What are the typical biopsy findings in Immunoglobulin A Nephropathy?
On light microscopy (LM), mesangial cellular proliferation and matrix expansion are the classic findings.
In cases with rapid deterioration in kidney function, diffuse proliferation of both the mesangial and endocapillary cells can be appreciated, in association with segmental necrosis and crescents.
Nonspecific pathologic features associated with advanced glomerular diseases in general can be seen in IgAN, including glomerulosclerosis, tubular atrophy, and interstitial fibrosis.
On immunofluorescence (IF), the defining feature of IgAN is the presence of prominent IgA deposits within the mesangium in a dominant or codominant intensity with IgG and more rarely IgM.
On electron microscopy (EM), electron-dense mesangial deposits are the typical finding.
Paramesangial and subendothelial extension of the deposits may be present but are less common.
