Pitfalls in the diagnosis of hepatic cysts by computed tomography.

Seven patients with computed tomographic (CT) evidence of cystic hepatic lesions are presented. In these cases, CT could not reliably distinguish benign hepatic cysts from other intrahepatic and extrahepatic cystic lesions. The attenuation coefficients of simple cysts and inflammatory or neoplastic lesions were similar, and smooth margins occurred in all three of these conditions. It was not possible to visualize and differentiate lesion walls from the surrounding normal hepatic parenchyma in some cases. It is concluded that the specificity of CT in the differentiation of benign cysts and other lesions is lower in the liver than it is in other areas, such as the kidney, and that in cases of diagnostic uncertainty, biopsy should be performed.