Pulmonary-Renal Syndrome in ANCA-Associated Vasculitis Requiring Extracorporeal Membrane Oxygenation

Introduction: Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a rare autoimmune disorder that can manifest with rapidly progressive glomerulonephritis (RPGN) and diffuse alveolar hemorrhage (DAH). This report describes a patient with AAV complicated by refractory hypoxemia, requiring veno-venous extracorporeal membrane oxygenation (VV-ECMO). Case Description: A 59-year-old woman with heart failure with reduced ejection fraction, hypertension, hyperlipidemia, and hypothyroidism presented with four months of fatigue, weight loss, anorexia, two weeks of hematuria and arthralgias, and a subacute creatinine rise from 0.78 to 3.02mg/dL. Exam showed vitals within normal limits and bilateral inspiratory crackles. Labs included hemoglobin 6.8g/dL, creatinine 4.2mg/dL, calcium 15.6mg/dL, PTH wnl, PTHrP 3.8pmol/L, urinalysis with >100 RBCs/HPF and >10 WBCs/HPF, UPCR 4.98mg/mg, ESR 97mm/hr, CRP 94.9mg/L, negative SPEP, kappa/lambda ratio 1.85. Chest CT showed bilateral ground glass opacities and a 9 mm spiculated left upper lobe nodule. Hepatitis B, C, and HIV were negative. A recent PET scan had shown a T10 osseous lesion. During hospitalization, she developed hemoptysis raising concern for AAV. She was admitted to the ICU for airway watch and started on pulse-dose IV methylprednisolone. She was then transferred to our facility where she completed pulse dose steroids. Workup was positive for pANCA, >1:1280, anti-myeloperoxidase antibodies (MPO) 90 AU/mL, and proliferative crescentic glomerulonephritis on kidney biopsy. She underwent induction therapy with rituximab, however later developed recurrent hemoptysis complicated by hypoxemic respiratory failure. Bronchoscopy revealed diffuse alveolar hemorrhage. She was intubated and started on VV-ECMO for refractory hypoxemia. After receiving further IV methylprednisolone, seven cycles of plasmapheresis, and completing rituximab induction therapy, she was ultimately extubated, weaned off ECMO, and discharged on dialysis and a prednisone taper. Discussion: This case highlights the rare need for VV-ECMO in AAV-related DAH, demonstrating successful outcomes with aggressive immunosuppression and supportive care. Imaging and lab findings also suggest a potential occult malignancy, raising the rare consideration of paraneoplastic AAV pending further workup.