Lymphocytic infiltration of the skin is a photosensitive variant of lupus erythematosus: evidence by phototesting

Background Lymphocytic infiltration of the skin (LIS) is a disorder in whic h photosensitivity has been suspected but never proven. Objectives To carry out a systematic photobiological investigation in patie nts with LIS and to compare the photobiological features of LIS with those of other photosensitive disorders. Methods We performed provocative phototesting with ultraviolet (UV) A and U VB in 10 patients with active LIS. Results In all patients, UVA and/or UVB elicited abnormal papular phototest reactions resembling lesions of LIS both clinically and histologically. Le sions typically developed 3-6 days (mean +/- SD 100.8 +/- 20.9 h) after the first UV exposure, Conclusions This characteristic latency interval together with certain clin ical features, i.e. onset in summer, predilection for the face and persiste nce of the lesions, indicate that LIS is a photosensitive disorder distinct from polymorphic light eruption but indistinct from lupus erythematosus (L E). Both our photobiological findings and the effective treatment with hydr oxychloroquine in half of our patients strengthen the proposal that the two entities LIS and LE tumidus are identical, As diagnosis cannot be made by histological, immunofluorescence or laboratory criteria, provocative photot esting may be a diagnostic aid in this disorder.