PUVA therapy

PUVA (psoralen and ultraviolet A) is an ultraviolet light therapy treatment for eczema, psoriasis, graft-versus-host disease, vitiligo, mycosis fungoides, large-plaque parapsoriasis and cutaneous T-cell lymphoma using the sensitizing effects of the drug psoralen.:686 The psoralen is applied or taken orally to sensitize the skin, then the skin is exposed to UVA. PUVA (psoralen and ultraviolet A) is an ultraviolet light therapy treatment for eczema, psoriasis, graft-versus-host disease, vitiligo, mycosis fungoides, large-plaque parapsoriasis and cutaneous T-cell lymphoma using the sensitizing effects of the drug psoralen.:686 The psoralen is applied or taken orally to sensitize the skin, then the skin is exposed to UVA. Photodynamic therapy is the general use of nontoxic light-sensitive compounds that are exposed selectively to light, whereupon they become toxic to targeted malignant and other diseased cells. Still, PUVA therapy is often classified as a separate technique from photodynamic therapy. Psoralens are materials that make the skin more sensitive to UV light. They are photosensitizing agents found in plants naturally and manufactured synthetically. Psoralens are taken as pills (systemically) or can be applied directly to the skin, by soaking the skin in a solution that contains the psoralens. They allow UVA energy to be effective at lower doses. When combined with exposure to the UVA in PUVA, psoralens are highly effective at clearing psoriasis and vitiligo. In the case of vitiligo, they work by increasing the sensitivity of melanocytes, the cells that manufacture skin color, to UV light. Melanocytes have sensors that detect UV light and trigger the manufacture of brown skin color. This color protects the body from the harmful effects of UV light. It can also be connected to the skin's immune response.