PHOTOCHEMOTHERAPY BEYOND PSORIASIS

Photochemotherapy involves the therapeutic use of nonionizing radiatio n in combination with a photosensitizing chemical to trigger a photoch emical reaction that mediates a beneficial effect. The successful intr oduction and widespread use of psoralen photochemotherapy (PUVA) in th e management of psoriasis was the chief stimulus for recent interest i n the therapeutic use of nonionizing radiation in various other dermat oses. This article discusses the expanding spectrum of diseases respon ding to PUVA therapy. More than 30 condition's such as atopic dermatit is, mycosis fungoides, vitiligo, the photodermatoses, chronic graft-ve rsus-host disease, and granuloma annulare have been successfully treat ed with oral psoralen photochemotherapy. Various mechanisms of respons e to treatment are discussed including photoimmunologic effects, selec tive cytotoxicity, alterations of cell function, and stimulation of me lanocytes. Finally, the limitations to the use of PUVA therapy are ide ntified and its future use in other cutaneous and systemic diseases ar e discussed.