Diffuse fatty infiltration is a common imaging finding due to the abnormal accumulation of lipids within hepatocytes. Baseline US is typically the first imaging modality for the evaluation of hepatic steatosis, but causing a conspicuous increase in liver echogenicity and a marked ultrasound beam attenuation, it really hampers FLL detection and characterization. Moreover, geographic fatty changes of the liver can occur when the fat accumulation ability of hepatocytes or fat deposition becomes heterogeneous throughout the liver and are classified into four subtypes: (a) focal fatty change, (b) multifocal steatosis, (c) lobar or segmental steatosis, and (d) focal fatty sparing in fatty liver [1].

In particular, focal fatty change and focal fatty sparing can show a round, mass-like appearance on imaging, making difficult a correct differential diagnosis with malignant lesions in oncological patients. At this regard, CEUS has been reported to improve the characterization of focal hepatic lesions in patients with fatty liver and in diagnosing both focal fatty infiltration and sparing [2]. But there are different and controversial data in literature about the usefulness of CEUS in the screening and follow-up of oncological patients [3–9]. Anyway, WFUMB-EFSUMB guidelines recommend CEUS in the surveillance of oncological patients (if CEUS has been useful previously), for the evaluation of liver metastases in colorectal cancer after chemotherapy instead of unenhanced US, or for lesion(s) or suspected lesion(s) detected with US in patients with a known history of a malignancy as an alternative to CT or MRI [10–12].