Cocaine-induced ANCA-associated renal disease: a case-based review.

Idiopathic antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a group of diseases that are often difficult to diagnose due to the wide range of clinical manifestations. Notably, renal involvement is a serious organ complication, which usually requires intensive immunosuppressive therapy and is prone to recurrence. In recent years, there has been some progress regarding the understanding of the pathogenesis of the diseases. It has been shown that both cocaine and levamisole, which is a common adulterant of cocaine, can trigger the formation of ANCAs and lead to the corresponding symptoms. We report two cases of AAV with different renal manifestations associated with cocaine consumption. Furthermore, we performed a review of the literature to identify, characterize and describe histologically documented cases of renal involvement in AAV, related to cocaine abuse. Cocaine/levamisole-induced vasculitis may, therefore, mimic idiopathic AAV. Although the detection of ANCA and anti-PR3 (proteinase 3, PR3) as well as anti-MPO antibodies (myeloperoxidase, MPO) are the serological hallmark of idiopathic AAV, certain clinical- and antibody constellations should lead to consideration of illicit drugs as inductors of the disease. Especially in young patients, certain serologic constellations (e.g., PR3 and MPO double positivity, positive antinuclear antibodies, low complement level, and positive testing for antiphospholipid antibodies), skin involvement, musculoskeletal symptoms and hematologic (anemia, leukopenia) affections should prompt testing for cocaine and levamisole consumption via urine drug testing. Treatment includes both immunosuppressive approaches and drug cessation but is difficult since many patients continue cocaine consumption.