Approaching focal liver lesions.

Focal liver lesions are defined as solid or liquid-containing masses foreign to the normal anatomy of the liver that may be told apart from the latter organ using imaging techniques. Their nature is widely varying, and may range from benign lesions with an indolent clinical course to aggressive malignant tumors (Table I). They are common findings as a result of the ever increasing use of imaging techniques in patients with nonspecific abdominal complaints (1). The etiopathogenic diagnosis of focal liver lesions is based on clinical findings, laboratory data, imaging techniques, and frequently histology (1,2). Beforehand, incidental lesions in asymptomatic patients with no history of neoplasms or liver disease are usually benign, and cysts, hemangiomas and focal nodular hyperplasia (FNH) are most prevalent in our setting (3). In contrast, liver lesions in cirrhotic patients demand that hepatocellular carcinoma (HCC) be ruled out. Initial assessment is relevant to exclude factors predisposing to selected tumors. Thus, a history of oral contraceptive use in a young woman suggests hepatocellular adenoma, cirrhosis is a preneoplastic condition for hepatocellular carcinoma, and sclerosing cholangitis predisposes to cholangiocarcinoma. Serologic tests for hepatitis viruses, Echinococcus and Entamoeba may suggest a diagnosis, as a number of tumor markers also do. However, a definite diagnosis is established using two essential tests: imaging techniques and a cytohistologic study. Radiographic features provide a hint of a lesion’s solid (benign or malignant tumors) or liquid (cysts, abscesses, etc.) contents. Solid tumor vascularization provides guidance on their etiology (3). Characteristically, tumors with arterial hypervascularization may be benign –adenomas or FNH– or malignant, such as hepatocellular carcinoma, and metastases from neuroendocrine tumors or hypernephroma. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) with vascular (gadolinium) or ferric (ferumoxides) contrast media have taken over radionuclide tests, and often allow getting around histology. Approaching focal liver lesions