Amoebic hepatic abscess

Case contributed by Travis Fahrenhorst-Jones

Presentation

Three days of pyrexia with associated right upper quadrant pain. Murphy negative.

Patient Data

Age: 35 years
Gender: Male
  • large mass lesion in right lobe of the liver demonstrates a heterogeneous peripheral enhancement pattern in keeping with a large liver abscess
  • thick-walled appearance to the cecal pole with multiple small lymph nodes of the cecal mesentery and a dilated appearance to the appendix
  • several small prominent loops of small bowel

Ultrasound guided drainage

  • abscess accessed with a 20cm 18-gauge Chiba needle followed by a 10Fr pigtail catheter insertion
  • 80mls of heavily purulent material aspirated followed by 300ml saline lavage until the return of relatively clear fluid

E. histolytica PCR of aspirated material returned positive. Stool PCR also returned positive for E. histolytica infection. The patient was subsequently discharged on antibiotics.

Follow up US 4 weeks later

  • hypoechoic lesion in segment 8 representing subcapsular liver abscess
  • stable if not improved in size compared to prior imaging

Case Discussion

E. histolytica infection occurs due to ingestion of cysts in contaminated food or water. The parasite is present widely in the tropics and subtropics causing up to 40 million infections on an annual basis 1. As in this case, the patient was a migrant from a developing tropical country. 

When cysts reach the small intestine, excystation occurs resulting in trophozoites that penetrate the mucosa of the bowel 1 . Access to the portal venous system via this route may result in infection of the liver, brain, lungs, and pericardium. Abscess of the liver is the most common site of extraintestinal infection but occurs in less than 1% of infections 1

E. histolytica disease results in up to 100,000 deaths annually and is the third leading parasitic cause of death in developing countries 2. It is important to note, however, that clinical disease only occurs in a minority of infections and amoebic liver abscesses can develop years later following initial infection as was likely the case in this patient 2

Complete resolution of E. histolytica liver abscesses on imaging may take up to two years, and therefore imaging features alone should not dictate management 3.

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