Cortical thickening in the left neck lymph nodes visible blood flow signal is ultrasound examination, often suggesting the presence of trophoblastic blood vessels in the lymph nodes leading to rapid enlargement of the lymph nodes, the possible causes of benign diseases such as infection-induced lymphadenitis, malignant diseases such as malignant tumors metastasis in the neck, the need for timely medical attention, a clear diagnosis. 1. Benign diseases: If there is a recent history of infection, such as oral ulcers, gingivitis, mumps, patients with a history of upper respiratory tract infections, ultrasound manifestation of cervical lymph nodes enlarged with abnormal blood flow signal. 2. Malignant diseases: common malignant tumors that lead to lymph node enlargement are lymphoma, thyroid cancer, if there is persistent lymph node enlargement, patients need to consult a doctor in time, perform pathological biopsy, early detection and early treatment. Patients with persistent enlargement of lymph nodes in the neck need to consult a doctor in time, complete the relevant examinations, make a clear diagnosis under the guidance of the doctor, identify the primary disease, early detection and early treatment, and try to ensure a good prognosis.