Clinicopathological features of non-alcoholic fatty liver disease

Non‐alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease worldwide and its incidence is increasing concomitantly with the increase in the prevalence of metabolic syndrome. Fatty liver encompasses a broad pathological spectrum of disease, from relatively benign accumulation of fat (simple steatosis) to progressive non‐alcoholic steatohepatitis (NASH), which is associated with necroinflammation and fibrosis. Approximately 20–30% of the Japanese population is estimated to have NAFLD, 10% of which is suggested to have NASH. The most worrisome feature of NASH is the potential progression to cirrhosis, hepatocellular carcinoma (HCC), and finally, mortality. Several factors, such as insulin resistance, adipokines, endotoxins and oxidative stress, are involved in the pathogenesis of NASH. However, the precise etiological mechanism of NAFLD/NASH has yet to be elucidated. This article reviews the clinical background, pathogenesis, new diagnostic approaches and future directions regarding NAFLD/NASH.