Abstract: CHILBLAIN LUPUS ERYTHEMATOSUS IN A MONOLYGOTE TWIN.#C. Chams, M. Akbarian, P. Mansoori, F. Shahram, and F. Davatchi#Revista Espanola de Reumatologia, 1993; 20 (Suppl 1): p. 358 #Chilblain lupus erythematosus or lupus pernio was described by HUTCHINSON in 1888. Even actually it is difficult to put this entity in a well defined nosologic place as systemic lupus erythematosus. We report here the case of a twin monozygote brothers of 11 years old, premature, who had developed soon in their life lesions of chilblain lupus erythemathosus. Skin lesion appears at autumn and disappears at spring time every year. One of the brothers had not improved since the last year and developed important cutaneous lesions on his fingers, ears, nose and on his body. The preclinical. investigations for SLE including FANA, Anti DNA, C3, C4, VDRL, Anticardiolipin antibodies, and LE cell were all negative. However the pathology of the skin lesions were suggestive for SLE. At our best knowledge this is the first case of chilblain lupus erythematosus ever reported in the literature in a monozygote twin brothers. The occurrence of chilblain lupus in monozygote twins may be in favor of a genetic predisposing factor in the pathophysiology of the disease. Due to it's different symptomatology it may a separate entity from lupus erythematosus.