Enlargement of lymph nodes at the back of the head is mostly considered to be caused by inflammatory lesions, lymphoma, lymphatic metastasis and other factors. 1. Inflammatory lesions: If there are inflammatory lesions such as otitis media and mastoiditis, the inflammation will involve the surrounding lymph nodes, thus resulting in swollen lymph nodes at the back of the head. 2. Lymphoma: if suffering from lymphoma, there will be multiple lymph node enlargement in the whole body, which will lead to lymph node enlargement at the back of the head. 3. Lymphatic metastasis: if there is cranial malignant tumor in the body, the tumor cells may metastasize to the lymph nodes, resulting in swollen lymph nodes at the back of the head. Lymph node swelling at the back of the head is also seen in other reasons, it is recommended to consult a doctor in time, and actively diagnose and treat, so as to avoid delaying the condition.