Enlarged lymph nodes on the clavicle may be caused by the following reasons: infectious factors, lymphoma, lymph node metastasis, etc. 1. Infectious factors: when infected by certain bacteria or germs, it will lead to the phenomenon of swollen lymph nodes on the clavicle, such as inflammation of the tissues around the lymph nodes, the inflammation may spread to the lymph nodes, which will lead to lymphadenitis; there are also syphilis, tuberculosis and so on, which can lead to the emergence of localized lymph nodes, resulting in the enlargement of lymph nodes on the clavicle. 2. Lymphoma: this is a malignant tumor of the blood system, which may lead to the enlargement of multiple lymph nodes, and the clavicular lymph nodes may also be enlarged. 3. Lymph node metastasis: if malignant tumor occurs, such as thyroid cancer, stomach cancer, etc., the tumor cells may be transferred to clavicular lymph nodes, which is called lymph node metastasis, and the lymph nodes on the clavicle will be enlarged. Patients need to go to the hospital for consultation, and need to improve relevant examinations, such as ultrasound, CT, blood routine, etc. Sometimes, lymph node biopsy is needed, which can usually clarify the cause.