Topical methoxsalen administration and sunlamp fluorescent irradiation in psoriasis.

Analysis of standard fluorescent sunlamps (Westinghouse) indicates that in addition to UVB (290 to 320 nm), a considerable amount of UVA (320 to 400 nm) is also present in their emissions. Since the benefits of topical psoralen administration and UVA have already been demonstrated, and prior experience by ourselves and others with UVB has indicated that some psoriasis benefited from UVB alone, localized areas and plaques of 20 patients were treated with topical administration of psoralens and fluorescent sunlamp bulbs to determine if such a light source with this emission spectrum would be advantageous. Results indicated a total resolution in 17 of 20 patients after an average of 18 treatments. Adverse blistering phototoxic reactions and excessive hyperpigmentation were not encountered. The UVB erythema response of normal skin served as the guide to light dosage in the same manner as administration of the Goeckerman regimen. Therefore, the use of psoralens was very effective when combined with fluorescent sunlamp irradiation; however, the potential risks of photocarcinogenicity makes this treatment experimental and should be reserved for recalcitrant cases.