Paraffin-based immunohistochemistry in the evaluation of glomerular diseases in renal biopsies

Objective: To determine sensitivity and specificity of paraffin-based immunohistochemistry in the evaluation of glomerular diseases in renal biopsies using immunofluorescence as gold standard. Study Design: Cross-sectional analytical study. Place and Duration of Study: Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, from August 2008 to August 2009. Methodology: Seventy renal biopsy specimens fulfilling the inclusion criteria for light microscopy and immuno-fluorescence during the study period were evaluated. Antibodies to immunoglobulins (IgG, IgA, and IgM) and components of complement system (C3) were applied on 70 formalin-fixed paraffin-embedded renal biopsy specimens previously classified by means of light microscopy and immunofluorescence (IF). Staining for these antibodies was recorded as positive and negative for immunohistochemistry (IHC) and IF in paired proportions presuming IF as gold standard test. The sensitivity, specificity, positive predictive value and negative predictive value of individual antibody were calculated. Results: Of 70 patients, mean age was 33 +- 18 years ranging from 2 to 80 years. Forty five (64%) were males and 25 (36%) were females. The sensitivity, specificity and predictive values of individual antibodies to IgG, IgA, IgM and C3 were very low and generally in the range of 40 - 60%. Conclusion: The sensitivity, specificity and predictive values of immunohistochemistry on formalin-fixed paraffin-embedded renal biopsy specimens were very low and therefore, not suitable for evaluation of renal biopsies in current circumstances. (author)