Amoebic liver abscess

Amoebic liver abscess
Other names: Amoebic hepatic abscess,Hepatic amebiasis[1]
Top: Gross pathology of liver containing amoebic abscess Bottom:Entamoeba histolytica trophozoite
Specialty	Infectious disease
Symptoms	Fever, right upper quadrant abdominal pain, and tenderness[2]
Causes	Entamoeba histolytica infection[2]
Risk factors	Alcoholism, immunocompromised[2]
Diagnostic method	Ultrasound, CT[2]
Differential diagnosis	Candida[2] Bacterial liver abscess Echinococcus Granulosus
Treatment	Metronidazole[2]

Amoebic liver abscess is a type of liver abscess caused by amebiasis. It is the involvement of liver tissue by trophozoites of the organism Entamoeba histolytica and of its abscess due to necrosis.^[2]

As to treatment we find first-line anti parasitic agents metronidazole or tinidazole are used.Amoebic liver abscess common in tropical regions with poor sanitation: Africa, India, Southeast Asia, and Latin America.^[3][4][2]

Signs and symptoms

Approximately 90% of patients with E histolytica are asymptomatic.^[5] The two most common manifestations of E histolytica include colitis (bloody stool with mucus, abdominal pain, and/or diarrhea), and discovery of a liver abscess on imaging.^[5]Liver abscess' commonly present as right upper quadrant abdominal pain and fever, with worsening features associated with abscess rupture.^[5] Some further the symptoms are:^[2][3]

• Pain right hypochondrium referred to the right shoulder
• Pyrexia
• Profuse sweating and rigors
• Loss of weight
• Jaundice
• Tenderness and rigidity in right hypochondrium
• Intercostal tenderness
• Cough

Complications

As to the possible complications of Amoebic liver abscess we find the following:^[2]

• Rupture into the chest, or pericardium
• Inferior vena cava thrombosis
• Hepatic vein thrombosis

Cause

As to Amebic liver abscess it is caused by the parasite Entamoeba histolytica, which leads to condition called amebiasis or amebic dysentery^[3]

Risk factors

In terms of the risk factors for Amebic liver abscess we find:^[3]

• Alcoholism
• Immunosuppression
• Malnutrition
• Steroid use

Mechanism

As to the pathogenesis of Amoebic liver abscess we find that trophozoites adhere to colonic epithelial cells using Gal/GalNAc lectin.They release cysteine proteinases that degrade extracellular matrix proteins, allowing invasion into submucosal tissues.From the colon, trophozoites enter mesenteric venules, then the portal circulation, reaching the liver.Inside liver, trophozoites induce apoptosis of hepatocytes, leading to necrosis.Most commonly affects the right lobe of the liver due to its vascular supply^[6][7][8][2]

Diagnosis

Diagnosis is primarily made by identifying stool ova and parasites on stool antigen testing in the presence of colitis, or E histolytica serology.^[5][2][3]

• Blood ceruloplasmin
• CT scan
• Stools examination (trophozoites)
• Radiography
• Aspiration exploratory
• Medical ultrasonography
• Sigmoidoscopy
• Liver function tests

• 
  a) Amoebic liver abscess showing the elevation of the right hemi-diaphragm b)single large amoebic abscess and c) three amoebic hepatic abscesses. d) Contrasted computed tomography (CT) scan of a single abscess and e) three clear amoebic liver abscesses
• 
  Magnetic resonance cholangiopancreatography (MRC) image showing a voluminous and heterogeneous collection in the left liver lobe (amoebic abscess)

Differential Diagnosis

The DDx of Amoebic liver abscess is as follows:^[2]

• Candida
• Bacterial liver abscess
• Echinococcus Granulosus
• Salmonella Typhi

Treatment

As to the management of Amoebic liver abscrss is based on Metronidazole at a dose of 500 to 750 mg orally 3 times/day; treatment should be followed by Paromomycin 500 mg 3 times/day (7 days).Due to the side effect of diarrhea Metronidazole and Paromomycin should not be given simultaneously.^[2][3]

Prognosis

In terms of the prognosis of ALA we find that uncomplicated amebic liver abscesses have a good outlook. However, if an abscess breaks into the peritoneum, the mortality rate(after surgery) can be 20 to 50 percent^[2]

Epidemiology

ALA accounts for up to 67 percent of liver abscess cases in endemic regions.It is endemic in tropical and subtropical regions, especially in parts of Asia, Africa, Central and South America.^[3][4]

Male predominance is high, with up to 86 percent of cases occurring in men, around 40 years of age^[4]

History

In terms of history we find that William Osler is credited with describing the first case of amoebic liver abscess in the United States at the end of the 19th century. Additionally, James Annesley reported the association between dysentery and amebic liver abscess in 1828.^[9]

Research

Due to the difficulty of exploring host and amebic factors involved in the pathogenesis of amebic liver abscess in humans, most studies have been conducted with animal models.^[10]

Histopathological findings revealed that the chronic phase of amebic liver abscess in humans corresponds to lytic or liquefactive necrosis, whereas in rodent models there is granulomatous inflammation. However, the use of animal models has provided important information on molecules and mechanisms of the host/parasite interaction in amebic liver abscess.^[10]

See also

• Pyogenic liver abscess

References

External links