Abstract: FR-PO0796
Pauci-Immune Crescentic Glomerulonephritis in the Setting of ANCA Positivity and Late Latent Syphilis
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
- Anwar, Amna, Jefferson Einstein Philadelphia Hospital, Philadelphia, Pennsylvania, United States
- Elrefy, Omar A., Jefferson Einstein Philadelphia Hospital, Philadelphia, Pennsylvania, United States
- Chewaproug, Daranee, Jefferson Einstein Philadelphia Hospital, Philadelphia, Pennsylvania, United States
- Ahmed, Zahoor, Jefferson Einstein Philadelphia Hospital, Philadelphia, Pennsylvania, United States
Introduction
ANCA-associated vasculitis commonly presents as pauci-immune crescentic glomerulonephritis. Infections such as syphilis may mimic autoimmune disease clinically and serologically, complicating diagnosis and management.
Case Description
A 79-year-old legally blind male with CKD stage 3, benign prostatic hyperplasia, and interstitial lung disease on chronic prednisone presented with recurrent falls and AKI. Serum creatinine increased from 1.8 mg/dL to 5.54 mg/dL, with microscopic hematuria and proteinuria of 2.1–2.5 g/g. Serologic evaluation showed positive p-ANCA (1:640), MPO (267.3), ANA (1:1280), dsDNA, anti-Smith, and anti-RNP antibodies with normal complement levels. Treponemal antibodies were reactive with nonreactive RPR, concerning for late latent syphilis. CT chest demonstrated usual interstitial pneumonia pattern and diffuse lymphadenopathy. Kidney biopsy revealed pauci-immune crescentic glomerulonephritis with 8/19 glomeruli showing active crescents and moderate-to-severe interstitial fibrosis and tubular atrophy. IF and EM showed no significant immune deposits.
Despite chronic prednisone use before presentation, he required pulse steroids followed by rituximab and prednisone taper per PEXIVAS protocol. Given prior hepatitis B exposure, tenofovir and atovaquone prophylaxis were initiated before immunosuppression. Penicillin therapy was started for late latent syphilis. Although syphilis-associated ANCA positivity and crescentic glomerulonephritis were considered, biopsy findings favored ANCA-associated vasculitis. He remained dialysis-independent.
Discussion
Syphilis may mimic autoimmune disease and has been associated with positive ANCA and other autoantibodies. Rare cases of syphilis-associated crescentic glomerulonephritis have also been described, creating diagnostic uncertainty in this patient.
Despite concern for infection-related glomerular disease, the kidney biopsy demonstrated a pauci-immune process lacking immune deposits, favoring ANCA-associated vasculitis. The case was further complicated by worsening renal function despite chronic prednisone use and prior hepatitis B exposure, requiring antiviral prophylaxis before rituximab therapy.
This case highlights the essential role of kidney biopsy in distinguishing infection-related glomerulonephritis from ANCA-associated vasculitis and emphasizes careful infectious evaluation before long-term immunosuppression.