There is a small bag behind the child’s ear, may be caused by tonsillitis, mumps, otitis media and other inflammatory factors caused by the lymph nodes behind the ear swelling, there may be localized folliculitis behind the ear, sebaceous cysts and other diseases. It is recommended to go to the ear, nose and throat department of the hospital and follow the doctor’s instructions for treatment. 1. swollen lymph nodes: children with tonsillitis, mumps, otitis media, often violates the lymph nodes behind the ear, acute stage may also be accompanied by pain, redness, swelling, fever and other symptoms. 2. Folliculitis: when the hair follicle behind the ear is infected, red papules or pustules centered on the hair follicle can be formed. 3. Sebaceous cysts: Because the sebaceous glands behind the ear secrete more vigorously, excessive sebum secretion when blocking the mouth of the hair follicle may lead to sebaceous cysts, usually painless small packets, stimulate the infection may appear red, swollen, painful symptoms. Parents should pay attention to the nature and mobility of the pouch when there is a small pouch behind the ear of a child. It is recommended to consult a doctor in time to find out the cause of the disease and then treat the cause and symptom.