Background: In many countries and laboratories, techniques such as direct immunofluorescence (DIF) are not available for the diagnosis of skin diseases. Thus, these laboratories are limited in the full diagnoses of autoimmune skin diseases, vasculitis, and rheumatologic diseases. In our experience with these diseases and the patient's skin biopsies, we have noted a positive correlation between periodic acid-Schiff (PAS) staining and immunofluorescence patterns; however, these were just empiric observations. In the current study, we aim to confirm these observations, given the concept that the majority of autoantibodies are glycoproteins and should thus be recognized by PAS staining.
Aims: To compare direct immunofluorescent and PAS staining, in multiple autoimmune diseases that are known to exhibit specific direct immunofluorescent patterns.
Materials and methods: We studied multiple autoimmune skin diseases: Five cases of bullous pemphigoid, five cases of pemphigus vulgaris, ten cases of cutaneous lupus, ten cases of autoimmune vasculitis, ten cases of lichen planus (LP), and five cases of cutaneous drug reactions (including one case of erythema multiforme). In addition, we utilized 45 normal skin control specimens from plastic surgery reductions.
Results: We found a 98% positive correlation between DIF and PAS staining patterns over all the disease samples.
Conclusion: We recommend that laboratories without access to DIF always perform PAS staining in addition to hematoxylin and eosin (H&E) staining, for a review of the reactivity pattern.
Keywords: Autoimmune vasculitis; bullous pemphigoid; cutaneous drug reactions; direct immunofluorescence (DIF); lupus erythematosus (LE); pemphigus vulgaris; periodic acid-Schiff (PAS); periodic acid-Schiff staining; skin autoimmune blistering diseases.