Photo-Induced Sweet Syndrome: A Case Report.

Sweet syndrome is a rare dermatologic condition frequently accompanied by fever and neutrophilia. Underlying triggers and etiology of the sweet syndrome remain elusive, although infection, malignancy, medications, and more rarely, sun exposure have been associated with its development. We present a case of a 50-year-old female who developed a painful, mildly pruritic rash on sun-exposed areas of the neck, arms, and legs. She also reported chills, malaise, and nausea upon presentation. Before developing the rash, she had preceding upper respiratory infection symptoms, used ibuprofen for joint pain, and had extensive sunlight exposure on the beach. Laboratory findings were significant for leukocytosis with absolute neutrophilia, elevated C-reactive protein, and elevated erythrocyte sedimentation rate. Skin punch biopsy demonstrated papillary dermal edema with dense neutrophilic infiltration. Further evaluation for hematologic or solid organ malignancy was negative. Following the administration of steroids, the patient demonstrated significant clinical improvement. While rare, ultraviolet A and B sunlight has been shown in rare situations to be associated with the development of the Sweet syndrome. The underlying mechanism for the development of photo-induced Sweet syndrome remains unknown. However, excessive sunlight exposure should be considered a potential cause when evaluating the underlying triggers for the development of the Sweet syndrome.