The aim of this study was to evaluate the aetiology of 'unexplained' cytopenias in patients with autoimmune disorders, as well as to identify parameters that should alert clinicians to the need for bone marrow examination.

During the study period (2005-2010), 110 consecutive patients with an underlying systemic autoimmune disease, excluding Sjogren's syndrome, were referred for haematological consultation and bone marrow examination, due to cytopenias without evident cause including blood loss, haemolysis, nutritional deficiencies and haemoglobin disorders.

Systemic lupus erythaematosus was the most frequent underlying condition (38/110, 34.5%), and anaemia (haemoglobin<12gr/dl) the most common haematologic abnormality (81/110, 74%). Prior to evaluation, more than half of the patients received cytotoxic or immunosuppressive drugs, with methotrexate being the most commonly administrated agent (29/110, 26.4%). Evaluation was informative in 31 (28.2%) of the cases. Twenty-four (21.8%) cases of haematologic clonal disease were diagnosed; 11 myelodysplastic syndromes, 6 lymphoproliferative disorders, 6 plasma cell dyscrasias and one myeloproliferative neoplasm. Seven cases (6.4%) with bone marrow toxicity were also noted. Male gender, serum iron >90 μg/dl, mean corpuscular volume (MCV) >90fl, and serum monoclonal band were significant predictors of specific diagnosis including clonal haematologic disorder or bone marrow toxicity. All other correlations were insignificant.

Clonal haematologic disorders and toxicity are frequent findings in patients with autoimmunity referred for haematologic consultation, owing to otherwise unexplained cytopenias. Patients with high serum iron, high MCV and presence of serum monoclonal band should undergo bone marrow examination to exclude haematologic malignancy or bone marrow toxicity.