Lymph nodes with unclear cortical and medullary demarcation may be enlarged due to tumor metastasis. Under normal circumstances, the corticomedullary demarcation of lymph nodes is very clear, and the lymph nodes are oval or broad bean shaped, with one end protruding and one end depressed. The depressed end is called the lymph node gate, which is also present under normal circumstances. If during ultrasound examination or CT or MRI examination, it is found that the lymph node morphology has changed from oval to round, and the lymph node gate disappears, and the dermal medulla also disappears, it means the possibility of tumor metastasis is very high. It is common for gastric cancer to show intra-tie lymph node metastasis, or colorectal tumor to cause intra-tie lymph node metastasis. During surgery, the lymph nodes in the region should be cleared, and if metastasis is suspected in a certain place before surgery, it should be cleared together during the surgery. After clearance, pathological examination is routinely performed, and the positive rate of lymph nodes needs to be determined.