case_images: PMC11099222_01
case_images: Diagnostic evaluation and clinical course of Case 1. (A) Scattered light red rashes on both lower extremities. (B) Immunofixation electrophoresis. A monoclonal IgM kappa and polyclonal IgG. (C) Light microscopy. Membranoproliferative glomerulonephritis pattern. (D) Clinical course in case 1 with associated pertinent laboratory values from time of diagnosis to last follow-up.
case_images: fimmu-15-1390958-g001.jpg
case_images: PMC11099222_01_fimmu-15-1390958-g001.jpg
case_images: f1
case_images: His rash extended to involve the knee joints (as shown in  Figure 1A ), with increased tingling sensation, leading to unstable walking. Cryoglobulin testing was positive, and immunofixation of cryoglobulin revealed a monoclonal IgM kappa and polyclonal IgG, characterized of type II cryoglobulinemia (as shown in  Figure 1B ). Renal biopsy revealed MPGN with suspected cryoglobulinemic renal damage (as shown in  Figure 1C ). We have summarized the clinical course in  Figure 1D .
case_images: PMC11099222_02
case_images: Diagnostic evaluation and clinical course of Case 2. (A) Light microscopy. Membranoproliferative glomerulonephritis pattern. (B) Electron microscopy. electron-dense deposits in the mesangial area. (C) Immunofixation electrophoresis. A monoclonal IgM kappa and polyclonal IgG. (D) Clinical course in case 2 with associated skin manifestations from time of diagnosis to last follow-up.
case_images: fimmu-15-1390958-g002.jpg
case_images: PMC11099222_02_fimmu-15-1390958-g002.jpg
case_images: f2
case_images: The cryoglobulin tested positive, and immunofixation of the cryoglobulin revealed a monoclonal IgM kappa and polyclonal IgG, consistent with type II mixed cryoglobulinemic vasculitis (as shown in  Figure 2C ). Renal biopsy revealed MPGN with hemosiderin deposits in the mesangial area and thrombus-like material deposition in a few glomerular capillary lumens, consistent with cryoglobulin-related renal damage (as shown in  Figure 2A ). Electron microscopy showed electron-dense deposits in the mesangial area (as shown in  Figure 2B ). We have summarized the clinical course in  Figure 2D .