Diagnostic approach to needle biopsies of hepatic mass lesions

A practical diagnostic approach to hepatic masses

The differential diagnosis of hepatic mass lesions is broad and arriving at the right diagnosis can be challenging, especially on needle biopsies. The differential diagnosis of liver tumors in children is different from adults and is beyond the scope of this review. In adults, the approach varies depending on the age, gender, and presence of background liver disease. The lesions can be divided broadly into primary and metastatic (secondary), and the primary lesions can be further divided into those of hepatocellular origin and nonhepatocellular origin. The first category consists of benign and malignant lesions arising from hepatocytes, while the second category includes biliary, mesenchymal, hematopoietic, and vascular tumors. Discussion of nonepithelial neoplasms is beyond the scope of this review. The hepatocytic lesions comprise dysplastic nodules, focal nodular hyperplasia, hepatic adenoma, and hepatocellular carcinoma, and the differential diagnosis can be challenging requiring clinicopathological correlation and application of immunohistochemical (IHC) markers. Liver is a common site for metastasis, sometimes presenting with an unknown primary site, and proper workup is the key to arriving at the correct diagnosis. The correct diagnosis in this setting requires a systematic approach with attention to histologic features, imaging findings, clinical presentation, and judicious use of IHC markers. The list of antibodies that can be used for this purpose keeps on growing continually. It is important for pathologists to be up to date with the sensitivity and specificity of these markers and their diagnostic role and clinical implications. The purpose of this review is to outline the differential diagnosis of hepatic masses in adults and discuss an algorithmic approach to make a right diagnosis.

Diagnostic Approach to Hepatic Mass Lesions and Role of Immunohistochemistry

This review provides an overview of various hepatic mass lesions and a practical diagnostic approach, including most recent immunohistochemical stains used in clinical practice. A wide variety of benign and malignant lesions present as hepatic masses, and the differential diagnosis varies. In cirrhotic liver, the commonest malignant tumor is hepatocellular carcinoma (HCC), which needs to be differentiated from macroregenerative nodules, dysplastic nodules, and other tumors. The differential diagnosis of lesions in noncirrhotic liver in younger patients includes hepatic adenoma (HA), focal nodular hyperplasia (FNH), HCC, and other primary hepatic neoplasms and metastases. In older populations, metastases remain the most common mass lesions.

Molecular pathology of hepatic neoplasms: classification and clinical significance

Recent technological advances have enabled investigators to characterize the molecular genetics and genomics of hepatic neoplasia in remarkable detail. From these studies, an increasing number of molecular markers are being identified that correlate with clinically important tumor phenotypes. This paper discusses current knowledge relevant to the molecular classification of epithelial primary hepatic tumors that arise in adults, including focal nodular hyperplasia (FNH), hepatocellular adenoma (HCA), hepatocellular carcinoma (HCC), cholangiocarcinoma (CC), and combined HCC-CC. Genetic analysis has defined molecular subtypes of HCA that are clinicopathologically distinct and can be distinguished through immunohistochemistry. Gene expression studies have identified molecular signatures of progression from dysplastic nodules (DNs) to early HCC in cirrhosis. Analyses of the mutational spectra, chromosomal aberrations and instability, transcriptomics, and microRNA profiles of HCC have revealed the existence of biologically distinct subtypes of this common malignancy, with prognostic implications. Molecular characterization of biliary and hepatic progenitor cell phenotypes in liver cancer has shed new light on the histogenesis of these tumors and has focused attention on novel therapeutic targets. In coming years, the molecular classification of hepatic neoplasms will be increasingly valuable for guiding patient care, as targeted therapies for liver cancer are developed and brought into clinical practice.