Lymph nodes are lymphatic structures in the human body, mostly oval in shape, scattered throughout the body in various lymphatic return pathways, such as the neck, armpits, groin, N, elbow, mesentery and lung gates. Lymph node enlargement is very common and can occur in people of any age and can also be seen in a variety of diseases. So, which diseases are most likely to cause swollen lymph nodes? Which lymph node enlargements are the most dangerous? What tests must be done to rule out malignant lymphoma? I. The three most common diseases 1. Various infections: Bacterial infections, such as acute inflammation in the mouth and face, often cause swollen lymph nodes in the jaw, and the swollen lymph nodes have a soft texture and good mobility, accompanied by pain and fever. They usually return to normal gradually with the disappearance of inflammation. Viral infections, such as measles and infectious mononucleosis, can cause enlarged lymph nodes. In addition, allergic reactive diseases and poisonous insect stings can also cause swollen lymph nodes. 2. Chronic lymphadenitis: most of them have obvious foci of infection and are often confined lymph node enlargement with pressure pain, usually not more than 2 to 3 cm in diameter, which will shrink after anti-inflammatory treatment. Enlarged inguinal lymph nodes, especially flat lymph nodes that have been present for a long time without change, are mostly of no importance. However, enlarged cervical and supraclavicular lymph nodes without obvious causes signify systemic lymphoid tissue proliferative diseases, which should be taken seriously and further examined to determine. 3.Tuberculous lymphadenitis: swollen lymph nodes in the neck are common, with fever, excessive sweating, weakness, and increased blood sedimentation, mostly in young adults. They are often accompanied by pulmonary tuberculosis, and the lymph nodes are uneven in texture, with some parts being soft (cheese-like changes) and some parts being hard (fibrosis or calcification), and adhering to each other and to the skin, so they are poorly mobile. These patients have positive tuberculin tests and blood antibodies to tuberculosis. Malignant lymphoma: It can be seen at any age, and the enlargement of lymph nodes is often painless and progressive, which can range from soybean to date size, with medium hardness. They are generally not adherent to the skin, do not fuse with each other in the early and middle stages, and can move. In the later stages, the lymph nodes may grow to a large size or fuse into a large mass with a diameter of 20 cm or more, invade the skin, and remain untreated for a long time after rupture. In addition, it can invade mediastinum, liver, spleen and other organs, including lung, digestive tract, bone, skin, breast, nervous system, etc. 2.Lymph node metastasis cancer: this kind of lymph nodes are very hard, without pressure pain and inactive, especially in patients with stomach cancer and esophageal cancer, the lymph nodes on the clavicle can be touched to be enlarged. It is seldom generalized lymph node enlargement. Breast cancer patients should often touch the lymph nodes under the armpit to determine whether the tumor is metastatic. 3.Leukemia: The swollen lymph nodes in leukemia are generalized, but most obvious in the neck, axilla and groin, especially acute lymphoblastic leukemia which is common in children. The clinical onset is rapid, often accompanied by fever, bleeding, enlarged liver and spleen, and sternal pressure pain. Hematology and bone marrow aspiration tests can confirm the diagnosis and identification. Third, three tests must be done 1, hematology doctor examination and analysis: hematology doctor specializing in this stuff, more experience. Generally check the chest X-ray, CT, ultrasound, immune indicators, tumor indicators. Biochemistry, inflammation indicators. 2.Pathological biopsy: So once abnormally enlarged lymph nodes are found, pathological biopsy should be performed as soon as possible, and surgical removal of superficial lymph nodes is preferred. Fine needle aspiration is suitable for deep lymph nodes and organs suspected to have lesions in the body, or swollen lymph nodes suspected to have recurrence after treatment. These tests are safer and usually do not cause tumor spread and metastasis. 3. Bone marrow aspiration: This is also the watchword of hematologists. In clinical practice, in order to accurately determine the clinical stage of malignant lymphoma and develop a treatment plan, doctors also routinely perform whole-body and bone marrow aspiration examinations before the first treatment. Newer tests, such as PET/CT, have an important role in the diagnosis of malignant lymphoma. In conclusion, for most people, the causes of swollen lymph nodes are sore throats, colds, inflammation of the teeth (abscesses), ear infections or insect bites. However, as the incidence of malignant lymphoma increases year by year, people should be alert, especially if the swollen lymph nodes appear in the middle of the front of the neck or just above the clavicle, or if the lymph nodes are persistently enlarged, hardened and inactive, they should be seen by a hematologist as soon as possible to receive timely and effective treatment.