RT Book, Section A1 Manno, Rebecca L. A1 Yazdany, Jinoos A1 Tarrant, Teresa K. A1 Kwan, Mildred A2 Papadakis, Maxine A. A2 McPhee, Stephen J. A2 Rabow, Michael W. A2 McQuaid, Kenneth R. SR Print(0) ID 1193125843 T1 Levamisole-Associated Purpura T2 Current Medical Diagnosis & Treatment 2023 YR 2023 FD 2023 PB McGraw-Hill Education PP New York, NY SN 9781264687343 LK accessmedicine.mhmedical.com/content.aspx?aid=1193125843 RD 2024/11/05 AB Exposure to levamisole, a prevalent adulterant of illicit cocaine in North America, can induce a distinctive clinical syndrome of retiform purpura and cutaneous necrosis affecting the extremities, ears, and skin overlying the zygomatic arch. The syndrome has been linked to neutropenia, agranulocytosis, and pauci-immune glomerulonephritis. It is associated with the lupus anticoagulant, IgM antibodies to cardiolipin, and very high titers of p-ANCAs (due to autoantibodies to elastase, lactoferrin, cathepsin-G, and other neutrophil components rather than to myeloperoxidase alone). Biopsies reveal widespread thrombosis of small cutaneous vessels with varying degrees of vasculitis. There is no consensus on treatment of levamisole-induced purpura, but early lesions can resolve with abstinence. There may be long-term sequelae of levamisole exposure, such as deforming cutaneous lesions, arthralgias, and arthritis.