A small red itchy patch of skin may be associated with papular urticaria, eczema, folliculitis, contact dermatitis, and the specific disease needs to be determined by a doctor. 1. papular urticaria: related to mosquito bites, mainly manifested as localized raised bumps, often accompanied by redness, itching and so on. 2. Eczema: Skin contact with some easily induced allergic substances, such as ultraviolet rays, animal fur, pollen, etc., may cause eczema, red itchy skin symptoms. 3. Folliculitis: not paying attention to the surface of the body clean, the hair follicle area is stimulated by inflammation, may lead to localized skin lesions, appearing red itchy skin. 4. contact dermatitis: when the skin is in contact with unclean objects, contact dermatitis may also appear red itchy symptoms. A small piece of red itchy skin is recommended to consult a doctor in a timely manner to clarify the cause of the disease under the guidance of the doctor to treat the symptoms.