Niels Ryberg Finsen of Copenhagen developed a bulky phototherapy machine to treat skin diseases using UV light. In 1900, the French electrical engineer Gustave Trouvé miniaturized Finsen's machine with a series of portable light radiators to heal skin diseases such as lupus and epithelioma. Such machines have only been available in a chemically synthesized form since the 1970s. In the 1940s, Abdel Monem El Mofty from Cairo University Medical School used crystalline methoxsalen (8-methoxypsoralen, also called xanthotoxin) followed by sunlight exposure to treat vitiligo. This began the development of modern PUVA therapy for the treatment of vitiligo, psoriasis, and other diseases of the skin. See also Goeckerman therapy PUVA lentigines References External links Phototherapy Course, New Zealand Dermatological Society PUVA Therapy Description at Oxsoralen-Ultra Indications Light Therapy for Dermatologic Conditions at Blue Cross and Blue Shield Association of North Carolina Light therapy Ultraviolet radiation