What are the Kidney biopsy findings of Membranous Nephropathy?
The diagnosis of Membranous Nephropathy is based on the following findings:
- • Thickened GBM, often showing pinholes or spikes on silver and periodic acid–Schiff stains, and occasionally subepithelial fuchsinophilic deposits on trichrome stains
- • Immunofluorescence microscopy showing granular Ig (usually IgG and C3) along the capillary walls
- • Subepithelial deposits on EM.
However, in the early stages of the disease, light microscopy may be completely normal. Based on the location of the deposits on EM, MN has been divided into four stages:
- • Stage I, sparse small deposits without thickening of the GBM
- • Stage II, more extensive subepithelial deposits with formation of basement membrane spikes between the deposits and thickening of the GBM
- • Stage III, combination of stage II along with deposits completely surrounded by basement membrane (intramembranous deposits)
- • Stage IV, incorporation of deposits in the GBM and irregular thickening of the GBM
- • However, these stages have no correlation with clinical outcome.
