HEPATIC ABSCESS

HEPATIC ABSCESS
  • Abscess is characterised by aggregates of inflammatory cells chiefly neutrophils
  • Microscopic clusters of neurtophils in the parenchyma called microabscesses on also occur.
  • Hepatic abscesses arise either directly from the hepatic artery due to systemic bacteraemia or from the biliary tree secondary to partial bile duct obstruction with ascending cholangitis.
  • Abdominal infection may initiate inflammation of portal vein and its radicals (pyelophlebitis) with secondary abscess formation.
Pyogenic Abscess:
  • Sources of infection:
    • Seeding of bacteria from the
      • Biliary tract
      • Portal blood
      • Arterial blood (septicemia)
      • Direct extension from a contiguous infection, subphrenic abscess, perforated cholecystitis
      • Hepatic trauma and cannulation of umbilical vessels in the neonate
  • Organisms causing
    • Common organisms E.coli, klebsiella pneumonia, Enterococcus, Streptococcus  and Pseudomonas species
    • Fungi such as candida and aspergillus can cause
    • Anaerobes in 25% of cases –Microaerophilic streptococci, Bacteroides fragilis, Fusobacterium, Clostridia species, Actinomyces species
    • Other causes are
      • Melioidosis
      • Brucellosis
      • Listeria monocytogenes
      • 1/3rd are polymicrobial.
  • Risk factors:
    • Diabetes mellitus, malignancy, alcohol abuse, cirrhosis, HTN, recent surgery and immunosuppression
    • Mortality ranges from 5-3%
  • Clinical features
    • Males are more affected than females
    • Age-55-60 years.
    • Symptoms include fever, chills, right upper quadrant pain  and elevated alkaline phosphatase
  • Site of Abscess – common in right lobe may be single or multiple.
  • Content – Contain creamy yellow, foul swelling pus that contains necrotic tissue and neutrophils.
  • A fibrous capsule may be present.
  • Microscopy
    • Necrotic parenchyma infiltrated by neutrophils
    • Area of suppurative cholongitis with accumulation of neutophils and fibrin with in duct.
    • Histocytes may also be noted.
  • Laboratory investigations: 
    • Culture of aspirated purulent material.
    • Culture of peripheral blood.
Amoebic abscess:
  • It is caused by Entamoeba histolytica
  • Site – Preferentially in right lobe
  • Contents – Cavity contains classic orange, brown, pasty, blood stained necrotic hepatic lesion (anchovy sauce)
  • This material is ordorless and bacteriologically sterile and contains no neutrophils, unless it is secondary infected.
  • Organism is found most often in periphery of abscess which posses a shaggy necrotic fibrinous zone and a layer of granulation tissue.
  • Trophozoites -10 to 60µm in diametre and contain small single round nucleus with distinctive central karyosome, a thick, beaded nuclear membrane and bubbly cytoplasm often containing phagyposed RBC’s.
  • Macrophages have more bean shaped nucleus, finer chromatin, more delicate nuclear membrane and small nucleoli.