Pemphigus vulgaris (PV) is an autoimmune mucocutaneous blistering disease caused by anti-desmoglein (Dsg) autoantibodies. Alopecia has been reported as a manifestation of PV; however, its incidence is quite low. In this study, we attempted to delineate the characteristics and clinical significance of this rare symptom, based on the clinicopathological observations of a 31-year-old Japanese male alopecic PV case we treated. Notably, the hair loss in this PV case was not characterized by alopecic patches, but rather by the finding that hair shafts with visibly intact outer root sheath (ORS) were easily collected using a gentle hair pull test. Direct immunofluorescence detected intracellular IgG deposition on ORS keratinocytes. In addition, acantholysis was observed within ORS where Dsg1 and 3 were weakly expressed. These findings supported the thesis that hair loss in PV might well be coined as "hair Nikolsky" phenomenon. This pathological pattern disappeared as the patient recovered from PV, suggesting the usefulness of assessing the hair Nikolsky phenomenon in the management of PV.
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