Swollen lymph nodes in the leg fossa are not necessarily cancerous. Benign diseases such as knee osteoarthritis may also cause swollen lymph nodes in this area. However, inflammation-induced lymph node enlargement is often smaller lymph nodes that are movable and have a regular shape and are soft to the touch. If the lymph nodes are hard to the touch, the shape is not very regular, and they are fixed and cannot be pushed, it is highly suspected that they are malignant tumors. If the lymph nodes are suspected to be malignant, some of them need to be biopsied by puncture, or the whole lymph nodes can be cut down and sent to the pathology department for laboratory tests to determine whether they are malignant and what type of malignant tumor they are.