Erythema annulare is a general term for dermal inflammatory reactions caused by various causes, such as vasodilatation, congestion, and infiltration of surrounding white blood cells and lymphocytes. The classification of erythema annulare includes simple erythema, centrifugal erythema annulare, chronic wandering erythema and rheumatic erythema marginatum, etc. 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.