Focal hepatic fatty infiltration as a cause of pseudotumors: ultrasonographic patterns and clinical differentiation.

Focal hepatic fatty infiltration may be mistaken for hepatic neoplasm on ultrasonography. A sonographic feature mimicking "space occupying lesions" was identified in 41 cases with focal fatty liver, which led to the recognition of four sonographic patterns: (1) Ten patients in whom the livers were characterized by irregular configurations of hyperechoic and hypoechoic areas. Although confusing to inexperienced sonographers, all of them were properly interpreted by experienced sonographers. (2) One patient in whom the hepatic sonography revealed a hyperechoic nodule, but which was correctly diagnosed by computed tomography (CT) scan. (3) Six patients in whom the livers were characterized by multiple confluent hyperechoic lesions, which were all misinterpreted by sonographers and misinterpreted following CT scans in 4 cases and angiography in 3 cases. (4) Twenty-four patients in whom the livers revealed focal spared areas, which was misdiagnosed by sonographers in 14 cases, but correctly diagnosed by CT scan in all 24 cases.