From the Departments of Dermatopathology (N Wu, Cai, F Wu, Liang, S Liu, Y Liu) and Central Laboratory (Zhang), Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China.
Arch Pathol Lab Med. 2024 Sep 1;148(9):1022-1027. doi: 10.5858/arpa.2023-0274-OA.
CONTEXT.—: Pemphigus is an autoimmune blister disease that causes blisters on the skin and mucosal surfaces. Direct immunofluorescence (DIF) testing is critical for the clinical diagnosis of pemphigus. However, it is limited to fresh tissue specimens and fluorescence microscopy.
OBJECTIVE.—: To assess the value of C3d immunohistochemistry (IHC) on paraffin-embedded skin tissue for the diagnosis of pemphigus by comparing C3d-IHC results to DIF and enzyme-linked immunosorbent assay testing in pemphigus and other blister-related skin diseases.
DESIGN.—: C3d-IHC assays were retrospectively performed on paraffin-embedded skin tissue sections from 115 patients (63 with pemphigus and 52 controls). Both the case group and the control group underwent the same protocol, and cases with C3d position in the peripheral spinous layer were considered as positive samples.
RESULTS.—: C3d-IHC and DIF testing had similar performance for pemphigus diagnosis, with a sensitivity of 71.0% (95% CI, 51.8%-85.1%) and 77.4% (95% CI, 58.5%-89.7%), specificity of 96.4% (95% CI, 79.8%-99.8%) and 100% (95% CI, 85.0%-100%), positive predictive value of 95.7% (95% CI, 76.0%-99.8%) and 100% (95% CI, 82.8%-100%), and a negative predictive value of 75.0% (95% CI, 57.5%-87.3%) and 80.0% (95% CI, 62.5%-90.9%), respectively.
CONCLUSIONS.—: Our study indicated that C3d-IHC results for paraffin-fixed tissues were not significantly different from DIF results for the diagnosis of pemphigus. The C3d-IHC assay has the potential for routine diagnosis of pemphigus, especially in the absence of fresh-frozen tissue.
天疱疮是一种自身免疫性水疱病，可导致皮肤和黏膜表面出现水疱。直接免疫荧光（DIF）检测对天疱疮的临床诊断至关重要。然而，它仅限于新鲜组织标本和荧光显微镜检查。
通过比较天疱疮和其他疱性皮肤病的 DIF 和酶联免疫吸附试验（ELISA）检测，评估 C3d 免疫组织化学（IHC）在石蜡包埋皮肤组织中的诊断价值。
对 115 例患者（63 例天疱疮和 52 例对照）的石蜡包埋皮肤组织切片进行了 C3d-IHC 检测。病例组和对照组均采用相同的方案，C3d 在周围棘状层中的位置被认为是阳性样本。
C3d-IHC 和 DIF 检测对天疱疮的诊断具有相似的性能，敏感性分别为 71.0%（95%CI，51.8%-85.1%）和 77.4%（95%CI，58.5%-89.7%），特异性分别为 96.4%（95%CI，79.8%-99.8%）和 100%（95%CI，85.0%-100%），阳性预测值分别为 95.7%（95%CI，76.0%-99.8%）和 100%（95%CI，82.8%-100%），阴性预测值分别为 75.0%（95%CI，57.5%-87.3%）和 80.0%（95%CI，62.5%-90.9%）。
本研究表明，石蜡固定组织的 C3d-IHC 结果与 DIF 结果在诊断天疱疮方面无显著差异。C3d-IHC 检测法有可能成为天疱疮的常规诊断方法，尤其是在缺乏新鲜冷冻组织的情况下。
