Myeloid metaplasia, perisinusoidal fibrosis, and nodular regenerative hyperplasia of the liver.

We describe two patients with myeloid metaplasia in whom portal hypertension resulted, not from infiltration of the liver sinusoids by myeloid cells, but from perisinusoidal fibrosis and nodular regenerative hyperplasia of the liver. We hypothesize that myeloid metaplasia induced the development of perisinusoidal fibrosis, which resulted in heterogeneous hepatic tissue blood perfusion, with atrophy of the liver cells in the underperfused areas and nodular regenerative hyperplasia in the normally perfused areas.