses with areas of extensive necrosis of the affected liver parenchyma. The adjacent viable area shows pus and blood clots in the portal vein, inflammation, congestion and proliferating fibroblasts.
• Direct extension from the liver may lead to subphrenic or pleuro-pulmonary suppuration or peritonitis. There may be small pyaemic abscesses elsewhere such as in the lungs, kidneys, brain and spleen.

Amoebic Liver Abscess

• Amoebic liver abscesses are less common than pyogenic liver abscesses and have many similar features. They are caused by the spread of Entamoeba histolytic from intestinal lesions.
• The trophozoite form of amoebae in the colon invades the colonic mucosa forming flask-shaped ulcers from where they are carried to the liver in the portal venous system.
• Amoebae multiply and block small intrahepatic portal radicles resulting in infarction necrosis of the adjacent liver parenchyma.
• The patients, generally from tropical and subtropical countries, may give a history of amoebic dysentery in the past. Cysts of E.
• histolytic in stools is present in only 15% of patients with hepatic amoebiasis. Intermittent low-grade fever, pain and tenderness in the liver area are common presenting features.
• A positive haemagglutination test is quite sensitive and useful for the diagnosis of amoebic liver abscess.

• Morphologic Features Grossly, amoebic liver abscesses are usually solitary and more often located in the right lobe in the posterosuperior portion.
• An amoebic liver abscess may vary greatly in size but is generally the size of an orange. The centre of the abscess contains a large necrotic area having reddish-brown, thick pus resembling anchovy or chocolate sauce.
• The abscess wall consists of irregular shreds of necrotic liver tissue. Histologically, the necrotic area consists of degenerated liver cells, leucocytes, red blood cells, strands of connective tissue and debris.
• Amoebae are most easily found in the liver tissue at the margin of the abscess. PAS-staining is employed to confirm the trophozoites of E. histolytic.