Histopathological Changes of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. Although imaging techniques and serologic testing are important examinations, histology remains the gold standard to establish the diagnosis, to stratify to grade and stage the actual sample. There are two major subtypes of NAFLD, simple steatosis and the progressive form nonalcoholic steatohepatitis (NASH). Simple steatosis is characterized by fat accumulation in hepatocytes. NASH can be diagnosed if, in addition to steatosis, inflammation and hepatocyte damage in the form of ballooning is present in the liver. There may be other histological alterations with variable significance e.g. fibrosis, ductular reaction, granulomas, Mallory-Denk bodies, etc. NASH is a progressive disease, which can end up in cirrhosis. Hepatocellular carcinoma (HCC) is also a well-known complication of NASH. It can develop in cirrhotic and surprisingly in non-cirrhotic stage of NASH. The histological signs of NASH can be substantially different in pediatric patients, than in adults. Several histological scoring systems have been developed for reliable grading and staging of NAFLD. They can be used to follow up the progression of the disease, monitor the efficacy of potential therapies and to compare different studies. Future will decide which one of them proves to be most reliable, and reproducible. Finally, histological diagnosis can be important to distinguish NAFLD from other chronic liver diseases or recognize comorbidities.

Keywords: Ballooning, Cirrhosis, Ductular reaction, Hepatic fibrosis, Hepatocellular carcinoma, Mallory-Denk bodies, Scoring, Steatohepatitis, Steatosis.