Overlapping IgA and membranous nephropathy

Area of Science:

• Nephrology
• Immunopathology
• Glomerular Diseases

Background:

• IgA nephropathy (IgAN) and membranous nephropathy (MN) are distinct glomerular diseases.
• Overlapping features of IgAN and MN are rarely reported, with only four cases previously documented in Japan.

Observation:

• This report details three patients from the United States exhibiting concurrent IgA nephropathy and membranous nephropathy.
• All patients presented with hematuria and nephrotic-range proteinuria.
• Renal biopsies showed characteristic glomerular lesions, including mesangial and subepithelial electron-dense deposits, with specific IgA and IgG immunostaining patterns.

Findings:

• Biopsies revealed focal proliferative glomerular lesions.
• Distinct immunofluorescence findings included intense mesangial IgA staining and extensive granular capillary wall IgG staining.
• Electron microscopy confirmed large mesangial and numerous subepithelial electron-dense deposits.

Implications:

• The findings suggest a possible shared or coexisting pathogenic pathway for IgAN and MN in some individuals.
• Further research is warranted to elucidate the underlying mechanisms of these overlapping glomerular diseases.
• Understanding these overlaps may lead to improved diagnostic and therapeutic strategies for patients with complex kidney conditions.