Experimental reproduction of polymorphous light eruption and benign summer light eruption by whole-body UVA irradiation.

The entity 'benign summer light eruption' (BSLE) has been introduced to make a clinical subdivision in the heterogeneous group of polymorphous light eruptions (PLE). Provocation tests for PLE are not always easy to perform and require expensive apparatus. Our purpose was to evaluate a provocation test that could be readily done by a dermatologist with a UVA cabin. Provocation tests are currently required in order to obtain a financial contribution from the social security services in Belgium. In addition, we were interested in determining whether the results of the provocation test would permit us to differentiate between the clinical entities of BSLE and PLE. We studied the efficacy of whole-body UVA irradiation for BSLE and PLE patients. A total of 45 patients was tested, of whom 26 were diagnosed as having BSLE and 19 PLE. In the BSLE group, 24 patients (92%) presented lesions. In the PLE group, 15 patients (79%) had a reaction, but 3 had a positive UVB test. The mean dose to induce lesions was 65.96 J/cm2 for the BSLE group and 52.86 J/cm2 for the PLE group. We conclude that the whole-body UVA test is a high-performance provocation test for both BSLE and PLE patients although it cannot differentiate the two entities from one another.