Clinical, laboratory, phototest and phototherapy findings in polymorphic light eruptions: a retrospective study of 133 patients.

In the present study, we retrospectively evaluated the clinical, laboratory, phototest and phototherapy findings in 133 patients (109 females and 24 males) with polymorphic light eruption (PLE). The median age of the patients at onset of PLE was 26 years (range, 3-62 years). The median duration of PLE at presentation was 6.5 years (range, 1 week to 25 years). Interestingly, we found two peaks in the distribution curve of the individual latent interval, the time between light exposure and the appearance of skin lesions. The first peak occurred at 1-1.5 hr and the second peak at 24 hrs after light exposure. Six of 33 patients tested had antinuclear antibodies (ANA). However, none of these ANA-positive patients had or developed systemic lupus erythematosus during follow-up. Phototesting revealed that minimal erythema doses for UVA and UVB fell within normal limits in 30 patients tested. Provocative phototesting was positive in 17 of 30 (57%) patients tested. The action spectrum fell within the UVA range in 10 (59%), the UVB range in 4 (23%), and both ranges in 3 (18%) of the 17 cases. Ninety-two patients received preventive phototherapy including broad-band UVB, broad-band UVA, or psoralen and ultraviolet A (PUVA). Follow-up information was available for 79 of these patients: the complete protection rate in the first summer season after therapy was 27% for UVB, 0% for UVA, and 53% for PUVA whereas the overall protection rate (including partial and complete responders) was 83% for UVA, 82% for UVB and 65% for PUVA. In contrast, the patients' histories revealed that the use of a sunscreen with a mean sun protection factor (SPF) of 14 did not prevent skin lesions in 88% of PLE patients.