A piece of dryness on the arm like ringworm may be ringworm, psoriasis, white furfura and other diseases caused by, can take general treatment, drug treatment and other measures to improve. 1. Ringworm: for ringworm caused by a dry patch on the arm like ringworm, daily need to pay attention to personal hygiene, avoid scratching the affected area. Patients can follow the doctor’s instructions for external use of terbinafine, naftifine and other acrylamide ointment, which has the effect of killing fungi. 2. Psoriasis: a dry piece of arm like ringworm may be caused by psoriasis, daily need to use mild shower gel bath, reduce stimulation. Patients can follow the doctor’s instructions for external use of retinoic acid cream, such as tazarotene, retinoic acid cream, etc., has an anti-inflammatory effect. 3. white chaff rash: if the white chaff rash caused by a piece of dry arm like ringworm, daily need to avoid excessive cleaning. Patients can follow the doctor’s instructions for external use of gentamycin ointment, urea ointment and other drugs, has a moisturizing effect. You can also use tacrolimus ointment, flufenamic acid butyl ester ointment and other drugs, with anti-inflammatory effect. There are many reasons that lead to a piece of dryness on the arm like ringworm, it is recommended that the patient go to the hospital, clear the cause of the disease after treatment.