Abstract: FR-PO0771
ANCA-Associated Pauci-Immune Glomerulonephritis and Breast Cancer
Session Information
- Glomerular Diseases: ANCA Vasculitis, Anti-GBM Disease, and Crescentic GN
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- El Masri, Bilal, MedStar Health Georgetown University, Baltimore, Maryland, United States
- Jaar, Bernard G., The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Ghandour, Elias C., Nephrology Center of Maryland, Baltimore, Maryland, United States
Introduction
ANCA-associated vasculitis (AAV) is a well-known cause of pauci-immune crescentic glomerulonephritis. However, ANCA positivity may also occur in malignancy, raising concern for a paraneoplastic process that complicates diagnosis and management, particularly when immunosuppression carries substantial risk.
Case Description
A 79-year-old woman with chronic kidney disease G3a (baseline creatinine 1.19 mg/dL), hypertension, type 2 diabetes, and recently diagnosed papillary breast cancer on letrozole presented with severe acute kidney injury (creatinine 5.17 mg/dL), microscopic hematuria, and proteinuria (UPCR 1.58 mg/mg). Blood pressure was 222/87 mmHg. Serologies showed ANA 1:160 and high-titer MPO-ANCA (>1:1280; MPO 79 U). Other tests were unrevealing. Kidney biopsy revealed focal pauci-immune crescentic glomerulonephritis with 1 fibrocellular crescent among 25 glomeruli, along acute tubular injury (ATI), hypertensive microangiopathy, diabetic nephropathy, and 30% interstitial fibrosis. She received methylprednisolone (250 mg IV daily for 3 days). Given limited crescentic involvement and active malignancy, further immunosuppression was deferred after shared decision-making (SDM). At 3-month follow-up, kidney function and proteinuria improved (creatinine 4.02 mg/dL, UPCR 0.857 mg/mg).
Discussion
This case highlights discordance between high MPO-ANCA titers and limited histopathologic glomerular injury in active malignancy. Although ANCA positivity in cancer may reflect a paraneoplastic phenomenon, pathogenicity remains possible, and biopsy sampling may underestimate disease burden. Minimal crescentic involvement and malignancy favored conservative management. Clinical improvement suggests a multifactorial process, with ATI and hypertensive microangiopathy contributing substantially. Kidney biopsy remains essential for diagnosis, prognosis, and SDM in patients with malignancy and suspected glomerular disease.
Partial fibrocellular crescent (methenamine silver)