Erythema annulare on the leg of a middle-aged woman. Erythematous streaks in bow-shaped or circular form, often slightly raised, are visible on the skin. The cause usually remains unsolved, but an underlying infection, drug reaction or, in a particularly severe disease, even a malignancy may be found. The circles will expand within days or weeks. The disease is rare. Instead, urticaria often has a similar appearance, but the rash will change its location and shape during the day. Other diseases to be borne in mind include fungal rashes, psoriasis, cutaneous borreliosis and cutaneous lupus erythematosus. An assessment by a dermatologist is therefore often necessary.