Activation of melanoblasts and melanocytes after treatment with monochromatic excimer light and narrowband-ultraviolet B of skin of vitiligo patients.

BACKGROUND

Vitiligo is a hypopigmentation disease characterized by achromatic or hypochromatic macules in several sites of human skin. Although monochromatic excimer light (MEL) and narrowband-ultraviolet B (NB-UVB) have recently been used for efficacious treatment of vitiligo, the repigmentation process and role of melanocytes/melanoblasts are not well known.

METHODS

White macules of 28 vitiligo patients were repeatedly exposed with MEL/NB-UVB. After the exposures, punch biopsies of the center and edge of the lesional skin in addition to normal skin were fixed and processed to dopa and combined dopa-premelanin reactions. Melanocytes positive to the dopa reaction and melanoblasts/melanocytes positive to the combined dopa-premelanin reaction were surveyed.

RESULTS

Two repigmentation patterns were observed; one was "marginal" and the other was "perifollicular." Although the frequency of the former pattern was much lower than that of the latter pattern, no differences were observed in average percentage of repigmentation and the number of melanocytes and melanoblasts observed at the center and edge of the lesional epidermis.

CONCLUSIONS

These results suggest that exposures with MEL/NB-UVB induce the marginal or perifollicular repigmentation pattern in the white macules, though the two patterns produce no differences in the distribution and density of melanoblasts/melanocytes in the lesional epidermis.