Abstract: TH-PO795
ANCA-Associated Kidney Disease in a Child with History of Presumed IgG4-Related Disease
Session Information
- Pathology and Lab Medicine - I
November 02, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1800 Pathology and Lab Medicine
Authors
- Oleson, Ileisa, Oregon Health & Science University, Portland, Oregon, United States
- Fecker, Adeline L., Oregon Health & Science University, Portland, Oregon, United States
- Richardson, Kelsey L., Oregon Health & Science University, Portland, Oregon, United States
- Bauer, Abbie R., Oregon Health & Science University, Portland, Oregon, United States
- Andeen, Nicole K., Oregon Health & Science University, Portland, Oregon, United States
- Kung, Vanderlene Liu, Oregon Health & Science University, Portland, Oregon, United States
Introduction
Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and IgG4-related disease (IgG4-RD) are immune disorders with distinctions in pathogenesis, prognosis, and management, that can share clinical and laboratory features. While ANCA positivity excludes IgG4-RD in the 2019 ACR/EULAR classification, this criterion is not uniformly applied, and AAV can form inflammatory masses in various organs and show increase in IgG4+ plasma cells, similar to IgG4-RD. This case highlights challenges in AAV and IgG4-RD diagnoses in a child.
Case Description
A 5-year-old female with previously normal kidney function presents with nausea, diarrhea and acute kidney injury with hematuria and proteinuria. Her only medical history is of a left orbital mass a year ago, diagnosed as IgG4-RD based on elevated serum IgG (1270 mg/dL) and biopsy with sclerosing fibrosis with IgG4+ plasma cells and eosinophils, and treated with steroids with complete mass resolution.
On this admission, she has a positive MPO ANCA (1:80) with pertinent negatives of normal serum C3, C4, total IgG, and IgG4, and negative ANA and anti-dsDNA. A kidney biopsy shows chronic active pauci-immune crescentic glomerulonephritis and acute tubulointerstitial nephritis with up to 14 IgG4+ plasma cells/40X field, IgG4+/IgG+ plasma cell ratio up to 25%, and focal tubular basement membrane (TBM) deposits (Image). She is treated with pulse steroids and rituximab with no kidney function improvement, in contrast to most cases of IgG4-RD.
Discussion
Pauci-immune crescentic GN with positive ANCA are characteristic for kidney AAV, and in retrospect, suggest the orbital mass may have represented the initial manifestation of AAV despite orbital mass histology with increased IgG4+ plasma cells and elevated serum IgG4 at diagnosis. The additional features of TBM deposits and increased IgG4+ plasma cells in the kidney biopsy highlight further potential for confounding morphologic overlap between AAV and IgG4-RD, for which correlation with ANCA testing is essential.