[Histopathological diagnosis and differential diagnosis of nonalcoholic fatty liver disease]

Fatty liver disease is a rising problem worldwide, particularly due to metabolic syndrome. The current prevalence is 20-30%, but a further increase is expected whereby children will also be increasingly affected. The presence of fat in hepatocytes is known as steatosis or, in the case of nonalcoholic origin, nonalcoholic fatty liver (NAFL). It is basically reversible, but can progress to steatohepatitis (NASH) as an active and progressive form of fatty liver disease due to continuous cell damage. This leads to progressive liver fibrosis up to end-stage liver cirrhosis. The gold standard of diagnosis is liver biopsy, in which obesity, inflammation, and hepatocellular damage (hepatocellular ballooning) are assessed for the distinction between NAFL and NASH. The extent of fibrosis indicates the progress of the disease. Childhood and adult fatty liver diseases differ morphologically, particularly in the location and amount of fat, inflammation, and fibrosis. Alcoholic and nonalcoholic fatty liver disease/steatohepatitis cannot be reliably differentiated by histology. Clinical parameters must also be taken into consideration for the differential diagnosis of other diseases associated with fatty liver. The main therapeutic goal is to reduce insulin resistance, which can be achieved through weight loss and lifestyle changes. Recently, however, drug therapies have also become available as a promising therapeutic option.