Causes of circular spots on the skin include ringworm, granuloma annulare, nummular eczema, drug reactions and psoriasis, according to Dr. Alan Greene. Ringworm is a fungal infection of the skin that causes ring-like patches to form on the skin, notes Healthline.
Ringworm is spread through direct contact with infected humans, animals or soil, explains Healthline. Patients with a ringworm infection of the skin have skin patches that blister or ooze, have defined edges and are red and raised. The infection is treated with antifungal medications and skin creams.
Granuloma annulare is a chronic skin disease that presents itself as a rash with bumps arranged in a circle, according to MedlinePlus. Doctors do not know what causes the condition, which is occasionally associated with diabetes or thyroid disease. In rare cases, patients experience widespread itching and firm nodules under the skin in addition to the skin rash. Treatment for granuloma annulare is usually done for cosmetic purposes and consists of steroid creams and injections.
Nummular eczema is an allergic condition that causes coin-shaped patches to appear on the skin, notes MedlinePlus. Although doctors do not know what causes the condition, it is usually present in people who have a family history of allergies, atopic dermatitis and asthma. Patients with nummular eczema experience itchy and scaly skin as well as skin inflammation. Factors that make symptoms of nummular eczema worse include stress, temperature changes and dry skin.