Application of C4d Immunohistochemistry on Routinely Processed Tissue Sections for the Diagnosis of Autoimmune Bullous Dermatoses

Abstract

The diagnosis of autoimmune bullous dermatoses relies greatly on direct immunofluorescence (DIF) examination performed on frozen tissue sections, showing deposits of immunoglobulins and/or C3 on specific cutaneous structures. However, frozen material is not always available for DIF; therefore, alternative techniques are needed in the diagnostic procedure. We therefore tested the usefulness of C4d immunohistochemistry on formalin-fixed, paraffin-embedded tissue sections for the diagnosis of bullous pemphigoid (BP) and pemphigus (P). A retrospective immunohistochemical study was performed on biopsies of BP (n: 29) and P (n: 22, including 19 Pemphigus vulgaris and 3 paraneoplastic), submitted for routine histological examination and compared with DIF on the corresponding frozen sections. Twenty-five BP biopsies (86.2%) showed C4d deposits seen as a linear labeling along the dermal-epidermal junction and on the membrane of basal keratinocytes. Seventeen P biopsies (77.2%) showed C4d deposits in a classical "intercellular" pattern, predominating on the lower epidermal layers. The sensitivity, specificity, positive predictive value, and negative predictive value reached 86%, 98%, 96%, and 92% in BP, respectively and 77%, 98%, 94%, and 92% in P, respectively. Furthermore, in the cases where serological tests were available, the sensitivity of C4d detection was higher than that of enzyme-linked immunosorbent assay/indirect immunofluorescence in both BP (87% vs. 67%) and P (82% vs. 54.5%). We conclude that DIF on frozen sections still remains the gold standard for the immunopathological diagnosis of BP and P; however, in the absence of frozen material, C4d immunohistochemistry performed on routinely processed biopsy material can be of considerable help in confirming the diagnosis.

Diagnostic value of immunohistochemistry on formalin-fixed, paraffin-embedded skin biopsy specimens for bullous pemphigoid

“…Another recent IHC study similarly reports the detection of diagnostic linear deposits of C4d in 86% of 29 skin biopsies obtained from patients with BP. Again, the majority of the included cases (> 70%) histologically showed subepidermal blister formation …”

Diagnosis of autoimmune bullous diseases

“…Various studies have evaluated the visualization of immunoglobulins and C3d/C4d in paraffin‐embedded lesional biopsies. The results to date have shown significantly lower sensitivity and specificity than for direct IF microscopy of perilesional biopsies .…”

Diagnostik blasenbildender Autoimmundermatosen

“…In verschiedenen Studien wurde die Visualisierung von Immunglobulinen und C3d/C4d in läsionalen, in Paraffin eingebetteten Biopsien untersucht. Die bisherigen Resultate ergaben eine deutlich geringere Sensitivität und Spezifität als die direkte IF‐Mikroskopie periläsionaler Biopsien .…”