The enlarged lymph nodes in the neck of 2.1×0.8 cm are considered to be possibly related to infection, rheumatism and immunity, tumor and other factors. 1. Infection: When the body’s immunity is low, it is easy to be infected by bacteria, viruses and other pathogenic microorganisms. Especially infections occurring in the upper respiratory tract can easily lead to reactive hyperplasia of the lymph nodes in the neck. 2. Rheumatic immunity: patients with rheumatoid arthritis, systemic lupus erythematosus and other rheumatic immune diseases have abnormal immune system function. Lymph nodes belong to an important part of the immune system and are easily enlarged. 3. Tumor: The most common tumor that leads to enlarged lymph nodes in the neck is malignant lymphoma. Suffering from lung cancer, liver cancer and other diseases, the tumor tissues can also be transferred to the lymph nodes in the neck, thus causing the enlargement of lymph nodes in the neck. There may be other clinical causes of enlarged lymph nodes in the neck 2.1×0.8 cm, so it is recommended to go to the hospital as soon as possible in order to clarify the cause of the disease.