Amoebic Liver Necrosis in Contrast-Enhanced Ultrasound
[November 2023]

A 44-year-old patient with fever, weakness, bloody stools, and elevated infectious markers presented at the emergency department. The patient had multiple recent visits to India. In the stool analysis using multiplex PCR, Entamoeba histolytica was detected. Computed tomography identified several partially septated lesions suggestive of amoebic liver necrosis.

B-mode ultrasound (B-US) revealed several anechoic, partially septated lesions in the liver. On contrast-enhanced ultrasound (CEUS), the lesions consistently displayed a predominant absence of enhancement throughout the examination, with no rim enhancement in the arterial phase or perilesional wash-out in the portal venous phase. The septa showed contrast enhancement (Fig 1).

Amoebic necrosis of the liver.

Infectious liver lesions display different CEUS patterns dependent on the pathogen involved. Unlike pyogenic abscesses (Fig 2), amoebic liver lesions—often termed sterile abscesses—lack a defined wall, show no rim enhancement in the arterial phase, and exhibit no peripheral wash-out in the portal venous phase.

-An infectious amoebic lesion of the liver, if not secondarily infected, constitutes sterile necrosis. Enhancement of the septa may be observed.

-Unlike pyogenic abscesses (Fig 2), these lesions do not show pronounced rim enhancement or wash-out phenomena on CEUS, which would indicate inflammatory obstruction of the portal vein branches in pyogenic abscesses.

- The term "liver abscess" refers to a collection of pus (neutrophil granulocytes) in the liver and should not be applied to infectious amoebic lesions. Instead, "amoebic necrosis" is the preferred nomenclature. A therapeutic evacuation of the lesion is not necessary.

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