The importance of the peripheral blood film in indicating a diagnosis of multiple myeloma with cryoglobulinaemia.

An independent 85-year-old male was admitted to the vascular surgery department with ischaemic toes initially attributed to atheroembolism in the setting of a known abdominal aortic aneurysm. His right great toe was amputated and he was discharged home with clopidogrel and aspirin. However, he re-presented with a decline in mobility and painful digits. Examination revealed marked acrocyanosis of all his digits (left) A blood count showed haemoglobin concentration 105 g/l, leucocytes 6·3 × 109/l and platelets 310 × 109/l. Blood film examination revealed multiple large extracellular crystals with numerous smaller crystals (right). An immunoglobulin (Ig) G kappa paraprotein (17 g/l) was identified together with elevated kappa free light chain (190 mg/l) and kappa: lambda ratio (8·3). Given the clinical presentation of acrocyanosis, the crystals were thought to be cryoglobulin. A bone marrow aspirate showed more than 40% abnormal, kappa-restricted plasma cells. There was no renal impairment and skeletal survey did not show any lytic lesions. Mild hypercalcaemia (2·78 mmol/l) was present. A diagnosis of IgG kappa multiple myeloma presenting with cryoglobulinaemic vasculitis was made. The patient was commenced on treatment with dexamethasone, bortezomib and cyclophosphamide with significant clinical improvement. The serum cryoglobulin assay eventually confirmed the presence of a monoclonal IgG kappa cryoglobulin at a concentration of 19·8 g/l. This case highlights the value of blood film examination. Identification of the crystals in the blood film rapidly led to further testing and diagnosis so that treatment was commenced before the standard cryoglobulin serum testing results were available. Cryoglobulin testing involves at least two 72-h refrigeration steps, an incubation at 37°C and, finally, immunofixation and quantification. In our experience, turnaround time on urgent samples is a minimum of 7 days and often over 2 weeks. Expediting the diagnosis and treatment in this case potentially saved further tissue damage and improved the patient's outcome. Supplementary images show the bone marrow aspirate and the patient's hands post-treatment. Fig. S1. Bone marrow film. Fig. S2. Patient's hands post treatment. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.