Histologically, NAFLD resembles alcoholic liver disease, but it occurs in
individuals without significant alcohol consumption. Average alcohol consumption
greater than two drinks per day in men and greater than one drink
per day in women generally is not consistent with a diagnosis of NAFLD. In
addition, the definition of NAFLD excludes patients with a history of exposure
to steatogenic medications such as amiodarone, methotrexate, and
tamoxifen.
NAFLD encompasses a spectrum of abnormal liver histology, ranging
from simple steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis.
In simple steatosis, liver histology reveals macrovesicular steatosis without
ballooning degeneration of hepatocytes or liver fibrosis. NASH, which is a
more advanced form of NAFLD, is histologically characterized by macrovesicular
steatosis, ballooning degeneration of the hepatocytes, and sinusoidal
fibrosis.