Nodular regenerative hyperplasia (NRH) is a common form of non-cirrhotic portal hypertension. It should be considered whenever stigmata of portal hypertension is present in a patient without liver fibrosis. Synthetic function is usually preserved.
Causes of NRH include medications (azathioprine, chemotherapy), collagen vascular disease (SLE), HIV, PBC and idiopathic.
A distinguishing feature of NRH is the absence of fibrosis between the hyperplastic nodules, although fibrosis is occasionally seen in the periportal or perisinusoidal areas. In the specimen above, notice the ‘N,’ representing thickened liver cell plates, alternating with zones in which cell plates are compressed (arrows). These nodules are clustered around the portal triad. In many cases, the central veins are compressed by the hypertrophied hepatocytes or they show evidence of veno-occlusive changes. Inflammatory features are minimal or absent.