IgGdeposities

IgGdeposities refers to the presence of immunoglobulin G deposits in tissues, typically detected by immunofluorescence or immunohistochemistry on biopsy. These deposits arise from immune complexes formed in situ or from autoantibodies binding to tissue antigens. They are most commonly observed in the kidneys, but can also be found in the skin, blood vessels, and other organs.

Patterns of deposition include linear and granular. Linear IgG along the glomerular basement membrane is characteristic of anti-GBM disease. Granular IgG along basement membranes or within the mesangium is typical of immune complex–mediated diseases such as membranous nephropathy and lupus nephritis. The distribution and pattern of IgG, as well as the IgG subclass composition (notably IgG4 in some conditions), can aid diagnosis. IgG4-related disease is a distinct fibroinflammatory condition marked by infiltration of IgG4-positive plasma cells and can involve multiple organs.

Clinical relevance: the finding of IgG deposition is a marker of immune-mediated tissue injury and helps classify renal and vasculitic diseases, as well as other inflammatory conditions. It must be interpreted in the context of clinical presentation, serologic studies, and other histologic findings.

Management: treatment targets the underlying condition and may include immunosuppressive therapy, supportive measures for kidney disease, plasmapheresis in selected anti-GBM cases, or therapies specific to IgG4-related disease. Understanding the pattern and context of IgG deposition guides prognosis and therapeutic decisions.