Abstract: SA-PO0782
Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposition (PGNMID) Misdiagnosed as Lupus Nephritis
Session Information
- Glomerular Diseases: Lupus Nephritis, Monoclonal Gammopathy-Related Disease, and Transplantation
October 24, 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
- McFarlane, Andrew, University Hospitals Health System, Cleveland, Ohio, United States
- Mustafa, Esraa S., University Hospitals St John Medical Center, Westlake, Ohio, United States
- Pradhan, Nishigandha, University Hospitals Health System, Cleveland, Ohio, United States
Introduction
PGNMID is a rare disease (biopsy incidence 0.17-3.7%1) with variable renal limited findings, absent serologic markers and negative tests for abnormal clones leading to a diagnostic challenge.
Case Description
A 26 year old male with history of CKD 3 due to Lupus Nephritis presented for emergent HD for severe acidosis and uremia. Prior kidney biopsy was read as LN class III/IV (Figure 1). Relevant laboratory findings are shown in Table 1. He was treated with cyclophosphamide, prednisone and MMF with maintenance prednisone and MMF, tapered 4 weeks before presentation. Absence of other clinical and biopsy features of SLE prompted repeat kidney biopsy (Figure 2), showing 2-3+ IF staining for IgG subtype 3, C3, C1q and kappa, suggestive of PGNMID. Treatment with daratumumab, dexamethasone and bortezomib was started despite negative hematologic testing; he continues to be dialysis-dependent.
Discussion
We describe a challenging case of PGNMID misdiagnosed as LN. Earlier accurate diagnosis could have enabled clonal specific chemotherapy with improvement of renal prognosis1. PGNMID should be suspected in patients with LN like histopathology without serologic markers or other systemic manifestations of SLE. IgG subtyping can be performed to confirm the diagnosis.
1. Bridoux F, et al, PGNIMD: a nephrologist perspective, Nephrol. Dial. Transplant., Vol 36, Iss 2, Feb 2021, pp. 208–215
Laboratory Testing
| Urinalysis | Urine Protein | Urine Protein Creatinine Ratio | ANA with reflex to ENA | C3 | C4 | Anti-dsDNA | Beta-2 glycoprotein IgG, IgA, IgM | Anti-SM /RNP | Lupus AC | PLA2R Ab | MPO Ab, IgG | PR3 Ab, IgG | ANCA IFA titer (c-ANCA and p-ANCA) | Anti-GBM antibody | HBV, HIV, HCV | CRP | ESR | ||
| Prior Admission | Protein 3+, Blood large, RBC 11-20/hpf, WBC 6-10/hpf | 1466 mg/dl | 8.94 (mg/mg) | Negative | 87 (wnl) | 31 (wnl) | <1 (neg) | 0.3 (neg) | <0.2 (neg) | <0.2 (neg) | <1:20 (neg) | <0.2 (neg) | Negative | 0.6 (wnl) | 80 (elevated) | ||||
| Current Admission | Protein 3+, blood 2+, RBC >20/hpf, WBC 21-50/hpf | >1000 mg/dl | Unable to calculate | Negative | 100 (wnl) | 44 (wnl) | <1 (neg) | Negative | <0.2 (neg) | Negative | <1:10 (neg) | 0 (neg) | 0 (neg) | <1:20 (neg) | 0 (neg) | Negative | 23 (elevated) | ||
LM: Cellular crescents with diffuse mesangial expansion and mesangial and endocapillary proliferation. IF: Diffuse, global, chunky granular mesangial and capillary loop staining for IgG, C3, kappa, lambda (all 3+) and C1q 1-2+
LM: Mesangial and endocapillary hypercellularity with cellular and fibrocellular crescents. IF: Granular mesangial and capillary wall staining for IgG, C3, C1q and kappa, all 2-3+; negative for lambda, IgA and IgM. IgG subclass staining negative for IgG 1, 2 and 4, strong positive for IgG3.