Cocaine–Levamisole-Associated Vasculopathy Mimicking ANCA-Associated Vasculitis and Presenting With Pulmonary–Renal Syndrome Requiring VV-ECMO Support

Rare disease Background:Levamisole, a widely used adulterant in illicit cocaine, has emerged as an important cause of cocaine-levamisole-associated vasculopathy (CLAV), a syndrome that can mimic primary ANCA-associated vasculitis.Typical features include neutropenia, atypical ANCA patterns, thrombotic manifestations, diffuse alveolar hemorrhage (DAH), and crescentic glomerulonephritis (GN).Dual MPO-PR3 ANCA positivity is strongly suggestive of druginduced vasculopathy. Case Report:We report the case of a 30-year-old woman presenting with hemoptysis, anemia, and diffuse pulmonary infiltrates.Laboratory evaluation demonstrated hematuria, proteinuria, and dual MPO/PR3 ANCA positivity.Renal biopsy showed necrotizing crescentic GN, and urine toxicology confirmed cocaine exposure.She received pulse corticosteroids and rituximab.Three days after early discharge, she returned with massive hemoptysis and respiratory failure.Bronchoscopy confirmed DAH, and arterial blood gases demonstrated refractory hypoxemia with a PaO 2 /FiO 2 ratio below 80 despite maximal ventilatory support.Plasmapheresis was initiated, followed by veno-venous extracorporeal membrane oxygenation (VV-ECMO) for worsening respiratory acidosis and persistent hypoxemia.Cyclophosphamide was added when her condition stabilized.Her respiratory status gradually improved, she was decannulated from ECMO, and renal function normalized.At 18 months, she remained in remission with minimal residual pulmonary abnormalities despite persistent MPO-ANCA positivity. Conclusions:This case highlights CLAV as a severe vasculopathic mimic of ANCA-associated vasculitis.Early recognition, cessation of cocaine use, appropriate immunosuppression, and timely escalation to VV-ECMO when indicated are critical for survival in fulminant DAH.