Acantholytic Hair Casts: A Dermoscopic Sign of Pemphigus Vulgaris of the Scalp

The document reports on the dermoscopic features of pemphigus vulgaris (PV) on the scalp of a 57-year-old African-American female, highlighting the presence of hair casts as a significant finding. Hair casts are movable tubular structures that envelop hair shafts and, in this case, are suggested to form through acantholysis within the outer root sheath. This mechanism for hair cast development in PV has not been previously considered in the literature. The study emphasizes that dermoscopy can be useful in assessing disease activity, particularly when scalp involvement is resistant to treatment. The presence of hair casts should alert dermatologists that acantholysis is ongoing and may indicate the need for therapy adjustment to achieve better control of the disease. This is the first report of such dermoscopic features of PV involving the scalp.