IMPACT OF NARROWBAND UVB THERAPY ON HISTOPATHOLOGICAL CHANGES IN VITILIGO: A RANDOMIZED CONTROLLED TRIAL

Narrowband ultraviolet B (NB-UVB) phototherapy has emerged as a cornerstone in vitiligo management; however, its precise histopathological impact remains inadequately characterized. This randomized controlled trial aimed to evaluate the histopathological alterations induced by NB-UVB therapy in vitiligo patients. Forty individuals with non-segmental vitiligo were randomized into two groups: Group A received NB-UVB therapy thrice weekly for 12 weeks, while Group B served as controls without phototherapy. Pre- and post-treatment skin biopsies were analyzed for melanocyte count, epidermal thickness, and inflammatory infiltrates. Results demonstrated a significant increase in melanocyte density (mean increase: 3.2 ± 0.5 cells/mm²; p<0.001) and epidermal thickness (mean increase: 0.15 ± 0.03 mm; p=0.002) in Group A compared to controls. Additionally, a marked reduction in perivascular lymphocytic infiltrates was observed post-therapy (p=0.005). These findings underscore NB-UVB's role in not only promoting repigmentation but also modulating the local immune milieu and epidermal architecture. The study introduces novel histopathological insights into NB-UVB's mechanisms, highlighting its dual action on melanocyte restoration and immune regulation.