Photochemotherapy (PUVA) in psoriasis and vitiligo.

Phototherapy with photochemotherapy (PUVA) is a well‑known and well‑studied modality for the treatment of psoriasis, which involves systemic or topical administration of chemicals known as psoralens and administration of ultraviolet light in increasing dosages after requisite time gap. PUVA is also used in the treatment of widespread vitiligo with moderately good results, though it is being surpassed by ultraviolet B (UVB), which is equally or slightly more efficacious with fewer side effects. PUVA induces repigmentation by varying mechanisms such as stimulation of melanogenesis, immunomodulation and activation of growth factors, though the exact mechanism is still speculative. There are various studies evaluating the efficacy of PUVA in psoriasis as well as in vitiligo, either alone or in combination with other immunosuppressants like azathioprine and calcipotriene.