AB1377 Clinical interest of bone marrow examination in rheumatology practice: An observationnal study of 257 patients

Background Examination of the haematopoietic marrow is essential in the diagnosis of many disorders, principally malignant haematological diseases which can be encountered in rheumatology practice. Bone marrow aspiration (BMA) and biopsy (BMB) is thus principally performed by rheumatologists for diagnostic purposes to determine the origin of a monoclonal peak discovered on serum protein electrophoresis (SPE) or the cause of a quantitative or qualitative abnormality in hemogram associated with musculoskeletal symptoms. Objectives The aim of the study was to evaluate professional practices of hospital-based rheumatologists with regard to BMA and BMB in order to identify the clinically relevant indications in this context. Methods Retrospective single-centre observational study in patients hospitalised in a University Hospital’s Rheumatology department between 2005 and 2011.All of the patients who had a BMA and BMB for diagnostic purposes in the Rheumatology Department during the period above were included. Clinical indication, numbers, results of BMA and BMB were collected and treatment of the haematological disease implemented following the results were described. Results 257 BMA (annual mean: 36.7±9.2) and 79 BMB (annual mean: 11.3±6.2) were performed in the Rheumatology Department. 14.1% of BMA were pathological: multiple myeloma (n=12), malignant B-cell non-Hodgkin’slymphoma (NHML) (6), myelodysplastic syndrome (6), chronic lymphoid leukaemia (4), Waldenstrom’s disease (3), chronic myelomonocytic leukaemia (2), hairy cells leukaemia (1) and acute lymphoblastic leukaemia (1). 8 pathological BMB were associated with normal BMA: three adenocarcinomas, 2 NHML type B, 1 myeloid splenomegaly, 1 amyloidosis and one tuberculous osteomyelitis.BMA were performed equally (54% vs. 46%, p=0.12) for gammaglobulin abnormalities (monoclonal peak=45% of indications, hypogammaglobulinemia =6%, oligoclonal profile on SPE=3%) and for other reasons (hemogram abnormality=24%, skeletal tumor=6%, inflammatory syndrome=5%, lymp-node disease=4%, suspected vertebral fracture=3%, chronic inflammatory rheumatism with deterioration in health status=3% and others). The diagnostic rentability of BMA varied considerably: excellent in cases where a monoclonal peak was associated with osteolysis or hypercalcemia (>2/3 of myeloma), moderate in cases of isolated peak (8% of pathological BMA), hypogammaglobulinemia (13%) or hemogram abnormality (14%) but almost zero if the indication was based exclusively on the clinical context and on inflammatory syndrome. Conclusions In this practice-based observational study, BMA may reveal two major types of malignant haematological diseases: advanced-stages myeloma justifying polychemotherapy and autologous grafts and, in contrast, slowly-evolving B-cell lymphoid haemopathies which only require clinical and biological surveillance. In certain specific situations (undetermined bone or lymph-node lesion, persistent inflammatory syndrome), BMB should be performed more frequently than observed. In rheumatology practice, apart from distinguish monoclonal gammopathy of undetermined significance and myeloma, bone marrow examination can be a valuable procedure to rule out certain types of B-cell malignant haemopathy among which lymphoma is probably the most feared, given the additional risk in some chronic inflammatory rheumatic diseases. Disclosure of Interest None Declared