Nonalcoholic fatty liver disease: what the pathologist can tell the clinician.

Liver biopsy evaluation continues to serve a significant, often primary, role in clinical care, as well as in fundamental aspects of investigation in nonalcoholic fatty liver disease (NAFLD). This is a review of the major features of liver pathology in NAFLD and specifically what role liver biopsy continues to play in both clinical management and scientific investigation. Diagnostic criteria for NAFLD and nonalcoholic steatohepatitis in adults and children are discussed, as are other histologic features that may be encountered. Histologic features for diagnostic classification(s) of NAFLD and semiquantitative methods of assessment are reviewed. The unique patterns of injury and fibrosis that characterize this disease are emphasized, and reasons why histologic scoring and diagnosis are considered as interrelated but separate exercises given. In addition, pros and cons and recognized limitations of liver biopsy in NAFLD are discussed.