| disease | Giant Cell Tumor of Bone |
Giant cell tumor of bone is one of the more common primary bone tumors in our country. This tumor grows aggressively and causes significant bone erosion and destruction. Without timely and proper treatment, it can lead to severe disability and even necessitate amputation. In a few cases, metastasis may occur, which can be fatal. The tumor tissue is highly vascularized, soft, and fragile, resembling granulation tissue, and is prone to bleeding. It contains areas of fibrous organization and hemorrhage. The cellular composition includes round cells and spindle cells (i.e., stromal cells), interspersed with larger gaps showing signs of hemorrhage. Numerous giant multinucleated cells (with 10 to 200 nuclei) are present. The bone cortex becomes thin, and sometimes the tumor penetrates the cortex, extending into soft tissues. Biopsy specimens should include all parts of the tumor. Currently, there is a tendency to consider stromal cells as the main parenchymal cells of this tumor.
bubble_chart Diagnosis
There is often only dull pain or stabbing pain, intermittent in nature, with possible localized swelling. Due to its insidious progression, some tumors have already grown to a considerable size by the time patients seek medical attention. The lesions frequently occur at the ends of long bones, which may restrict the movement of nearby joints.
Eighty percent of cases occur after the age of 20, rarely before the closure of the epiphyseal plate. Only 3.5% occur in individuals under 15 years old, and cases over 50 are also uncommon. The highest incidence is between 20 and 40 years of age. Benign giant cell tumors are more common in women than in men, with a ratio of about 3:1, whereas malignant ones are more common in men, also at a ratio of approximately 3:1.
Seventy-five percent of tumors are located at the ends of long tubular bones, with 50% occurring near the knee joint—specifically, the distal femur and proximal tibia/fibula. The distal radius and proximal humerus are also common sites. A few cases are found in the pelvis and vertebrae, with rare reports of multiple occurrences.**X-ray Findings** The characteristic X-ray features of this disease aid in early diagnosis. The hallmark is focal osteolytic destruction of bone tissue. In the epiphyseal region of long tubular bones, a large, eccentric radiolucent area is visible. The lesion's margins are clear, with fine or coarse trabeculae traversing the area—these trabeculae do not represent new bone formation but rather the walls of the destroyed epiphysis. The tumor may extend to the articular cartilage and even cause intra-articular fractures. On the affected side, the bone cortex is notably expanded and thinned, with generally no periosteal new bone formation externally. Sometimes, the appearance is multicystic or soap-bubble-like. Some large, expansive tumors may involve the metaphysis or occupy the entire epiphysis, bordered by a thin, sclerotic layer caused by shrinkage of the expanded inner cortex or minimal peripheral reactive bone formation. Rarely, a typical periosteal reaction such as Codman's triangle may form. As the tumor grows, the periosteum may appear exfoliated. If the bone cortex at the tumor site ruptures and periosteal new bone formation increases, these signs may suggest malignant transformation.
**﹝Auxiliary Examinations﹞**
**X-ray Findings:** A localized cystic change is observed in the epiphysis, typically showing osteolytic destruction or a "soap-bubble" appearance. Expansion is usually limited by cartilage and does not invade the joint. Periosteal reaction is rare, and the tumor boundaries are clear. Initially, the lesion is located on the lateral side within the epiphysis but may eventually occupy the entire bone end, with the cortex becoming expanded and thinned. In some cases, it may perforate and extend into soft tissues. While X-rays can reveal general characteristics, they are insufficient for a definitive diagnosis.
Based on the natural history of this disease. Hutter et al. pointed out that approximately 30% of curettage cases recur within 2 years, and 50% recur within 5 years. All recurrent cases, 90% occur within 5 years. Therefore, local recurrences after 5 years should be considered as potentially malignant transformations. They reported that only one-third of cases were cured after a single surgery, another one-third were cured after two surgeries, and the remaining one-third required 3 to 5 surgeries to achieve complete eradication.
Thus, if the goal is to achieve cure with a single surgery, radical surgery must be performed, which involves the thorough removal of the tumor, including en bloc resection with an adequate margin of normal tissue. According to Thompson’s report, the recurrence rate after thorough curettage and bone grafting was 29.6% in the first year, rising to 54.1% by the fifth year, and approximately 10% of giant cell tumors of bone undergo malignant transformation. This also indicates that curettage and bone grafting are not suitable for most giant cell tumors of bone. For giant cell tumors in the trunk bones, the prognosis after curettage and bone grafting is better than for those in the limb bones. For cases with repeated recurrences after curettage and suspected malignant transformation, segmental resection should be considered. Segmental resection can be combined with arthrodesis, hemiarthroplasty, or prosthetic reconstruction.
For primary malignant giant cell tumors or malignant transformed fleshy tumors, amputation is required. Amputation should also be considered when the tumor involves a wide area or has invaded soft tissues, making limb function reconstruction difficult after segmental resection or when radical treatment cannot be achieved.
