Enlarged lymph nodes with a regular shape and poorly defined medulla are most commonly seen in bacterial and viral infections, as well as in tuberculosis and tumors. Lymph nodes are found all over the body and are important immune organs. Bacterial or viral infections or diseases such as tuberculosis or tumors can cause the lymph nodes to change shape and have an abnormal texture. Therefore, if you have enlarged lymph nodes, you should consult a doctor promptly. Lymph node enlargement can be seen at any age and is clinically categorized into benign, malignant and junctional lymph node enlargement. 1. Benign lymph node enlargement: it is commonly caused by various infections and can recover within a certain period of time after removing the cause. It can be divided into non-specific lymphadenitis and specific infectious lymph node enlargement. Non-specific lymphadenitis is mostly characterized by lymph node enlargement caused by acute and chronic inflammation of local tissues. And specific infectious lymph node enlargement is common in lymphatic tuberculosis, filarial infection, venereal disease and so on. 2. Malignant lymph node enlargement: it is mostly seen in malignant tumors, such as malignant lymphoma, leukemia, metastatic cancer of lymph nodes and so on. 3. Junctional malignant lymph node enlargement: seen in angioimmunoblastic lymphadenopathy and giant lymph node hyperplasia. There is a possibility of malignant transformation in later stages. Enlarged lymph nodes with regular shape and unclear medulla can also be seen in systemic infectious diseases, tuberculosis, systemic lupus erythematosus and other diseases, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment.