Possible causes of multiple hypoechoic lymph nodes in both sides of the neck include: lymphadenitis, cervical lymph node tuberculosis, lymphoma, lymph node metastasis of malignant tumors and so on. 1. Lymphadenitis: cervical lymphadenitis is mostly caused by the spread of infections in neighboring areas, such as gingivitis, tonsillitis, acute upper respiratory tract infections and so on. It may also be caused by immune response triggered by infection, such as HIV infection, histiocytic necrotizing lymphadenitis. 2. Tuberculosis of cervical lymph nodes: Mycobacterium tuberculosis can easily invade lymph nodes and cause lymph node enlargement, which can be secondary to pulmonary tuberculosis, bone tuberculosis, etc. It is mostly seen in children and adolescents. It is mostly seen in children and adolescents. 3. Lymphoma: Lymphoma is a malignant tumor originated from lymphatic tissues, which can occur in lymphatic tissues all over the body, and is more common in superficial lymph nodes. Patients mainly show painless progressive enlargement of superficial lymph nodes, accompanied by low fever, fatigue, emaciation, night sweating and other systemic symptoms. 4. Metastasis of malignant tumors: Neck lymph nodes may be the site of metastasis of many malignant tumors, such as thyroid cancer, nasopharyngeal cancer, esophageal cancer, breast cancer and so on. It is recommended to go to the hospital as soon as possible to consult the doctor for clarifying the nature of the lymph nodes in time and then treat them accordingly.