Atypical ANCA+ Diffuse Alveolar Hemorrhage (DAH) Secondary to Cannabis Vaping

Abstract

Background:Diffuse alveolar hemorrhage (DAH) is a rare, life-threatening condition that can cause hemoptysis and acute respiratory failure. The underlying pathology is highly variable, which often makes finding a definitive cause challenging. Case Description: A 29-year-old female with a history of intermittent blood-tinged sputum and lower extremity rash presented with dyspnea and hemoptysis, requiring intubation. Chest CT revealed ground-glass opacities. Bronchoscopy revealed DAH. Other notable findings were anemia, thrombocytopenia, atypical p-ANCA+ 1:160 with negative MPO and PR3, elevated CRP and ESR, and hematuria and proteinuria with baseline kidney function. The patient also developed bilateral pulmonary embolisms. Extensive infectious and rheumatologic workup were otherwise unremarkable. Clinical improvement was evident after treatment with steroids. Conclusions:This case illustrates a presentation of atypical p-ANCA+ DAH that was likely induced by vaping marijuana, highlighting the importance of having a broad differential for DAH, specifically in distinguishing vasculitis and drug-induced causes. Granulomatosis with polyangiitis (GPA) is a small-medium vessel vasculitis with diagnostic criteria including bloody nasal discharge, pulmonary involvement, and glomerulonephritis. Lab tests reveals c-ANCA+ and PR3+ around 80-90% of the time. In this case, lab results revealed atypical p-ANCA+, which is not associated with vasculitis. Due to considering a wide differential in a case that mimicked GPA, this patient was spared unnecessary immunosuppressive therapy. Clinical Significance: Of clinical significance, marijuana is the most common illicit substance used in the United States. This case highlights the importance of placing drug-induced DAH among the more traditional differentials associated with this acute clinical presentation. This case report aims to raise awareness and improve the efficiency of clinical diagnosis and treatment of cannabis-induced DAH that mimics clinical findings of GPA.