Proliferative glomerulonephritis with monoclonal IgM-κ deposits in chronic lymphocytic leukemia/small lymphocytic leukemia: case report and review of the literature

Abstract

A 48-year-old man with chronic lymphocytic leukemia presented with nephrotic syndrome, hematuria, and mild deterioration of renal function. Further analysis using serum immunofixation electrophoresis detected monoclonal immunoglobulin (Ig) M-κ and IgG-κ M-protein. Testing for cryoglobulin in serum was negative. Light microscopy of a renal biopsy specimen showed membranoproliferative glomerulonephritis features with marked mononuclear cell infiltration in the interstitium. On immunofluorescence study, the deposition of IgM heavy chain was predominantly observed with the same distribution of κ light chain, whereas no λ light chain was found. Electron microscopy revealed fine granular deposits in the mesangial, subendothelial, and subepithelial areas, mimicking those observed in the immune complex-mediated glomerulonephritis. These pathological findings were consistent with recently described cases of proliferative glomerulonephritis with monoclonal IgG deposits. Thus, monoclonal IgM deposition can also cause proliferative glomerulonephritis.

Keywords: Lymphoproliferative disorder; Membranoproliferative glomerulonephritis; Monoclonal IgM-κ; Nephrotic syndrome.

Fig. 1

a Proliferation of mesangial and endocapillary cells with thickening of the basement membrane and double contour formation are observed [periodic acid-Schiff (PAS) stain, original magnification ×400]. b Immunoglobulin (Ig) M heavy chain is strongly positive. c IgG heavy chain is negative. d Stain of κ light chain is positive. e λ light chain is entirely negative [immunofluorescence (IF) study, original magnification ×400, respectively]

Fig. 2

a Electron microscopy shows finely granular electron-dense deposits in the paramesangial and subendothelial areas resembling immunocomplex glomerulonephritis (original magnification ×3000). b Subepithelial deposits (arrows) are also observed (original magnification ×5000)

Fig. 3

a Specific staining for CD20 is positive (original magnification ×200). b Fluorescence in situ hybridization analysis of paraffin-embedded sections (PS-FISH) demonstrates split signal for Ig heavy chain (IgH). The arrows show distinct red (centromere site) and green (telomere site) split signals in nuclei, suggesting IgH gene rearrangement