AbstractAn 8–year–old boy with reticular erythematous mucinosis syndrome had erythematous plaques on his chest, face, and arms for three years. Sun exposure resulted in pruritus and increased lesions. Histologic examination revealed a perivascuiar mononuciear celi infiltrate with hematoxylln and eosin staining, positive staining materiai between the dermal coilagen bundles with alcian blue (pH 2.5) staining, and granular basement membrane deposits of IgM with direct immunofluorescence staining. Results of all lupus erythematosus serologies and porphyrin studies were negative. Minimai erythema dose determinations to ultraviolet A and B were normai, and the lesions could not be induced with high doses of irradiation. Topical sunscreens, corticosteroid cream, and systemic beta–carotene produced no therapeutic be