Abstract: FR-PO0939
A Case of Nephrotic Syndrome with IgM Monoclonal Gammopathy: Differentiating Primary FSGS from Monoclonal Gammopathy of Renal Significance
Session Information
- Glomerular Case Reports: Lupus, FSGS, Complement, and More
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Kato, Mariko, Resilience Healthcare - Weiss Memorial Hospital LLC, Chicago, Illinois, United States
- Boumaraf, Imane, Resilience Healthcare - Weiss Memorial Hospital LLC, Chicago, Illinois, United States
- Henriksen, Kammi J., The University of Chicago Medicine, Chicago, Illinois, United States
- Chan, Emily Shu-Yen, Resilience Healthcare - Weiss Memorial Hospital LLC, Chicago, Illinois, United States
- Buyukcelebi, Kadir, Resilience Healthcare - Weiss Memorial Hospital LLC, Chicago, Illinois, United States
- Ali, Mustafa, Resilience Healthcare - Weiss Memorial Hospital LLC, Chicago, Illinois, United States
Introduction
When evaluating patients with mild monoclonal gammopathy and kidney disease, it remains challenging to differentiate monoclonal gammopathy of renal significance (MGRS) from the incidental coexistence of monoclonal gammopathy of undetermined significance and kidney disease.
Case Description
A 73-year-old male with a history of ischemic heart disease and stage 2 chronic kidney disease presented to his primary care physician with anasarca and dyspnea for 1 week. Laboratory tests revealed acute kidney injury with a serum creatinine of 4.16 mg/dL (baseline 1.3 mg/dL 3 months earlier), hypoalbuminemia, and a urine protein-to-creatinine ratio of 6.48 g/g creatinine. Serum IgM was elevated at 18.91 g/L. Bone marrow biopsy was normocellular. Kidney biopsy demonstrated focal segmental glomerulosclerosis (FSGS) with ultrastructural evidence of severe podocyte injury. Immunofluorescence demonstrated only faint IgM trapping in glomeruli which was considered nonspecific. After discussion among nephrology, pathology, and hematology teams, the IgM monoclonal gammopathy was deemed unrelated to the FSGS. In addition to guideline-directed therapy for proteinuria, glucocorticoids are planned for primary FSGS.
Discussion
Although FSGS has been reported as one of the manifestations of MGRS, our case did not show immunoglobulin deposition on kidney biopsy, and the diagnostic criteria for MGRS were not met. Since both primary FSGS and MGRS can potentially progress to end-stage renal disease and require different treatments, careful evaluation through a multidisciplinary team is essential.
Electron microscopy showed diffuse effacement of the podocyte foot processes with cytoplasmic swelling and microvillous transformation. There were no immune-type electron-dense deposits or fibrils.