Lymph nodes are important immune organs of the human body and are distributed in various parts of the body. On the surface of the body, they are mainly distributed in the neck, armpits and bilateral inguinal areas. In the body cavity, they are mainly distributed in the mediastinal cavity and the root of the omental mesentery of the abdominal cavity. These lymph nodes are under 0.5 cm under normal conditions and are relatively soft in texture. Since lymph nodes are important organs for processing metabolic wastes and dealing with infected lesions, once infection or tumor metastasis occurs, lymph nodes will appear to increase in size for unknown reasons. In case of inflammatory lymphadenitis, there may be localized enlargement of lymph nodes or obvious pressure and pain. In the case of tumor metastasis, the lymph nodes are mostly painless. Lymph node enlargement is persistent and occurs in clusters, especially in hematologic or lymphatic tumors, in which the enlarged lymph nodes are abnormally large, and the cause of the lymph node enlargement can often be clarified by a puncture biopsy.