A case of podocytic infolding glomerulopathy with multiple myeloma
Makoto Harada, Yuji Kamijo1, Takashi Ehara
1Department of Nephrology, Shinshu University School of Medicine, 3-1-1, Asahi, Matsumoto, Nagano 390-8621, Japan. yujibeat@shinshu-u.ac.jp.
Background:
Podocytic infolding glomerulopathy (PIG) is a recently described condition causing rare pathological changes to the glomeruli, and has attracted considerable attention. PIG is characterized by specific changes to the thickened glomerular basement membrane (GBM), including microspheres, microtubular structures, and podocytic infolding. Only a small number of cases of PIG have been reported. The clinical features and pathogenesis of this condition are still unclear. To elucidate the characteristics of this glomerulopathy, it is necessary to accumulate information from reported cases. We present here the first reported case of PIG with multiple myeloma.
Case Presentation:
A 79-year-old Japanese man was admitted to his local hospital with proteinuria, hypergammaglobulinemia, hypoalbuminemia, and kidney dysfunction. Laboratory tests revealed monoclonal IgG(λ) M proteins in the serum and Bence-Jones proteins in the urine. Bone marrow aspiration showed monoclonal plasma cell proliferation, indicating a diagnosis of multiple myeloma. Renal biopsy was performed to determine the cause of the proteinuria and kidney dysfunction. Histological examination of the biopsy specimen showed glomeruli with an irregularly thickened GBM and bubble-like structures in the capillary walls. Immunofluorescence staining did not show glomerular deposition of immunoglobulins, light chains, or complement components. Congo red staining did not show amyloid deposition. Electron microscopy showed an irregularly thickened GBM with unusual structures in the glomerular capillary walls including podocytic infolding and microspheres, suggesting PIG. There were no electron-dense deposits in the GBM, while various findings indicating podocyte injury were detected.
Conclusion:
We present here the first reported case of PIG in a patient with multiple myeloma. The mechanisms underlying the development of PIG in multiple myeloma are unknown, but may be associated with podocyte injury.
Insights
Podocytic infolding glomerulopathy (PIG) is a rare kidney disease. This report details the first case of PIG in a patient with multiple myeloma, suggesting a link to podocyte injury.
Area of Science:
- Nephrology
- Pathology
- Oncology
Background:
- Podocytic infolding glomerulopathy (PIG) is a rare glomerular disease characterized by thickened glomerular basement membrane (GBM) with specific ultrastructural changes.
- PIG has attracted attention due to its rarity and unclear pathogenesis, necessitating case accumulation for better understanding.
- This study presents the first reported case of PIG co-occurring with multiple myeloma.
Observation:
- A 79-year-old male presented with proteinuria, kidney dysfunction, and laboratory findings indicative of multiple myeloma.
- Renal biopsy revealed characteristic GBM thickening with microspheres and podocyte infolding, consistent with PIG, but without immunoglobulin or amyloid deposition.
Findings:
- The case demonstrates the first co-occurrence of PIG and multiple myeloma.
- Electron microscopy confirmed GBM abnormalities and podocyte injury without electron-dense deposits.
Implications:
- This case expands the understanding of PIG by associating it with multiple myeloma.
- Further research is needed to elucidate the mechanisms linking multiple myeloma and podocyte injury in PIG.
