20. Cocaine: The Vasculitis Mimic

Abstract

Background: Drug-induced vasculitis is the commonest cause of vasculitis in adults. Differentiating drug-induced from the idiopathic vasculitis syndromes can be challenging. ANCA positivity can be associated with both idiopathic and drug-induced vasculitis. Levamisole, an antihelminthic agent with immunomodulating properties has been associated with drug-induced vasculitis. Levamisole is used as a cocaine-adulterating agent and the development of ANCAassociated vasculitis syndromes with cocaine use has recently been recognized. We describe two cases of cocaine-induced vasculitis with typical ANCA positivity. Methods: Case 1: a 51 year old male presented with acute onset auricular inflammation progressing to cartilagenous necrosis, polyarticular symmetrical synovitis and digital necrosis. Immunofluorescence demonstrated a positive p-ANCA pattern with high titre myeloperoxidase antibodies (MPO) of 33.7U/ml (normal range 0-5 U/ml). He was commenced on oral prednisolone by the admitting team. After direct questioning the patient admitted to being a long-standing cocaine abuser with his most recent cocaine use 3 days prior to presentation. His clinical features improved spontaneously and his steroids were withdrawn. However, he represented with further auricular necrosis and polyarthritis 3 months later after a further cocaine binge. He was advised to remain abstinent and on review 6 months post-presentation, he had no features of active vasculitis. Case 2: a 33 year old male cocaine abuser presented with pericarditis, a widespread maculopapular rash, polyarthritis and recurrent sinus symptoms. He had a raised CRP of 83mg/l (normal range 0-5mg/l) and an eosinophilia of 2.5×109/l (0- 0.4×109/l). Electrocardiogram and echocardiogram were consistent with pericarditis and a significant pericardial effusion. Treatment was introduced with NSAIDs. ANCA was positive in a cytoplasmic pattern (c- ANCA) with high titre of >100U/ml (normal range 0-5 U/ml) directed to proteinase 3 (PR3) antibodies. The patient admitted to a 10-year history of cocaine abuse with most recent cocaine inhalation 6 weeks prior to presentation. Treatment with oral steroids was initially introduced but rapidly weaned when the history of cocaine use was appreciated. At 6-month follow-up after cocaine abstinence the patient remained well and the PR3 titre reverted to negative. Results: Levamisole-adulterated cocaine during recreational drug abuse is a recently described clinical mimic of idiopathic vasculitis syndromes. Both our patients displayed features which could have been associated with the idiopathic syndromes and the specific serology added to the diagnostic difficulty. In both cases withdrawal of the drug with avoidance of significant immunosuppression occurred resulting in clinical improvement. Pathophysiological mechanisms of this clinical entity will be discussed. Conclusion: All patients presenting with vasculitis syndromes should be interrogated for cocaine use even when specific serological testing is positive.