Polycythaemia vera: bone marrow histopathology under treatment with interferon, hydroxyurea and busulphan.

Little is known about long-term effects of myelosuppressive therapy on bone marrow of patients with polycythaemia vera, since histopathology from follow-up biopsies has not been frequently reported. Thus we conducted a retrospective morphometrical analysis of diagnostic and follow-up biopsies of 62 patients, evaluating fibre content, megakaryocytes and bone marrow cellularity. 8/62 patients were treated with interferon-alpha (INF), 11/62 with hydroxyurea (HU) and 11/62 with busulphan (BU). 32/62 served as controls; they were not treated with myelosuppressive drugs but with phlebotomy only. The median observation time was 2.3 yr. Results were compared on the basis of change per time. The bone marrow of the patients with phlebotomies only was characterised by increasing cellularity of haematopoesis, number and volume ratio of megakaryocytes and fibre content. In BU- and HU-treated patients, the haematopoesis was significantly reduced. The IFN patients revealed a reduction of cellularity which was not significant. The fibre content was reduced by BU only, but not significantly. No correlation between megakaryocytes and fibres was found. It could be concluded therefore that: 1) fibre proliferation within the bone marrow was not significantly altered by IFN, HU or BU. 2) Cellularity of haematopoesis was reduced significantly by HU and BU but only partly by IFN, corresponding with haematological remission.