Amoebic hepatic abscess

Sporadic
hepatogastric fistula - A rare complication of liver abscess - A case report. Axial Abdomen CECT - Abscess (black arrow) with air foci ( blue arrow) in left hepatic lobe. Bilateral minimal pleural effusion.
www.eurorad.org • CC by-nc-sa-4.0
Sporadic
hepatogastric fistula - A rare complication of liver abscess - A case report. Axial Abdomen CECT - Demonstrates communication (orange arrow) between the abscess cavity in left hepatic lobe and stomach through breach in the lesser curvature.
www.eurorad.org • CC by-nc-sa-4.0
Sporadic
hepatogastric fistula - A rare complication of liver abscess - A case report. Coronal Abdomen CECT - Demonstrates communication (orange arrow) between the abscess cavity in left hepatic lobe and stomach through breach in the lesser curvature.
www.eurorad.org • CC by-nc-sa-4.0
Development
of amoebic liver abscess in early pregnancy years after initial amoebic exposure: a case report. a 2D abdominal ultrasound performed on the day of presentation shows a hypoechogenic, inhomogenous and approximately 4 × 5 cm large lesion in hepatic segment V. b Contrast-enhanced ultrasound of the liver reveals peripheral hypervascularization of the lesion in segment V without central uptake of contrast, a finding consistent with liver abscess
bmcgastroenterol.biomedcentral.com • CC-by-4.0
Development
of amoebic liver abscess in early pregnancy years after initial amoebic exposure: a case report. a Coronary MRI image of the liver without contrast reveals a T1-hypointense hepatic lesion, adjacent to the gall blader (indicated with *). b Axial MRI sequences showing diffusion restriction to the center of the lesion (* = gall bladder). c 2D sonography after successful transhepatic puncture and drainage. The green dots depict the direction of puncture, the hyperechogenic reflexes within the lesion are caused by the drainage
bmcgastroenterol.biomedcentral.com • CC-by-4.0
Amoebic liver
abscess – a cause of acute respiratory distress in an infant: a case report. Chest X-ray showing right-sided massive pleural effusion. (A) Before drainage. (B) After drainage.
jmedicalcasereports.biomedcentral.com • CC-by-2.0
Amoebic liver
abscess – a cause of acute respiratory distress in an infant: a case report. Computed tomography scan of the liver showing the liver abscess.
jmedicalcasereports.biomedcentral.com • CC-by-2.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Amoebic hepatic abscesses are a form of hepatic abscess resulting from Entamoeba histolytica infection.

Epidemiology

Hepatic abscess is the most common extraintestinal form of E. histolytica infection .

Although the causative pathogen is found worldwide, it is endemic to the Middle East and Eastern Asia and travel history should always be sought in suspected cases.

It has a strong male predominance, about 10:1 .

Clinical presentation

Patients may experience general malaise, presenting with frank sepsis and right upper quadrant pain.

Etiology of the abscess can be inferred based on :

  • identification of E. histolytica specific antigen or DNA in stool samples
  • antiamoebic antibodies in blood serum 

Radiographic features

They can sometimes be difficult to differentiate from other liver abscesses. They tend to be round or oval and be variable in size although most are around 2-6 cm in diameter. An enhancing wall is present in most cases.

Other described features include:

  • an incomplete rim of edema
  • the margin of the abscess tends to be smooth in around 60% of cases and nodular in around 40%
  • internal septations: present in around 30% of cases
  • focal intrahepatic biliary dilatation peripheral to an abscess is an uncommon manifestation

Extrahepatic pathology can be present in a considerable amount of patients, including:

  • pleural effusion
  • perihepatic fluid collection
  • gastric or colonic involvement
  • retroperitoneal extension
Ultrasound

May appear as a hypoechoic lesion with low-level internal echoes and absence of significant wall echoes.

CT

Usually appear as rounded, well-defined lesions with attenuation values that indicate the presence of complex fluid (e.g. 10–20 HU). An enhancing wall and a peripheral zone of edema may be seen with wall thickness around 3-15 mm. The central abscess cavity can show septations and/or fluid-debris levels.

Gas can be present within an abscess if there is a complicating hepatobronchial fistula or a hepatocolic fistula.

MRI

Described signal characteristics include:

  • T1: generally homogeneous low signal intensity (signal homogeneity within the abscess can be present more often on T1- than on T2-weighted images )
  • T2: generally homogeneous high signal intensity; perilesional edema may be seen in half of the cases

Treatment and prognosis

Management centers on initiating anti-parasitic agents, most commonly metronidazole which also treats amoebic dysentery .

Traditionally, amoebic abscesses are treated with medical therapy as the first line as opposed to percutaneous or surgical drainage, which is the first line of treatment in pyogenic liver abscesses.

In practice, percutaneous drainage may frequently be required, particularly in:

  • uncertain diagnosis
  • larger abscesses which are at risk of spontaneous rupture into the peritoneal, pleural, or pericardial spaces
  • failed response to metronidazole therapy - proposed as persistent symptoms after 4 days

Practical points

  • amoebic abscesses may take up to 2 years to complete resolve on imaging; consequently, persistent imaging findings alone should not guide further management 
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