Clinical and histopathologic characteristics of trichrome vitiligo

Background The term trichrome vitiligo describes lesions that have a tan zo ne of varying width between normal and totally depigmented skin, which exhi bits an intermediate hue. However, the pathogenesis and the histopathologic characteristics of trichrome vitiligo are unknown. Objective: Our purpose was to investigate the clinical and histopathologic characteristics and the pathogenesis of trichrome vitiligo. Methods: Four punch biopsy specimens were taken from 21 patients with trich rome vitiligo; they were from vitiliginous skin, light brown skin, perilesi onal normal skin, and normal skin as far as 5 cm from the nearest vitiligo spot. The sections were stained with hematoxylin-eosin; in selected cases, we performed immunohistochemical staining with S-100 protein and CD1a. Results: Trichrome vitiligo occurred most frequently on the trunk in active vitiligo vulgaris. Focal vacuolar degeneration of the basal cell layer and mild inflammatory cell infiltration of the epidermis and dermis were more prominent in light brown skin and perilesional normal skin than in vitiligi nous skin and normal skin. The number of melanocytes was decreased in light brown skin compared with perilesional normal skin (P < .05) and in vitilig inous skin compared with light brown skin (P < .05); a few melanocytes were observed even in skin affected by trichrome vitiligo. The number of Langer hans cells was increased in the epidermis of light brown skin and perilesio nal normal skin compared with vitiliginous and normal skin (P < .05). PUVA therapy yielded excellent repigmentation. Conclusion: Trichrome vitiligo is a variant of active vitiligo. The changes of melanocytes, keratinocytes, and Langerhans cells may be involved in the pathogenesis of depigmentation in trichrome vitiligo.