The Science and (Lost) Art of Psoralen Plus UVA Phototherapy.

PUVA phototherapy is the therapeutic use of psoralens and UVA light to treat inflammatory skin diseases, with psoriasis the prototype disease. Naturally occurring phototoxic compounds, psoralens interact with UVA to suppress DNA synthesis and cell proliferation and induce apoptosis of inflammatory cells. Well-developed therapeutic protocols for psoriasis guide psoralen and UVA doses, treatment frequency, and safety measures, and these protocols also may be used to treat other inflammatory dermatoses.