Histological Assessment of NAFLD.

Nonalcoholic fatty liver disease (NAFLD) covers a spectrum of histological lesions ranging from steatosis to a complex pattern with hepatocyte injury and inflammation in an appropriate clinical context. The disease has been artificially dichotomized into NAFL (steatosis) and NASH (steatosis with hepatocellular injury and inflammation), but it is increasingly clear that intermediate patterns may exist. More than NASH, the stage of fibrosis was shown to govern prognosis, and for such evaluation, a liver biopsy of adequate size and width is needed. Like for any other chronic liver diseases, semi-quantitative histologic scores have been proposed. They are not useful in clinical practice but concur to categorize homogeneous group of patients according to their histology. Pediatric NAFLD is a growing concern. While a subgroup of children may harbor different but characteristic histological patterns, most of them display a mixed pattern or features similar to the adults. Today, liver histology is the mainstay for clinical trials. Biopsy is used both for enrollment and for assessing benefit of clinical trials. End points such as reversion of NASH or regression of fibrosis are acceptable but require a clear histological definition.