Cryoglobulinemic Glomerulopathy Complicating Helicobacter pylori–Associated Gastric Mucosa–Associated Lymphoid Tissue Lymphoma

Immunofixation electrophoresis of cryoprecipitate. The cryoprecipitate was resuspended in normal saline, processed by using agarose electrophoresis, and stained by using standard immunofixation techniques for immunoglobulin G (IgG), IgA, IgM, Igκ, and Igλ, as indicated. Single bands in the IgM and Igκ lanes reflect the presence of monoclonal IgMκ, and the smear in the IgG lane is indicative of the presence of polyclonal IgG. The first lane contains serum as a standard.

Light microscopic evaluation of the gastric mucosal biopsy specimen. (A) Hematoxylin and eosin–stained section of gastric mucosal biopsy shows dense lymphoid infiltrate; (B) immunohistochemical stain for Helicobacter pylori shows organisms within and on the surface epithelium; (C) immunohistochemical stain shows CD20 expression in the lymphoid cells (brown); and in situ hybridization shows (D) immunoglobulin κ (Igκ) expression within most of the infiltrating lymphocytes (black) and (E) few scattered lymphoid cells expressing Igλ (black).

Light microscopy of the renal biopsy specimen shows membranoproliferative changes. (A) Hematoxylin and eosin, (B) periodic acid–Schiff, and (C) Jones silver-stained images of glomerulus show endocapillary proliferation with lobular accentuation, capillary “thrombi” consisting of cryoglobulins (arrows), and thickened capillary loops with double contours (arrowheads). The bar represents 25 μm.

Renal biopsy specimen using immunofluorescence and electron microscopy. Immunofluorescence microscopy shows intense segmental deposits of (A) immunoglobulin G (IgG) and (B) IgM, corresponding to the large glomerular intracapillary cryoglobulins (arrows) and granular subendothelial deposition of immune complexes within capillary loops (arrowheads). The bar represents 50 μm. (C, D) Electron microscopy shows subendothelial deposit (arrows) and glomerular basement membrane reduplication (arrowheads). (D) The large deposit shows a vaguely organized tubular substructure (original magnification: [C] ×7,100; [D] ×22,000).