The specificity and sensitivity of Nikolskiy sign in the diagnosis of pemphigus

BackgroundThe Nikolskiy sign is a well-known mechanical symptom that can be helpful in the diagnosis of pemphigus. The reports about associations with other than pemphigus cause confusion concerning the diagnostic importance of the Nikolskiy sign in pemphigus.ObjectiveOur purpose was to examine the significance and usefulness of the Nikolskiy sign on the clinical diagnosis of pemphigus by determination of its sensitivity and specificity.MethodsPresence of the Nikolskiy sign with the modifications of “direct” and “marginal” on 123 consecutive patients with various cutaneous diseases presenting as intact blisters and/or erosions was sought.ResultsA positive Nikolskiy sign was demonstrated in 24 (19.5%) of the 123 patients. Of the positive 24 patients, 18 had pemphigus, 4 had bullous pemphigoid, 1 had linear IgA dermatosis, and 1 had staphylococcal scalded skin syndrome. The sensitivity of “direct” Nikolskiy sign (38%) was less than that of the “marginal” form (69%), but the specificity of “direct” Nikolskiy sign (100%) was higher than that of the “marginal” form (94%) in the diagnosis of pemphigus.LimitationsThis study was primarily concerned with the diagnostic importance of the Nikolskiy sign in pemphigus. We did not focus on its prognostic value in pemphigus. The small size of the group of patients with pemphigus, which is related to low annual incidence of pemphigus in our region, is another limitation of this study.ConclusionsThe Nikolskiy sign offers a moderately sensitive but highly specific tool for the diagnosis of pemphigus.