Factors influencing the photo-reproduction of hydroa vacciniforme lesions.

Hydroa vacciniforme vesicles can be reproduced experimentally with repetitive UVA irradiations, but this photo-reproduction is not constant. The aim of this study was to search for the factors that influence photo-reproduction. To reproduce hydroa vacciniforme lesions six patients underwent repetitive UVA and polychromatic irradiations on the back. In four patients out of six, UVA irradiation with high doses induced papulo-vesicular lesions. Photo-induced lesions were very close to those induced by sunlight. Photo-reproduction failed when phototesting was done after or shortly before remission. Therefore, the absence of photo-reproduction appears to be a good prognostic factor.