[Focal fatty liver. A dilemma of differential diagnosis in ultrasonography and CT]

Based on four cases and relevant background literature we partly want to draw attention to the occurrence of focal fatty liver (FFL) and its manifold appearances in connection with ultrasonography (US) and computed tomography (CT), and partly to point out possible pitfalls in US-diagnosis of the liver in cases of extensive fatty liver, where the residual foci of normal liver may incorrectly be interpreted as abnormal lesions. US and CT examination of FFL may cause differential diagnostic problems with risk of misinterpretation and erroneous diagnosis, especially if the phenomenon is unknown. In cases of doubt in US examination, where the uncharacteristic findings together with patient information indicate further examinations, additional CT is first of all recommended. If this still brings no clarity to the diagnosis, the clinical condition in every case will prescribe whether to undertake additional CT after a few weeks or immediately carry out US/CT guided liver biopsy. Current as well as formerly presented research shows that FFL is mainly located in the right hepatic lobe, and possible reasons for that are discussed.