Which MPGN type is defined by subendothelial immune complex deposits with granular IF and is associated with HBV/HCV?

Which MPGN type is defined by subendothelial immune complex deposits with granular IF and is associated with HBV/HCV?

• A. Type 3
• B. Type 4
• C. Type 2
• D. Type 1

Answer: (D)

In membranoproliferative GN, the pattern and location of immune deposits drive the classification. Subendothelial immune complex deposits that produce a granular immunofluorescence signal indicate an immune-complex–mediated process. When these deposits sit in the subendothelial space and IgG with C3 are detected on IF, this is the hallmark of the first MPGN type. The association with hepatitis B or C fits the mechanism, since chronic infections promote circulating immune complexes that lodge in the glomeruli. In contrast, a dense, intramembranous C3-dominant pattern characterizes the second type, with minimal immunoglobulin staining, and it’s not typically linked to HBV/HCV. The third type shows both subepithelial and subendothelial deposits and can have variable immunofluorescence. So the described subendothelial, granular immune deposits with HBV/HCV association align best with the first type.

In membranoproliferative GN, the pattern and location of immune deposits drive the classification. Subendothelial immune complex deposits that produce a granular immunofluorescence signal indicate an immune-complex–mediated process. When these deposits sit in the subendothelial space and IgG with C3 are detected on IF, this is the hallmark of the first MPGN type. The association with hepatitis B or C fits the mechanism, since chronic infections promote circulating immune complexes that lodge in the glomeruli.

In contrast, a dense, intramembranous C3-dominant pattern characterizes the second type, with minimal immunoglobulin staining, and it’s not typically linked to HBV/HCV. The third type shows both subepithelial and subendothelial deposits and can have variable immunofluorescence. So the described subendothelial, granular immune deposits with HBV/HCV association align best with the first type.