Role of kidney biopsy to detect secondary causes of Membranous Nephropathy
Can kidney biopsy findings be helpful in identifying secondary causes of Membranous Nephropathy?
Although it is often difficult to determine whether the Membranous Nephropathy is primary or secondary based on kidney pathology, certain features are helpful in identifying a primary versus secondary cause.
Commercial tests are available that allow for staining of kidney tissue for anti-PLA 2 R and THSD-7A, which aids in identifying primary forms of MN. Features in favor of a secondary cause, in particular an autoimmune disease, include the following:
• Proliferative features (mesangial or endocapillary)
• Full-house pattern of Ig staining including staining for C1q on immunofluorescence microscopy
• Glomerular deposits predominantly containing Ig other than IgG4 on immunofluorescence microscopy
• Electron-dense deposits in the subendothelial location of the capillary wall and mesangium or along the tubular basement membrane and vessel walls
• Endothelial tubuloreticular inclusions on EM (EM showing only few superficial scattered subepithelial deposits may suggest a drug-associated secondary Membranous Nephropathy)