Development of pyogenic liver abscess is the result of infection through the following routes like portal vein (also from pylephlebitis of portal vein), hepatic arteries as metastatic abscesses, direct spread from nearby infection, trauma and retroperitoneal extension from appendix.^[1][2][3][4]Ascending biliary infection is the most common source of pyogenic liver abscess.

• Development of pyogenic liver abscess is the result of extension of infection through the following:^[1][2][3][4]

• Portal vein (also from pylephlebitis of portal vein)
• Hepatic arteries as metastatic abscesses
• Direct spread from nearby infection
• Trauma
• Retroperitoneal extension from appendix (suppurative appendicitis most frequent source of infection)

• Ascending biliary infection is the most common source of pyogenic liver abscess.
• Right lobe of liver is most commonly involved due to its greater blood supply than caudate and left lobes.
• Bacteria involved in pyogenic liver abscess include:

• In healthy patients the reticuloendothelial cells (kupffer cells) of liver control the transient portal bacteremia but in elderly and immunocompromised the bacteria can overwhelm the kupffer cells and lead to an abscess.^[5]

• Single or multiple cavities, filled with fowl smelling, creamy yellow necrotic material, usually in right lobe of liver.
• The abscess may have fibrous capsule which is a centimeter or more thick and gradually merges into the liver parenchyma.

• Multiple neutrophilic abscesses with areas of necrosis are seen in the liver parencyma.^[6][7]
• Suppuration, liquefaction with presence of fibrino-purulent debris, and fibrosis are seen depending on stage.
• The edges of the cavities are composed of a chronic inflammatory infiltrate consisting of lymphocytes, epithelioid macrophages, eosinophils, and neutrophils.
• Adjacent hepatocytes appear reactive.