Positive photobiological investigation in reticular erythematous mucinosis syndrome.

BACKGROUND Reticular erythematous mucinosis (REM) syndrome is a rare disorder. Its clinical course is cyclic with remissions and exacerbations. In this disease, photosensitivity has previously been noticed but rarely demonstrated. We report three new cases with positive photobiological investigation. CASE REPORTS Three patients (two males, one female) with a mean age 47 years were seen with reticular erythematous papules on the upper chest and or back. After sun exposure, the lesions were exacerbated. Skin biopsies showed dermal lymphocytic perivascular infiltration with mucin deposition between collagen bundles. Direct immunofluorescence was negative. Antinuclear antibodies were absent. In cabin, ultraviolet (UV)A exposure reproduced clinically and histologically REM lesions in our cases. UVA and UVB provocating phototests were negative. In all patients treatment with oral antimalarials and external photoprotection was effective. CONCLUSIONS In our patients, we confirm the photosensitive feature of REM syndrome by provocative irradiation in UVA cabin. The mechanism of triggering is actually unclear. It is supposed that UV radiation, heat, and perspiration are necessary to reveal this affection.