As a common bone tumor, the combination of clinical manifestations, imaging examination and pathology is the main diagnostic basis of GCTB, and surgical treatment is still its first choice. Campanacci stage is the key factor affecting the recurrence, and appropriate surgical procedures should be selected according to different Campanacci stages. The criteria of Campanacci stage are as follows: stage I, the tumor does not involve the bone cortex; stage II, the tumor invades the bone cortex but does not penetrate the cortex. stage III, the tumor penetrates bone and extends into soft tissue [3]. The higher Campanacci stage and the smaller mean area of subchondral bone, the more inclined surgical method is extensive excision and prosthesis reconstruction, otherwise, the curettage of the lesion should be chosen as far as possible.
For giant cell tumors of the pelvis, sacrum and spine, neoadjuvant therapy with denosumab is required in most cases due to the large size of the tumor at the time of diagnosis and its proximity to important organs and tissues. Denosumab can inhibits osteoclast, promotes new bone formation, and harden the boundary of lesion [4–5]. Preoperative desumumab neoadjuvant therapy can effectively reduce the tumor volume, make the tumor boundary clearer, reduce the blood supply to the lesion site, reduce the difficulty of surgery, and thus reduce the tumor staging and recurrence rate [6].
Sometimes GCTB near the articular surface also be treated with denosumab neoadjuvant therapy in order to preserve the articular surface as much as possible. Unlike the pelvis and sacrum, GCTB in the extremities are generally not very large because most tumors have already been controlled by surgery or other treatment at the time of pain or finding the mass.
The patient in this case had a rare large tumor that broke through the bone cortex and involved surrounding soft tissues, joint cavities, and fibular head. Due to the invasion of blood vessels, nerves and skin ulceration, the limb was not equipped with the condition of limb salvage. Preoperative chest CT showed multiple small nodules in the left lung, the largest of which was about 4mm in diameter. The postoperation positron emission tomography-computed tomography (PET-CT) indicated small nodules in the upper lobe of left lung and the lower lobe of right lung with no metabolism. The lung is the target organ for distant metastasis of GCTB. In this case, the onset time of this patient was long and the tumor volume was large, so special attention should be paid to the lung in the follow-up.