C4d immunohistochemical staining is a sensitive method to confirm immunoreactant deposition in formalin-fixed
J F Val-Bernal1, M F Garijo, D Val
1Department of Anatomical Pathology, Marqués de Valdecilla University Hospital, University of Cantabria, Santander, Spain.
Abstract:
Although the diagnosis of membranous glomerulonephritis (MGN) may be suspected on routine histology of formalin-fixed paraffin-embedded tissue, fresh-frozen tissue must be used to show the immunologic nature of the process by direct immunofluorescence (IF). The efficiency of IF or immunoperoxidase (IP) detection of IgG and C3 using paraffin sections is controversial. This study was designed to evaluate whether glomerular C4d deposition using an IP method in formalin-fixed paraffin-embedded tissue may be a useful marker for MGN. We showed characteristic glomerular, granular basement membrane deposition of C4d in 31 (100%) cases of idiopathic MGN and in 5 cases (100%) of pure class V membranous lupus nephritis, in which we had a positive diagnosis of the lesions for conventional IF study. Control cases were negative. Nineteen cases of different glomerulopathies, including IgA nephropathy, primary type I membranoproliferative glomerulonephritis, focal segmental glomerulosclerosis and minimal change disease showed diverse reproducible patterns of C4d deposition, without intrinsic background. Our results indicate that staining of formalin-fixed paraffin-embedded tissue for C4d can be used for confirmation of granular basement membrane immunoreactant deposition in cases of MGN. This proved to be a reliable method that could potentially obviate the need for rebiopsy in cases with absence of glomeruli in renal frozen sections or when other adjunct IF or IP methods on paraffin sections are negative. C4d immunostaining, using an IP method, deserves a place as an adjunct method in the biopsy diagnosis of MGN.
Insights
Complement C4d deposition in formalin-fixed paraffin-embedded tissue is a reliable marker for diagnosing membranous glomerulonephritis (MGN). This immunoperoxidase staining method can confirm immune deposits, potentially avoiding repeat biopsies.
Area of Science:
- Nephrology
- Immunopathology
- Diagnostic Pathology
Background:
- Diagnosis of membranous glomerulonephritis (MGN) typically requires fresh-frozen tissue for immunofluorescence (IF).
- The utility of immunoperoxidase (IP) staining for IgG and C3 on paraffin sections in MGN diagnosis remains debated.
- Formalin-fixed paraffin-embedded (FFPE) tissue is more readily available and easier to handle than fresh-frozen tissue.
Purpose of the Study:
- To evaluate C4d deposition using IP staining on FFPE tissue as a diagnostic marker for MGN.
- To determine if C4d staining can reliably confirm granular basement membrane immunoreactant deposition in MGN.
- To assess the potential of C4d staining to reduce the need for rebiopsies in specific clinical scenarios.
Main Methods:
- Immunoperoxidase (IP) staining for C4d was performed on FFPE renal biopsy tissues.
- Analyzed 31 cases of idiopathic MGN and 5 cases of class V lupus nephritis with confirmed MGN by conventional IF.
- Included 19 control cases of various glomerulopathies and negative control cases.
Main Results:
- Characteristic glomerular, granular basement membrane C4d deposition was observed in 100% of idiopathic MGN and lupus nephritis cases.
- Control cases showed diverse, reproducible C4d deposition patterns without intrinsic background.
- The method demonstrated high sensitivity and specificity for detecting immune deposits in MGN.
Conclusions:
- C4d immunostaining on FFPE tissue is a reliable adjunct method for confirming granular basement membrane immunoreactant deposition in MGN.
- This technique can potentially obviate the need for rebiopsy when fresh-frozen tissue is unavailable or other methods are inconclusive.
- C4d staining offers a valuable tool for the biopsy diagnosis of MGN, enhancing diagnostic efficiency.
