Update on Fatty Liver Disease and SteatohepatitisAly, Fatima Zahra MD, PhD; Kleiner, David E. MD, PhDAdvances in Anatomic Pathology: July 2011 - Volume 18 - Issue 4 - p 294–300 doi: 10.1097/PAP.0b013e318220f59b Review Articles Abstract Author Information Non-alcoholic fatty liver disease (NAFLD) is a broad term that includes liver diseases characterized by abnormal hepatocellular accumulations of lipid that cannot be related to alcohol abuse. It may be found in both adults and children, particularly those who are obese or have insulin resistance. Steatohepatitis is a specific pattern of injury within the spectrum of NAFLD and this pattern is associated with fibrotic progression and cirrhosis. In addition to steatohepatitis, a distinct form of fibrotic fatty liver disease exists in children. There have been a number of recent advances in the characterization of histologic changes in NAFLD. In light of these recent reports, this study will: (1) review the histologic features of steatosis and nonalcoholic steatohepatitis in adults; (2) review the variation of histologic patterns of pediatric fatty liver disease; and (3) discuss the validity and use of the nonalcoholic fatty liver disease Activity Score. Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD Supported by the Intramural Research Program of the NIH, National Cancer Institute. The authors declare no conflict of interest. Reprints: David E. Kleiner, MD, PhD, Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (e-mail: firstname.lastname@example.org). © 2011 Lippincott Williams & Wilkins, Inc.