The patient was a 45-year-old female with “swelling and pain in the left upper arm for 3 years.” She was admitted to the hospital. Physical examination: the proximal part of the left upper arm was obviously swollen, and a mass could be found, with hard texture, indistinct borders, no pulsation, normal skin temperature, normal sensation, muscle strength and reflexes of the left hand, normal reflexes of the left biceps muscle and radial membrane. Before admission to the hospital, he underwent X-ray examination of the left shoulder joint at the local hospital, which showed a bone tumor of the left proximal humerus. CT examination showed that the left upper humerus was an occupying lesion. The postoperative pathology showed: mucinous chondrosarcoma. The oncology department was asked to discuss and determine a comprehensive treatment plan, and “left proximal humeral tumor resection + shoulder joint prosthesis endoplasty” was performed under general anesthesia. The postoperative pathology showed: mesenchymal chondrosarcoma. The patient’s shoulder joint functioned well after the operation.