Idiopathic myelofibrosis with extramedullary hematopoiesis in the kidneys

Extramedullary hematopoiesis is a common finding in idiopathic myelofibrosi s and is usually found in liver and spleen. We report on a patient with bio psy-proven myeloid metaplasia and fibrosis of the renal parenchyma as a rar e cause of chronic renal failure. The renal biopsy specimen showed numerous infiltrates of hematopoietic cells expressing growth factors like M-CSF, G M-CSF, IL-1 beta and PDGF while TGF-beta was not elevated. These findings s uggest that hematopoietic growth factors play a key role in the pathogenesi s of this condition causing proliferating fibrosis and enlargement of the k idneys.