Spinal cord compression by extramedullary haematopoiesis in myelofibrosis.

A 50-year-old man with a 20-year history of myelofibrosis developed mild impairment of dorsal column sensation and ataxia of gait. A myelogram and subsequent peroperative biopsy demonstrated spinal cord compression due to extramedullary haematopoiesis. There was an excellent clinical response to surgery and radiotherapy. The characteristic clinical features and the pathogenesis of this unusual complication of myelofibrosis and extramedullary haematopoiesis are discussed.