Unusual case of levamisole-induced dual-positive ANCA vasculitis and crescentic glomerulonephritis.

Cocaine adulterated levamisole is an increasingly reported cause of skin necrosis, arthralgia and systemic vasculitis, but renal involvement is uncommon. We present a case of a 40-year-old Hispanic man with a history of cocaine abuse who presented with acute kidney injury to the rheumatology clinic where he was being treated for chronic inflammatory arthritis. He was found to have a serum creatinine of 2.5 mg/dL, microscopic haematuria and subnephrotic proteinuria, along with positive proteinase 3, myeloperoxidase, anticardiolipin antibodies and an elevated antinuclear antibody titre. The renal pathology revealed focal necrotising glomerulonephritis with crescentic features and mild immune type deposition. The patient was treated with cocaine abstinence, pulse dose steroids followed by maintenance prednisone, rituximab and cyclophosphamide. His renal function subsequently improved but did not normalise. We believe that his incomplete improvement was due to the degree of kidney injury on presentation as well as recidivism with cocaine use.