The main clinical causes of swollen lymph nodes are as follows. Acute inflammatory infections in the body, such as patients with acute mastitis can cause swollen axillary lymph nodes, and patients with acute purulent tonsillitis can cause swollen submandibular lymph nodes. The swollen lymph nodes caused by acute inflammation can usually subside on their own after the primary infection is controlled, and the painful symptoms can be gradually relieved, so the prognosis is relatively good and will not cause serious complications. Secondly, malignant tumor invasion causes lymph node enlargement, for example, malignant tumor of liver invades to the hepatic hilum and causes lymph node enlargement at the hepatic hilum. Malignant tumor of rectum invades to the inferior mesenteric artery and causes lymph node enlargement at the inferior mesenteric artery. Lymph node enlargement caused by malignant tumor indicates that the patient’s condition is advanced. Even if the primary tumor and lymph nodes are resected intraoperatively, the probability of recurrence is still high after surgery, and the prognosis is relatively poor.