Poliosis, an absence of functional melanocytes of affected hair follicle, is considered a poor prognostic factor in treatment of vitiligo because the melanocytes of hair follicles are the major source of repigmentation. We sought to evaluate the clinical outcome of poliosis in treatment of vitiligo.
An open-label pilot study was performed between January 2016 and March 2018. Patients with vitiligo who have poliosis in head and neck were treated with the combination therapy of 308-nm excimer laser, topical tacrolimus, and intralesional triamcinolone injection for more than 3 months. Dermoscopy was used to evaluate the lesions thoroughly.
A total of 21 patients (2 males and 19 females; mean age: 58 years) were enrolled.  Perifollicular repigmentation associated with poliosis was observed in 11 patients (52.4%). Five patients were segmental vitiligo and the others were non-segmental vitiligo. It occurred even after 6 months of the combination treatment, whereas most cases of perifollicular repigmentation without poliosis started within 1 month. 
Hair follicles are considered the reservoir of melanocytes in vitiligo, and the treatment is not easy where poliosis is present. However, we observed the perifollicular repigmentation associated with poliosis with the continuous treatment. These findings would be explained with both activation of inactive amelanotic melanocytes and differentiation of melanoblast, and melanocyte stem cells in hair follicle.

Late perifollicular repigmentation associated with poliosis