Patterns of repigmentation in two cases of hypopigmented type of vitiligo

It has been observed that depigmentation in vitiligo passes through two stages; patches of light brown hypopigmentation which gradually changes into milky white patches. In this work, we studied two cases of hypopigmented vitiligo regarding the melanocytes and keratinocytes' changes before and after 7 months of psoralen plus ultraviolet A (PUVA) therapy. Skin biopsies were taken from the vitiliginous lesions before and after 7 months of PUVA therapy and were examined using haematoxylin and eosin and Masson Fontana stains, l-3,4-dihydroxyphenylalanine reaction, immuno-histochemical stains and ultrastructural examination. In the pretreated patients, the melanocytes present were inactive and degenerative changes were detected in both melanocytes and keratinocytes. After PUVA therapy, obvious histopathological improvement was detected. Clinically, the initial response to PUVA therapy was increased hypopigmentation indicating that degenerated cells in the vitiliginous patches might have continued the process of degeneration and did not recover. Meanwhile, the perifollicular and marginal pigmentation suggested that pigmentation occurred from those areas and not from activation of already degenerated melanocytes.