Five-year-old boy anal itch may be pinworms, anal eczema, sinusitis and other causes, need to be differential diagnosis by the doctor. 1. Pinworms: If pinworms infect the anal area, they can cause itching around the anus, which is more obvious at night. 2. Anal eczema: small pimples and papules appear on the basis of the redness of the anal skin, which can be accompanied by the symptoms of anal itching. 3. Sinusitis: due to the acute phase of sinus inflammation secretion increases, can be overflowed from the anus, resulting in anal skin moist unclean, often itchy. Parents are advised to take their children to the hospital in time, to clarify the cause of the disease, under the guidance of the doctor for standardized treatment, so as not to delay the condition of the body to bring adverse effects.