Infants with hard bumps behind the ears are usually localized lymph nodes. In normal children, tough lymph nodes, about the size of a soybean, can be palpated behind the ear, behind the neck, behind the occiput, and in the jaw. If there is localized light pressure pain, enlarged lymph nodes, or multiple lymph nodes fused together, this is indicative of lymphadenitis of the neck, mostly due to reactive hyperplasia of the lymph nodes in response to bacterial infection, upper respiratory tract infection, or systemic inflammation. Most of the lesions are benign, and only a very small number of children have malignant lesions such as lymphoma. Pathological examination is the gold standard for differentiating benign lesions from malignant ones. Generally, it is also possible to determine initially whether the internal structure of the lymph nodes is clear, whether there are changes in the medullary cortex, and whether there are multiple fusions under ultrasound low, which can also be used as a differentiator. Therefore, hard bumps behind the ear are usually benign lymph node hyperplasia and do not require much treatment.