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.
