A unique case of γ-heavy chain deposition disease characterized by concomitant deposition of γ2 and γ4 subclasses

Heavy chain deposition disease (HCDD) is a rare entity. γ-HCDD is the predominant subtype and is characterized by glomerular and tubular deposition of a single γ-heavy chain subclass. To our knowledge, γ-HCDD with simultaneous deposition of two subclasses has not yet been described. A 39-year-old woman presented with hypertension, nephrotic syndrome, anemia, microscopic hematuria and progressive renal dysfunction. A light microscopic examination of renal biopsy specimens showed nodular glomerulosclerosis. Electron microscopy revealed electron-dense deposits along the glomerular and tubular basement membranes. Immunofluorescence microscopy showed positive glomerular and tubular staining for immunoglobulin G (IgG) and negative staining for κ and λ light chains. An analysis of the IgG subclass showed positive staining for both IgG2 and IgG4. We herein describe a unique case of γ-HCDD with concurrent deposition of two subclasses, presenting a new subtype to the disease spectrum.