Histopathological and Immunohistochemical Study of Hypopigmented Patches in Trichrome Non-Segmental Vitiligo

Introduction: Vitiligo is a multifactorial autoimmune disease. A comprehensive understanding of the pathogenesis within the trichrome area, particularly of the role of CD8+ and CD4+ T lymphocytes, is crucial to developing effective therapeutic strategies. Objectives: We aimed to characterize the distinct histopathological and immunohistochemical features of trichrome non-segmental vitiligo, with a specific focus on CD4+ and CD8+ T lymphocyte populations within different pigmentary zones of a single lesion to elucidate the pathogenesis of this vitiligo subtype. Methods: Thirty patients with trichrome non-segmental vitiligo were enrolled. Four mm skin punch biopsies were obtained from vitiligo, trichrome, and adjacent apparently normal skin areas of each patient. Biopsies were immunohistochemically stained to assess the expression of CD4+ and CD8+ T cells. Results: The study revealed a statistically significant difference in CD4+ T cell count across vitiliginous, trichrome, and apparently normal skin areas (P<0.001), with significantly higher values in the vitiliginous area than the apparently normal skin, and both elicited significantly higher values than the trichrome area. CD8+ T cell count was significantly different across the three skin areas (P<0.001), being significantly lower in the vitiliginous area than the trichrome and significantly higher in both than in the apparently normal skin area. Furthermore, a significant positive correlation was found between VIDA scores and CD8+ T cell numbers in trichrome areas (r=0.688, P<0.001). Conclusion: The trichrome area represents a critical area to consider in the development of effective treatment strategies for vitiligo.