Kidney Week

Abstract: SA-PO780

I ANCA Kidding: ANCA-Associated, Pauci-Immune Crescentic Glomerulonephritis with Normal Kidney Function Presenting with Transverse Myelitis

Session Information

• ANCA-Associated Vasculitis, Anti-GBM Disease, and Other RPGN
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Yen, Timothy E., The University of Mississippi Medical Center, Jackson, Mississippi, United States

Timothy E. Yen, MD

• Tio, Maria Clarissa, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Maria Clarissa Tio, MD, MPH, FASN

• Velagapudi, Ramya Krishna, The University of Mississippi Medical Center, Jackson, Mississippi, United States

Ramya Krishna Velagapudi, MD

• Dossabhoy, Neville R., The University of Mississippi Medical Center, Jackson, Mississippi, United States

Neville R. Dossabhoy, MD, FASN

Introduction

Microscopic polyangiitis (MPA) frequently (>80%) manifests with kidney involvement, often presenting with rapidly progressive glomerulonephritis. However, MPA can have a variable presentation with normal kidney function, underscoring the importance of recognizing the extrarenal manifestations of the disease.

Case Description

A 63-year-old Black female was admitted with a 2-week history of falls and progressive lower extremity weakness. Vital signs and electrolytes were normal with creatinine at a baseline of 0.8 mg/dL. Spinal MRI revealed longitudinally extensive transverse myelitis extending from the corticomedullary junction to the thoracic cord. A broad workup for inflammatory, neoplastic, and infectious etiologies was performed and revealed positive ANA (1:320), anti-RNP (1.2U), and anti-myeloperoxidase (1.5U) autoantibodies with P-ANCA positivity raising the concern for MPA with CNS involvement. The patient started plasma exchange (x6) and pulse steroids before being tapered to 1 mg/kg.
Despite normal creatinine, nephrology was consulted due to hematuria (RBC >100) and pyuria (WBC >500) on urinalysis and 0.4g/g UPCR. Further, CT chest done for trauma/fall evaluation had revealed asymptomatic lung infiltrates which together with ANCA and renal findings raised concern for a pulmonary-renal syndrome. A transbronchial biopsy was performed first. The initial pathology report from our institution suggested capillaritis, but a second, specialty evaluation reported no vasculitis. The patient subsequently underwent a kidney biopsy which showed pauci-immune crescentic glomerulonephritis (5/20 glomeruli with crescents--3 fibrocellular/2 fibrous crescents; negative immunoglobulins and complements on immunofluorescence) with minimal (~5%) interstitial fibrosis/tubular atrophy. These findings were consistent with MPA and a rituximab-based regimen was started. At four months, the patient’s neurologic sequelae have completely resolved while her kidney function has remained at baseline.

Discussion

Although MPA commonly involves the peripheral nervous system, severe central nervous system manifestations such as transverse myelitis are uncommon. In this case, early recognition of the underlying pulmonary-renal syndrome was crucial to ensuring adequate therapy and preserving kidney function.