Abstract: SA-PO0965
Rare Kidney Diseases Associated with Monoclonal IgG2 Immunoglobulin Deposition: A Multi-Institutional Retrospective Study
Session Information
- Pathology: Updates and Insights
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1800 Pathology and Lab Medicine
Authors
- Feng, Xiuyan, University of Colorado System, Denver, Colorado, United States
- Wang, Yihan, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Salvatore, Steven, Weill Cornell Medicine, New York, New York, United States
- Yang, Haichun, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Yang, Yihe, Weill Cornell Medicine, New York, New York, United States
Introduction
Monoclonal immunoglobulin-associated kidney diseases are rare entities with diverse pathological findings that can be challenging to classify. Kidney disease associated with monoclonal IgG2 is extremely rare. This multi-institutional retrospective study includes 10 cases of IgG2-associated kidney disease, encompassing various pathological diagnoses.
Case Description
This cohort includes 4 male and 6 female patients. Medium age was 54.5yo(range:17–74). 2 pts had histories of chronic lymphocytic leukemia. Monoclonal protein was detected in 5 pts (SPEP and/or UPEP). 8 pts showed κ restriction; 2 showed λ restriction by kidney biopsy.
1 patient was diagnosed with IgG2-κ renal amyloidosis.
1 patient demonstrated a mild increase in mesangial cellularity with early nodule formation. IF: linear/ribbon-like staining for IgG and κ LC along GBM and TBM. Although no powdery deposits by EM, these findings are suggestive of early κ light chain deposition disease.
4 pts showed glomerular monoclonal paraprotein deposition with fibrillary or curvillinear substructures by EM. These pts were diagnosed with type 1 cryoglobulinemic glomerulonephritis or monoclonal immunotactoid glomerulopathy. 3 pts showed IgG2-κ deposits; 1 showed IgG2-λ restriction. 1 patient also showed IgG2-κ pseudothrombi within the lumina of small arteries, accompanied by focal vasculitis.
1 with a history of CLL showed diffuse proliferative glomerular nephritis with oligoclonal (IgG2/κ dominant) deposits, with lesser IgM and negligible λ. With coarse fibrillary substructure by electron microscopy, this patient was diagnosed with type II cryoglobulinemia.
Two patients were diagnosed with proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID). One showed focal proliferative pattern of glomerular injury, with IgG2-κ deposition. The other showed membranoproliferative pattern of glomerular injury, with IgG2-λ deposition. No substructures were identified on EM.
1 showed mesangial proliferative glomerulonephritis with IgG1 (1+), lesser IgG2 (trace-1+), and λ restriction. DDx of cryoglobulinemia and SLE were rendered.
Discussion
Monoclonal IgG2associated kidney diseases exhibit a broad range of pathological manifestations.