The initial consideration for a patch of bumps on the body when scratched is urticaria. Urticaria is a kind of disease that produces windy bumps and angioedema after exposure to stimuli. The causes of urticaria are complicated, such as food, drugs, sunlight, stress, heat and cold, insects, heredity, and mental factors. Itching of the skin often occurs first, followed by the appearance of the wind, which appears red or white, skin color, etc., with different sizes and shapes, and the duration of the attack is also uncertain. Skin scratching sign is a type of urticaria, which is a condition in which the patient develops windmills on the skin after a few minutes of hand scratching or mild mechanical irritation. It is not clear whether the patient has had other irritants before scratching, and other diseases cannot be ruled out, so he should go to the hospital in time and be diagnosed by a professional doctor.