Objectives: We describe a 62-year-old woman with a 15-year history of a plasma cell dyscrasia (monoclonal IgGκ), manifested by type I cryoglobulinemia and dermal vasculitis.
Methods: In addition to the clinical examinations, light microscopy with immunohistochemistry, sequential multicolor immunohistochemistry, and electron microscopy were used to characterize the crystalline deposits.
Results: At initial presentation and for a later flare, she was treated with cyclophosphamide and prednisolone with good clinical response. She had renal function decline, microscopic hematuria, and proteinuria. A renal biopsy specimen revealed the presence of glomerular macrophages and duplication of the capillary walls with cellular interposition. Glomerular cells contained abundant needle-shaped eosinophilic crystalline inclusions positive for κ light chain. Electron microscopy confirmed the presence of intracytoplasmatic crystalline structures in endothelial cells, podocytes, and macrophages but not in the tubular epithelium. Rituximab treatment was started. At follow-up (now up to 6 months), renal function remained stable.
Conclusions: This patient displays a unique renal manifestation of type I cryoglobulinemia related to a plasma cell dyscrasia.
Keywords: Cryoglobulinemia; Crystalloid nephropathy; Crystals; Glomerulopathy.
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