Cocaine-induced ANCA-associated vasculitis: Cohort analysis from a referral center and literature review.

Abstract

Cocaine adulterated with levamisole has been implicated as a trigger of Cocaine-Levamisole-Associated Autoimmune Syndrome (CLAAS), frequently mimicking granulomatosis with polyangiitis (GPA). To characterize the clinical, serologic, and histopathologic features of CLAAS and compare them with GPA. Retrospective analysis of 194 patients diagnosed with ANCA-associated vasculitis between 2000-2024 at a referral center in Northern Spain. Classification followed the 2022 ACR/EULAR criteria. ANCA serologies were assessed by chemiluminescence. Ten patients (5.15%) were identified as having CLAAS via self-report or urine toxicology. A comparative analysis with GPA (n=64) and a structured literature review (2015-2025) were conducted. CLAAS cases had a mean age of 49.9±10.4 years and a female predominance (70%). Otolaryngologic (ENT) manifestations were prominent, frequently accompanied by septal perforation and midline destructive lesions. Articular symptoms occurred in 40%, and renal involvement in 20%, including one biopsy-proven crescentic glomerulonephritis. All were ANCA-positive, predominantly PR3+ (80%), and 30% showed anti-neutrophil elastase antibodies. ENT biopsies showed inflammatory but non-vasculitic changes; these findings were supportive but not pathognomonic for CLAAS. Treatments included corticosteroids, methotrexate, and rituximab, with remission strongly associated with cocaine abstinence. Compared with GPA, CLAAS cases showed more extensive ENT and cutaneous involvement, higher rates of dual ANCA positivity, and elastase reactivity. CLAAS is a distinct clinicopathologic entity that overlaps with GPA but differs in histopathology, therapeutic response, and prognosis. Accurate diagnosis requires integrating toxicologic testing and recognizing substance-use patterns.