Nodular regenerative hyperplasia of the liver. Report of two cases associated with autoimmune disease.

Nodular regenerative hyperplasia of the liver (N.R.H.) is an uncommon clinicopathological entity characterized by diffuse regenerative hepatocytic nodules without fibrosis. Grossly the lesion is often mistaken for cirrhosis. The etiology and pathogenesis are unknown. We report two new cases of N.R.H. diagnosed by liver biopsy. Peritoneoscopically the liver showed a nodular surface resembling micronodular cirrhosis. Both patients showed some clinical and immunological features of autoimmune disease, and in both cases N.R.H. was associated with chronic active hepatitis. We discuss the pathological differential diagnosis of N.R.H., its relation to other associated diseases and review the hypotheses for the pathogenesis of this condition.