Multiple Myeloma Presenting as MPO-ANCA Associated Microscopic Polyangiitis

Reports on the association of multiple myeloma with systemic vasculitis are rare and concern, vasculitis due to crystalglobulin deposition in vessels or to polyarteritis nodosa PAN-like type necrotizing vasculitis. The association of multiple myeloma with MPO-ANCA positive microscopic polyangiitis has not yet been described. We report a case of a 72 year old man, who was referred to our clinic for evaluation of recent onset renal failure (serum creatinine 8mg/dl), proteinuria 2g/day, severe anemia (hematocrit 16%) and fever accompanied by malaise, anorexia, weigh loss, myalgia and arthralgia. These symptoms appeared 20 days prior to his admission. There was no evidence of any infection. The renal biopsy showed necrotizing crescentic glomerulonephritis. The MPO-ANCA were positive. Bone marrow biopsy revealed infiltration with IgG-lambda neoplastic plasma cells. The patient was treated with hemodialysis, plasma exchange, corticosteroids and cyclophosphamide. Even though his clinical situation and renal function improved gradually, two months after his admission, he developed acute respiratory insufficiency accompanied by heavy hemoptysis, patchy infiltration on chest X-rays, due to lung vasculitis and died. Multiple myeloma should be considered in the differential diagnosis of hematological neoplasms capable of causing paraneoplastic ANCA positive microscopic polyangiitis