Giant cell tumor of bone (GCTB) is a rare, benign, but locally aggressive bone neoplasm with a predilection for young adults. It is characterized by an abundance of osteoclastic giant cells induced by neoplastic mononuclear cells, which express high levels of receptor activator of nuclear factor κ-B ligand (RANKL)
Risk factors
- Age and location: Younger patients and those with axial disease are at increased risk of pulmonary metastasis
- Disease stage and recurrence: Patients presenting with Enneking stage-3 disease or those who develop local recurrence are also at increased risk of pulmonary metastasis
Prognosis
- Recurrence and metastasis: The recurrence rate of GCTB is similar to that of solitary giant cell tumors. Metastatic disease can develop, and malignant transformation is possible
- Telomerase activity: The activity of the telomerase enzyme complex correlates with recurrence in GCTB. Positive telomerase reverse transcriptase immunohistochemistry correlates with shorter recurrence-free survival
Pathophysiology
- Genetic mutations: GCTB is genetically characterized by highly recurrent and specific mutations of the H3F3A gene, which encodes histone H3.3
- Cellular composition: Histologically, GCTB is composed of histiocytoid to spindled mononuclear cells, admixed with numerous large osteoclastic giant cells
Clinical manifestations
- Symptoms: Patients may present with pain, swelling, and limited range of motion in the affected area.
- Radiographic findings: Radiographically, the tumors in long bones manifest as expansive lytic lesions involving the metaphysis and extending into the epiphysis
In conclusion, GCTB is a rare, benign, but locally aggressive bone neoplasm with a predilection for young adults. It is characterized by specific genetic mutations and a unique cellular composition. The prognosis of GCTB is influenced by factors such as age, disease stage, and recurrence. The clinical manifestations of GCTB include pain, swelling, and limited range of motion, with radiographic findings of expansive lytic lesions.