The lymph nodes in the left posterior cervical region have been peanut-sized for a year, which may be the manifestation of chronic lymphadenitis, lymphocysts or metastatic lymph node enlargement. 1. Chronic lymphadenitis: When chronic lymphadenitis occurs, the body may be infected by bacteria or viruses, tuberculosis and other pathogens, leading to hyperplasia and hypertrophy of lymph nodes, which will last for about a year without any obvious changes. 2. Lymphocysts: Sometimes the return of lymphatic fluid is blocked, which may lead to the accumulation of lymphatic fluid in the lymph nodes and the formation of fluid cysts, and the left posterior cervical lymph node of peanut size for more than a year may also occur. 3. Metastatic lymph node enlargement: when there are tumors in breast, mediastinum, lungs, etc., if the degree of malignancy is not high, lymph node metastasis occurs, and the growth is relatively slow, the same lymph node of peanut size will be formed in the left posterior neck, and the change is not obvious after one year, but the volume will continue to increase slowly. When you find that the left posterior neck lymph nodes present the size of a peanut for a year, it is best to consult a doctor in time to carry out a pathological biopsy to clarify the cause of the disease, and accept the appropriate treatment, so that you can slowly return to normal.