Small bumps behind the ears may be due to folliculitis, enlarged lymph nodes, sebaceous cysts and other reasons. 1. Folliculitis: there are abundant hair follicle tissues behind the ear, and factors such as skin trauma and breakage lead to bacterial infection of hair follicle tissues, causing inflammatory follicular exudation, congestion and other lesions, and the hair follicles become enlarged, so this symptom will appear. 2. Enlarged lymph nodes: swollen lymph nodes behind the ear can be divided into benign and malignant, benign lymph node enlargement usually has pressure and pain, the surface can be red and swollen, mostly accompanied by local inflammation, such as mumps, tonsillitis, etc.; malignant lymph node enlargement is usually progressive enlargement, lymph nodes usually have no pressure and pain, and may be related to lymphoma, leukemia, nasopharyngeal carcinoma, and other malignant tumors. 3. Sebaceous cysts: long-term lack of local skin cleaning leads to blockage of sebaceous gland ducts behind the ear by a large amount of secretion, sebum discharge is blocked, and long-term accumulation leads to the formation of sebaceous cysts, which is why this symptom occurs. It is recommended to consult the hospital to clarify the cause of the disease.