Pathological Findings of NASH and NAFLD: for Guidebook of NASH and NAFLD, 2015: The Japan Society of Hepatology.

Nonalcoholic fatty liver disease (NAFLD) is an increasingly common chronic liver disease worldwide. NAFLD comprises a variety of clinical and histopathological changes that can be broadly divided into nonalcoholic fatty liver (NAFL, simple steatosis) and nonalcoholic steatohepatitis (NASH). The differential diagnosis between NAFL and NASH is important because NASH is a more advanced form. This diagnosis therefore determines the prognosis and therapeutic management. At present the interpretation of NASH is made based on the histopathological features of steatohepatitis, i.e. 'steatosis', 'lobular inflammation', hepatocyte 'ballooning, 'Mallory-Denk bodies' and 'fibrosis'. Here, we summarize the pathological findings guidelines for NASH as it was already published in 2015 in Japanese in the clinical guidebook organized by the Japan Society of Hepatology.