Aim
We designed a new diagnostic method by immunohistochemistry (IHC) for IgG4 on paraffin sections instead of fresh frozen tissue and evaluated sensitivity, specificity, and positive and negative predictive values of this method. Materials and
Conclusion
Immunohistochemical labeling for IgG4 on paraffin-embedded tissue provides a sensitive and specific test for diagnosing pemphigus in a situation when fresh frozen tissue is unavailable.
Methods
We searched our pathologic archive of pemphigus of 35 patients, including 29 cases of pemphigus vulgaris (PV) and 6 patients with pemphigus foliaceus (PF). In all cases, the diagnosis was confirmed by indirect immunofluorescence studies. Thirty-five specimens served as controls, including 31 specimens of safe margins of basal cell carcinoma and 4 specimens of normal skin. Sections with condensed and continuous immunoreactivity localized to the intercellular junctions of keratinocytes were considered as positive.
Results
Sensitivity of IgG4 was estimated to be 72.4% in PV group and 83.3% in PF group. The overall sensitivity and specificity of IgG4 IHC for diagnosis of pemphigus were 74.2% and 82.8%, respectively, in PV and PF groups. Furthermore, positive predictive value and negative predictive value were 81.2% and 76.3%, respectively.