Nonalcoholic steatohepatitis: A proposal for grading and staging the histological lesions

OBJECTIVE: Steatohepatitis is a morphological pattern of liver injury that may be seen in alcoholic or nonalcoholic liver disease. This pattern may oc cur with obesity, diabetes, the use of certain drugs, or the cause may be i diopathic. The well-recognized histopathological features of nonalcoholic s teatohepatitis (NASH) include hepatocellular steatosis and ballooning, mixe d acute and chronic lobular inflammation, and zone 3 perisinusoidal fibrosi s. Currently, there are no systems for grading necroinflammatory activity o r for staging fibrosis as-exist for various other forms of chronic liver di sease. The purpose of this study was to develop such a grading and:staging system and was based on review of liver biopsies-from 51 patients with nona lcoholic steatohepatitis from Saint Louis University Health Sciences Center . METHODS: For determination of grade, 10 histological variables of activity were initially analyzed; an overall impression of mild, moderate, and sever e was made and the variables considered to be most significant were used to develop the necroinflammatory grade. RESULTS: The histological lesions considered to be significant were: steato sis, ballooning, and intra-acinar and portal inflammation. A staging score was developed to reflect both location and extent of fibrosis. The fibrosis score was derived from the extent of zone 3 perisinusoidal fibrosis with p ossible additional portal/periportal fibrosis and architectural remodeling. Fibrosis stages are as follows: Stage 1, zone 3 perisinusoidal fibrosis; S tage 2, as above with portal fibrosis; Stage 3, as above with bridging fibr osis; and Stage 4, cirrhosis. CONCLUSION: We propose a grading and staging system that reflects the uniqu e histological features of nonalcoholic steatohepatitis.: (Am J Gastroenter ol 1999;94:2467-2474. (C) 1999 by Am. Coll. of Gastroenterology).