Lymph nodes are important immune organs of the body, which are the sites of immune response to antigenic stimulation and have filtering, proliferation and immune functions. Normal superficial lymph nodes are small, mostly within 0.5 cm in diameter, with smooth and soft surface, no adhesion with surrounding tissues and no pressure pain. When the body is attacked by disease-causing factors, information is transmitted to the lymph nodes, and lymphocytes produce lymphokines and antibodies to effectively kill the disease-causing factors. As a result of the “struggle” between the two, lymphocytes and histiocytes in the lymph nodes proliferate reactively, causing the lymph nodes to swell. The causes of swollen lymph nodes in the neck are very complex and sometimes it is difficult to obtain a definite diagnosis even with the examination of tissue sections. Analysis of the causes of enlarged lymph nodes in the neck includes 3 aspects, namely infection, tumor and other factors. 1. Infectious factors: bacterial – bacterial infections of the teeth, tonsils, face or scalp, tuberculosis, syphilis, cat-scratch disease, Lyme disease; viral – herpetic stomatitis, infectious mononucleosis, HIV infection (AIDS disease); parasitic – toxoplasmosis; unknown causes: skin mucosa lymph node syndrome (Kawasaki disease), subacute necrotizing lymphadenitis (Kikuchi disease). 2, tumor factors: primary – Hodgkin’s disease, non-Hodgkin’s lymphoma, leukocytes, especially lymphocytic leukemia; secondary – cancer (metastatic tumors of the oral cavity, salivary glands, nasopharynx), malignant melanoma, Ewing’s sarcoma, other mesenchymal tumors. 3, other factors: nodal disease, sinus histiocytosis, vascular follicular hyperplasia (including Castleman’s disease, vascular lymphoid hyperplasia with eosinophils, i.e. Kimura disease and related diseases) Lymph nodes are found throughout the body and can only be palpated in more superficial areas; lymph nodes located in the neck, submandibular, supraclavicular fossa, axilla and groin are the most easily palpable. When the lymph nodes are enlarged, round, oval or striated nodules can be palpated under the skin. If swollen lymph nodes are palpated under the jaw, they mostly indicate oral lesions, such as tonsillitis, periodontitis, pulpitis or periapical inflammation. The appearance of bunches of bulbous bulges in the neck should first be considered as cervical lymphatic tuberculosis. Patients with nasopharyngeal carcinoma often have swollen lymph nodes on the deep neck. Enlarged lymph nodes in the armpit often suggest upper limb or breast disorders. Swollen inguinal lymph nodes are a sign of infectious diseases in the lower limbs and buttocks. In addition, one should not ignore the pathological reaction of lymph nodes caused by uterine cancer, testicular cancer, and rectal cancer. Enlarged left supraclavicular lymph nodes mostly indicate cancer cells in the abdominal cavity metastasizing upward along the thoracic duct, such as liver cancer, stomach cancer, colon cancer, etc.; enlarged right supraclavicular lymph nodes indicate cancer cells in the thoracic cavity metastasizing upward along the right lymphatic duct, such as lung cancer, esophageal cancer, etc. In lymphatic leukemia, all lymph nodes in the body show enlargement. Judging from the clinical manifestations, lymph node metastatic cancer is seen at the oldest age, with no gender difference, more frequent disease duration and larger lymph nodes. Lymphatic tuberculosis is more common in women and has a longer course. Patients with lymphadenopathy were mostly younger, with a shorter average disease duration and smaller lymph nodes. Malignant lymphoma is more common in men than women, with marked lymph node enlargement and often associated with fever. Lymph node reactive hyperplasia is multisite, often with fever, and has a shorter average disease duration. Histiocytic necrotizing lymphadenitis (Kikuchi disease) has a young age of onset with high fever and marked lymph node swelling and pain. The diagnosis of neck masses is 80% regular as a reference for diagnostic analysis: 20% of non-thyroidal tumors of the neck are inflammatory, malformations or other non-neoplastic diseases; 20% of malignant tumors are primary tumors of the neck and 80% are metastatic tumors; 20% of metastatic tumors originate from the thoracic and abdominal organs and 80% from malignant tumors of the head and neck. Among the metastatic malignant tumors, 20% of the primary foci are unknown and 80% can be found. Notably, the number of cases diagnosed as reactiveproliferationofthelymphnode in the neck has increased in recent years. It is often an unexplained enlargement of lymph nodes in multiple locations with no or mild discomfort. There are various factors that can cause reactive proliferation of the lymph nodes, such as viruses, certain chemical drugs, toxic products of metabolism, degenerated tissues and foreign bodies. Histologically, lymph node reactive hyperplasia has a complex presentation and is a lymphoid junctional lesion between benign and malignant. If there is atypical hyperplasia of lymphoid tissue, it is necessary to pay attention to the malignant tendency and be closely observed. It is important to know the nature of lymph node enlargement for the diagnosis of the disease. In case of acute and chronic inflammation, the lymph nodes are soft and movable, with no adhesion to the surrounding tissues and skin, with free sensation, and typical symptoms such as redness, swelling, heat and pain in the acute stage. In case of lymphatic tuberculosis, the lymph nodes do not adhere to the skin and surrounding tissues in the early stage, and after the condition worsens, the lymph nodes may continue to swell, but generally do not exceed the size of a walnut, and later they may adhere and fuse into pieces, liquefy, break down, and flow out brownish yellow pus or cheese-like material. The enlarged lymph nodes caused by cancer are mostly hard and stone-like, with uneven surface, and may adhere to the skin without pain or pressure. In case of lymphoid leukemia, the enlarged lymph nodes are usually movable, non-adhesive, smooth, not hard, not painful, and not septic and ruptured. Depending on the location of the enlarged lymph nodes, the primary lesion causing the enlarged lymph nodes can be generally understood. However, special examinations such as X-ray, pathology microscopy, ultrasound, CT and immunohistochemistry should be performed when necessary.