Abstract: Objective To investigate the clinical, histopathological and immunopathological characteristics of erythema annulare centrifugum （EAC）. Methods A retrospective study was performed on 54 cases of EAC collected from 2001 to 2005. Information was gathered about patients′ sex, age, disease course, distribution and morphology of eruptions, symptoms, complications. Also, the findings of histopathology and direct immunofluorescence examination in some patients were evaluated. Results EAC most commonly occurred on the lower limb, and was usually complicated by various diseases among which mycosis predominated. Histological examination revealed compact lymphocyte infiltration in dermal vessels in 32 of these 54 patients. Direct immunofluorescence showed the deposition of IgG, IgM, or C3 on the walls of small vessels in 6 of 12 tissue samples tested. Conclusions EAC is a multifactorial disease, and it seems that the infiltration of lymphocytes and deposition of circulatory immune complex on small blood vessels in dermis may play important roles in its pathogenesis.

Key words: Erythema Annulare Centrifugum, Histopathology, Immunopathology