Ultrasonography can correctly estimate the location, scope and size of the tumor and indicate whether the soft tissue mass destroys the bone cortex or not, which is very important for the diagnosis of soft tissue tumors, especially for the masses adjacent to the joints, which is of greater significance. Ultrasonography can be used to: 1) understand the size and depth of soft tissue mass; 2) understand whether the tumor is cystic or solid; 3) understand whether the tumor is rich in blood flow; 4) help to determine the benign and malignant nature of soft tissue tumor. Therefore, ultrasound is the most widely used examination tool in preoperative diagnosis and postoperative follow-up of soft tissue tumors. Doctor’s tip: Under normal physiological conditions, ultrasound is almost completely reflected on the surface of bone, and it is difficult to penetrate the bone tissue, so it is difficult to get the image of the deep surface of the bone, but in pathological conditions, due to the change of physical properties of bone tissue, ultrasound can be partially penetrated, which makes the diagnosis of bone diseases, including tumors, possible.