Antinuclear antibodies in patients with polymorphic light eruption: a long-term follow-up study.

Background: Previous studies have shown elevated titres of antinuclear antibodies (ANA) in 2.9-19% of patients with polymorphic light eruption (PLE). A diagnosis of lupus erythematosus (LE) was finally established in some of these ANA-positive patients.
Objectives: To investigate whether the presence of ANA in patients with PLE merely represents an epiphenomenon or is associated with an increased risk of eventual progression to LE.
Methods: We identified 472 patients with PLE who had received prophylactic photo(chemo)therapy between 1986 and 2003 and were routinely tested for the presence of ANA. All ANA-positive (ANA titre of>or=1:80) patients were asked to attend for a follow-up examination comprising a medical history, complete skin inspection and a detailed laboratory analysis including ANA and antibodies against extractable nuclear antigens.
Results: Of all the patients, 55 (11.7%) were found to be ANA positive on one or several occasions, and three (0.6%) also had antibodies to SS-A/Ro. Thirty-nine (71%) of all ANA-positive patients including all Ro+ subjects were available for follow-up after a median follow-up period of 8 years (interquartile range 5-11.5). Twenty-five patients showed persistence of ANA positivity with a median titre of 1:160 (range 1:80-1:640), whereas in 14 patients ANA titres had returned to normal levels. None of the patients revealed additional clinical, histopathological or laboratory abnormalities suggestive of LE.
Conclusions: After a median follow-up period of 8 years none of the ANA-positive patients developed LE. Our findings indicate that PLE is a benign disease without tendency to progress to LE.