Inflammatory rheumatic diseases and the applied immunosuppressive treatments can lead to bone marrow depressions and promote hematologic malignancies. Our objective was to explore indications for and results of bone marrow examinations in a large cohort.

Between 1990 and 2004 146 bone marrow examinations in 3638 patients were performed due to abnormal laboratory results. Medical history, results of bone marrow examination (morphology, histology) and cytogenetic data were investigated retrospectively.

Patients' (67.8% female) mean age at bone marrow examination was 53.5 years (SD 15.5), median disease duration 2.9 years. Indications for bone marrow examination were changes in peripheral blood counts in 81.7%. In 52 patients (35.6%) clinically relevant, partially neoplastic bone marrow changes (5 non-Hodgkin lymphoma, 9 myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML) and 3 myeloproliferative neoplasias) were evident. Medication history showed intake of hydroxy-/chloroquine (13.5%), methotrexate (17.3%), cyclosporin (7.7%), sulfasalazine (7.7%), mycophenolatmofetil, gold, leflunomide (each 1.9%), azathioprine (aza, 25.0%) or cyclophosphamide (cyc, 7.7%) prior to bone marrow examination. 7 out of 9 patients, who developed MDS/AML had been treated with either azathioprine alone or additionally with cyclophosphamide (n = 3).

One third of our patients showed relevant bone marrow changes that might be associated to therapy. The risk seems to be increased especially in patients with inflammatory rheumatic diseases who had received azathioprine alone or in combination with cyclophosphamide. Health care providers should bear in mind the risk of hematologic malignancies and monitor patients closely in this respect. Bone marrow examination should be performed in case of changes in peripheral blood counts; especially clinically relevant anemia, granulocytes < 2,500/microl, thrombocytes < 100,000/microl and relevant changes over time should lead to bone marrow examinations.