Nonalcoholic fatty liver disease.

The definition of nonalcoholic fatty liver disease has evolved in recent years. Today, it is considered a nonspecific term encompassing several clinicopathologic entities (steatosis alone, steatonecrosis, steatohepatitis and histologic alcoholic-like hepatitis) that are similar to alcoholic liver disease. Studies of nonalcoholic fatty liver disease have come to conflicting conclusions about the course of the disease. It can be argued that the disparate results are largely the result of nonuniform definitions. When histologic features such as hepatocyte ballooning, necrosis, and Mallory hyaline are seen, nonalcoholic fatty liver disease has been shown to be associated with an aggressive outcome. Steatosis alone, in contrast, appears to be benign. The current understanding of nonalcoholic fatty liver disease, the limited treatments available, and two theories of the pathogenesis of the disease are also reviewed here.