Sun-induced life-threatening lupus nephritis

Photosensitivity is a widely known characteristic of both cutaneous and systemic lupus erythematosus (LE). However, sun-induced organ involvement is rarely reported in LE. We describe a 34-year-old woman who had been in complete remission of systemic LE for more than 8 years without treatment. After sunbathing, she developed acute sunburn followed by cutaneous LE in sun-exposed areas. Six weeks later, a lupus nephritis was diagnosed and high serum levels of anti-double-stranded (ds) DNA and anti-Ro/SSA antibodies were detected. Treatment with systemic cyclophosphamide and prednisolone led to septicemia requiring assisted ventilation for more than 2 weeks and repeated hemodialysis. Clinical remission was achieved 3 months later by the use of prednisolone and mycophenolate mofetile. Meanwhile, mild proteinuria persisted, anti-dsDNA antibodies normalized. We hypothesize that the sunburn-induced keratinocyte necrosis/apoptosis exposed intracellular antigens as trigger for the generation of autoantibodies that finally mediated immune-complex nephritis. The patient highlights the impact of UV light not only on skin but also on internal organ involvement in LE.