Abstract Microscopic polyangiitis (MPA) is a pauci-immune small-vessel vasculitis most commonly associated with myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA). It frequently presents with rapidly progressive glomerulonephritis (RPGN) and diffuse alveolar hemorrhage (DAH), both markers of increased morbidity and mortality. While high-dose corticosteroids with rituximab or cyclophosphamide remain standard therapy, the role of plasma exchange (PLEX) is evolving, with selective benefit suggested in cases of severe renal dysfunction and hypoxemic DAH. A 70-year-old woman with estrogen/progesterone receptor-positive invasive lobular carcinoma in remission, type 2 diabetes presented five days after discharge for presumed community-acquired pneumonia. During the prior admission, creatinine rose from 1.0 to 3.6 mg/dL with frank hematuria, though opacities in the right upper lobe were attributed to infection. On readmission, she appeared fatigued but hemodynamically stable with O2 saturation 94% on 2 L nasal cannula. Laboratory results showed Cr 4.66 mg/dL, BUN 31 mg/dL, Hgb 8.6 g/dL (from 13 g/dL baseline), and urinalysis positive for dysmorphic RBCs and 3+ protein. CXR demonstrated new bilateral patchy infiltrates. Empiric broad-spectrum antibiotics were initiated. Over the next 48 hours, she experienced rapid respiratory decline with increasing oxygen requirement to 14 L HFNC, diffuse crackles, and escalating bloody secretions. CT chest revealed diffuse bilateral ground-glass opacities. Bronchoscopy confirmed DAH with bloody return from serial aliquots and clot burden requiring suctioning. She was intubated for hypoxemic respiratory failure, and methylprednisolone 1 g/day x3 days was initiated. MPO-ANCA level was 217 U (normal 20), PR3 negative. Renal biopsy showed cellular crescents in 50% of glomeruli without immune-complex deposition, consistent with pauci-immune crescentic glomerulonephritis. Hemodialysis was started due to rising creatinine (peak 6.46 mg/dL) and concern for uremic platelet dysfunction. Plasma exchange was initiated daily. Cyclophosphamide was administered on hospital day 7 followed by rituximab on day 9, timed around PLEX and HD sessions. After the fourth PLEX session, her oxygenation improved with cessation of hemorrhage and decreased bloody airway secretions. She was extubated successfully and dialysis was discontinued by hospital day 17 with improving urine output. At four-week follow-up, creatinine improved to 3.1 mg/dL with adequate urine output, and she remained oxygen-independent while transitioning to avacopan-based maintenance therapy.While PLEX is no longer recommended routinely for all cases of ANCA-associated vasculitis, this case demonstrates that it remains an important adjunct in selected patients presenting with concurrent DAH and advanced renal dysfunction. Tailoring therapy to disease severity, patient comorbidities, and evolving evidence can optimize outcomes in life-threatening presentations of MPA This abstract is funded by: none
Sharif et al. (Fri,) studied this question.