Focal fatty liver sparing lesion presenting as a "pseudotumour": case report.

We are reporting our experience of a case of "focal fatty liver sparing lesion" in a 24-year-old patient, without any evident predisposing factors for fatty infiltration of the liver. Fatty liver infiltration was sparing the posterior part of liver segment VI, defining an area which was mimicking a lesion on US and CT. Fatty liver infiltration is usually diffuse but may be patchy or localized. Occasionally, focal areas of normal parenchyma in an otherwise diffuse fatty liver may simulate mass lesions. Typically, these "pseudolesions" appear as echo-poor areas against a background of bright echoes due to fatty infiltration and may pose a difficult diagnostic problem. We present this case and discuss the investigation process in order to differentiate this lesion from a hepatic tumor.