Children with a circle in the middle of the thumb consider flat warts, eczema, ringworm, etc. The treatment includes medication, physical therapy, etc., according to the specific cause of the disease to choose the appropriate treatment. 1. flat warts: flat warts are caused by human papilloma virus infection, which is directly or indirectly infected, you can apply salicylic acid and other drugs to treat, but also through the laser, freezing and other methods to eliminate. 2. Eczema: it is a chronic inflammatory skin disease, which starts as a primary and polymorphic rash, and may also be manifested as a circle in the middle of the thumb, which can be treated by applying hydrocortisone cream, dexamethasone cream, and so on. 3. Ringworm: ringworm is a fungal infection that spreads mainly through direct and indirect contact, and can manifest itself as hyperkeratotic lesions on the fingers or palms of the hands, which can be treated with econazole and ketoconazole. The child’s thumb in the middle of a circle, should be timely to go to the hospital by the doctor to clarify the cause of standardized treatment, the above drugs need to be used under the guidance of the doctor.