Ultrasound patterns and frequency of focal liver lesions after successful treatment of amoebic liver abscess.

Objective: To evaluate the frequency and morphology of residual liver lesions in patients successfully treated for amoebic liver abscess.

Methods: Retrospective ultrasound-based study of 240 adult males from an amoebiasis-endemic area in Vietnam with a documented clinical history of amoebic liver abscess. Subjects were re-examined by hepatic ultrasound 1-13 years after abscess treatment.

Results: In 17 subjects (7.1%) focal hypo- or isoechoic areas were identified within the liver with a diameter of 8-48 mm surrounded by a hyperechoic wall. These lesions were associated with positive amoeba serology, were located at the site of the previous abscess and their sonographic appearances corresponded to post-amoebic liver abscess residues. Residues were found in all groups of patients irrespectively of the time-span since the abscess was treated. However, lesions older than 7 years showed some degree of calcification. Otherwise, lesions were apparently inactive, as patients had no clinical symptoms or signs of inflammation and follow-up after one year revealed no changes in size or pattern.

Conclusion: The vast majority of amoebic liver abscesses resolve to a sonographically normal parenchymal pattern. However, in a small proportion of cases characteristic residues remain. These residues do not require further treatment or diagnostic intervention and should be considered in the differential diagnosis of space-occupying liver lesions, in particular in patients from amoebiasis-endemic areas.