CT of amebic liver abscess.

CT findings in 23 patients with amebic liver abscess were analyzed retrospectively. A solitary abscess was present in 17 patients. Five patients had two to five lesions. One patient, a male homosexual, had 15 abscesses. Of the 46 abscesses, 74% occurred in the right lobe. The lesions were generally round or oval. One-half of the abscesses were 2-6 cm in diameter; 11% measured 13-16 cm. An enhancing wall was present in most cases. An incomplete rim of edema was seen in eight abscesses. The margin of the abscess was smooth in 63% and nodular in 37%. Internal septations were noted in 30%. Four patients had focal intrahepatic biliary dilatation peripheral to an abscess. One patient had intraabscess hemorrhage. Extrahepatic abnormalities were present in 18 patients; right pleural effusion (nine), perihepatic fluid collection (five), gastric or colonic involvement (eight), and retroperitoneal extension (one). Gas within an abscess was due to hepatobronchial fistula in one patient and hepatocolic fistula in another. Amebic abscess should be included in the differential diagnosis when CT shows one or more cystic or complex masses in the liver, especially when there is evidence of extrahepatic extension.