Histopathological Diagnosis of Nonalcoholic Steatohepatitis (NASH)

Nonalcoholic steatohepatitis (NASH) is part of a spectrum of conditions collectively referred to as nonalcoholic fatty liver disease (NAFLD). NASH/NAFLD is the most common chronic liver disease. NASH is defined as ≥5% hepatic steatosis along with hepatocellular injury. Histopathological features that indicate hepatocellular injury in NASH include ballooning degeneration, lobular inflammation, and apoptotic bodies. Scoring schemes, such as the NASH Clinical Research Network (CRN), use those histopathological features to grade the severity of the disease and determine a stage based on the amount of fibrosis. Among the NAFLD spectrum, NASH has the highest risk of developing fibrosis and progressing to liver cirrhosis. Therefore, accurate and timely diagnosis is crucial in order to initiate therapy and prevent disease complications as well as liver-related mortality. Although several imaging modalities and laboratory assays have been introduced to diagnose NASH, a liver biopsy remains the gold standard for diagnosing, grading, and staging the disease.