Some parents mistakenly think that the swelling and pain is caused by an injury, and some parents mistake it for growing pains and do not take it seriously. Only when the child is unable to walk on the ground do they go to a regular hospital, but unfortunately the condition is already very serious. In my practice, I often encounter such cases, and recently I have met three such patients. One was a seven-year-old boy and the other was a teenager in high school. Both of them thought that they had injured their knee joints at school and did not go to the orthopedic department of the hospital. The individual has already metastasized, as parents already regret too late. 1, no obvious reason for swelling and pain in the knee joint, the back of the hand is hotter to touch than the opposite side, the skin surface seems to have angry veins, and the lump is felt. 2. X-rays showing periosteal reaction with bone cortical destruction need further CT, MRT examination.