Nonalcoholic Fatty Liver Disease

Pouneh S. Mofrad, MD, Arun J. Sanyal, MD


April 16, 2003

In This Article


Fatty disorders of the liver are defined by 2 major histologic patterns of steatosis within hepatocytes. Microvesicular steatosis is characterized by the presence of numerous small vesicles of fat that do not displace the nucleus (Figures 1, 2). Macrovesicular steatosis is characterized by engorgement of the hepatocyte by a large fat globule that displaces the nucleus.

Figure 1.

Two patterns of hepatic steatosis are recognized: (1) microvesicular steatosis: the cytoplasm is replaced by bubbles of fat that do not displace the nucleus; and (2) macrovesicular steatosis: the cytoplasm is replaced by a large bubble of fat that displaces the nucleus to the edge of the cell.
From Sanyal AJ. Nonalcoholic steatohepatitis. Clinical Perspectives in Gastroenterology. 2000;129(May/June). Copyright 2000; republished with permission from Elsevier.

Figure 2.

Steatohepatitis is shown here. The histologic findings shown include macrovesicular steatosis, cytologic ballooning, Mallory bodies, and scattered lobular inflammation.

There are 2 principal lesions of fatty liver disease: a pure fatty liver alone and steatohepatitis ( Table 1 ). When fatty liver occurs in an individual who does not consume alcohol in quantities considered to be harmful to the liver, it is referred to as nonalcoholic fatty liver disease (NAFLD).[1] This condition was originally identified in morbidly obese individuals, especially after weight loss surgery, and in women who were diabetic.[2,3] It is now known that NAFLD occurs in men as well as in individuals who are not diabetic, and it is increasingly being recognized as a major cause of liver disease.