The occurrence of vitiligo after psoralens and ultraviolet a therapy.

The ability of photochemotherapy with 8-methoxypsoralen in conjunction with high-intensity long-wave ultraviolet light (PUVA) to stimulate melanogenesis is well known. This effect on the pigmentary system is evidenced by the diffuse tanning of clinically normal skin in PUVA-treated patients with psoriasis and other disorders, as well as by the repigmentation of lesions in vitiligo. It is now recognized that there may be additional pigmentary effects, resulting in clinical lesions such as PUVA mottling, PUVA lentigines, and localized hypopigmentation. We have documented the occurrence of yet another association with PUVA therapy--the paradoxical appearance of widespread hypopigmentation consistent with vitiligo in three PUVA-treated patients, one with psoriasis and two with mycosis fungoides. Histologic and ultrastructural findings are presented.