bubble_chart Overview

Giant cell tumor of bone is one of the more common primary bone tumors in our country. This tumor grows actively and causes significant bone erosion and destruction. Without timely and proper treatment, it can lead to severe disability and even amputation, with a few cases metastasizing and becoming 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, along with numerous giant multinucleated cells (containing 10 to 200 nuclei). The bone cortex becomes thin and may sometimes perforate, extending into the 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 Clinical Manifestations

There is usually 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 often 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, with only 3.5% occurring under the age of 15, and cases over 50 being very rare. The most common age range is 20–40 years. Benign giant cell tumors are more common in women than men, with a ratio of about 3:1, while malignant cases are more common in men, also at a ratio of about 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 and fibula. The distal radius and proximal humerus are also common sites. A few cases occur in the pelvis and vertebrae, and there are occasional reports of multiple occurrences.

X-ray findings: The characteristic X-ray manifestations of this disease aid in early diagnosis. The hallmark feature is focal osteolytic destruction of bone tissue. In the epiphyseal region of long tubular bones, a large and eccentric radiolucent area can be observed; the lesion's margins are clear, with fine or coarse trabeculae traversing it. 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 markedly expanded and thinned, with generally no periosteal new bone formation outside the cortex. Sometimes, the appearance is multicystic or soap-bubble-like. Some large, expansive tumors may involve the metaphysis or occupy the entire epiphysis, with a thin, sclerotic boundary caused by shrinkage of the expanded inner cortex or minimal peripheral reactive new bone formation. Occasionally, typical periosteal reactions such as Codman’s triangle may form. As the tumor grows, the periosteum may appear exfoliated. If the bone cortex at the tumor site is ruptured and there is increased periosteal new bone formation, these signs may suggest malignant transformation.

bubble_chart Auxiliary Examination

X-ray findings: There is a localized cystic change at the epiphysis, usually presenting as osteolytic destruction, and sometimes exhibiting a "soap bubble" appearance. The expansion is generally limited by cartilage. It does not invade the joint, and there is minimal periosteal reaction. The tumor boundary is clear. Initially, the lesion is located at the lateral side of the epiphysis, and as it progresses, it may occupy the entire end of the bone. The cortical bone expands and thins, and in some cases, it may perforate and extend into the soft tissue. X-ray images can reveal these general characteristics, but they are still insufficient for a definitive diagnosis.

bubble_chart Treatment Measures

Based on the natural history of the disease, Hutter et al. pointed out that approximately 30% of curettage cases recur within 2 years, and 50% recur within 5 years. Among 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 radical cure.

Thus, to achieve a cure with a single surgery, radical surgery must be performed, which involves the complete resection of the tumor, including a wide excision with an adequate margin of normal tissue. Thorough curettage and bone grafting, according to Thompson's report, showed a recurrence rate of 29.6% after the first year, rising to 54.1% by the fifth year, with about 10% of giant cell tumors of bone transforming into malignancy. 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 for cases where the tumor involves a wide area or has invaded soft tissues, making limb function reconstruction difficult or radical cure unachievable after segmental resection.

Radiation therapy carries a higher risk of inducing fleshy tumor transformation and should be cautiously used only when surgery is unsuitable for certain anatomical locations.