Polymorphous light eruption: Experimental reproduction of isomorphic skin lesions by a new method

Using a new phototest procedure, experimental lesions have been elicited in twelve patients with clinical diagnosis of polymorphous light eruption (PLE), papular type. A skin area (5 x 10 cm), in which the patient had had genuine eruption of PLE, has been daily irradiated with polychromatic UVB (80% of MED) + UVA (25 J/sq cm) + VIS (170 J/sq cm). All patients showed a papular eruption after 3-7 irradiative sessions. No response was observed on the control area receiving only polychromatic UVA (60J/sq cm) in repeated sessions (up to ten), according to Holzle's method. Our results suggest that the interaction among different wavelengths could play an important role in the pathogenesis of PLE.