A pleural effusion caused by fibrous hematopoietic tumor successfully treated with prednisolone in a patient with agnogenic myeloid metaplasia with myelofibrosis.

A 46-year-old woman suffering from agnogenic myeloid metaplasia (AMM) since 1994 was being followed as an outpatient. In November 1999, she exhibited respiratory failure caused by massive pulmonary effusion, which was speculated to have been produced by chest tumors. A biopsy specimen revealed findings compatible with fibrous hematopoietic tumor (FHT): prominent fibroblasts and fibrosis with scantv megakaryocytes. Serum concentrations of transforming growth factor (TGF)-beta and platelet-derived growth factor (PDGF) were significantly higher than those of other cases of AMM without FHT. The effusion did not respond to administrations of various chemotherapeutic agents, but after prednisolone administration, the effusion disappeared and the tumors also diminished. TGF-beta and PDGF were the possible causes of FHT formation, and for such fibrotic extramedullary regions, the administration of prednisolone should be considered.