Erythema annulare is a general term for a dermal inflammatory response caused by various causes, such as vasodilation and congestion with surrounding white blood cell and lymphocyte infiltration. The classification of erythema annulare includes simple eclampsia, centrifugal erythema annulare, chronic wandering erythema and rheumatic erythema marginatum. It is commonly seen in patients with rheumatic immune diseases, but some infectious diseases, tumours and endocrine diseases can also cause the phenomenon. Further examination is needed to determine what the specific disease is.