A 63-year-old man presented to his general practitioner with a 12-month history of ‘a recurrent purpuric rash’ on both lower limbs. The clotting screen was normal. Full blood count showed haemoglobin 14·3 g/dl, white count 12·5 × 109/l, neutrophils 9·7 × 109/l, lymphocytes 2·5 × 109/l, platelets 277 × 109/l, erythrocyte sedimentation rate 7 mm/h. Neutrophil vacuolation had been noted on previous blood films although the significance of this feature had not been appreciated. Closer inspection of the vacuolation revealed an unusual pale blue amorphous material within the vacuoles as well as extracellular deposits of similar material (top). Ultrastructural examination confirmed these findings (bottom). The clinical impression was that of a cryoglobulinaemia, which was subsequently confirmed by the demonstration of an IgG kappa monoclonal cryoglobulin. There was no associated immune paresis and complement levels were normal. The biochemical profile was normal and hepatitis and autoimmune screens were all negative. A bone marrow examination was refused. A skin biopsy confirmed necrotizing leucocytoclastic vasculitis and the patient was started on low-dose prednisolone and oral cyclophosphamide. The lesions have completely resolved, as has the neutrophil vacuolation, concomitant with a significant decrease in paraprotein levels.