ABSTRACT
<p><b>OBJECTIVE</b>To study the histogenesis of giant cell tumor (GCT) and factors related to tumor recurrence, invasiveness and malignant transformation.</p><p><b>METHODS</b>The clinical features, radiologic classification, surgical approach, pathologic findings, immunophenotypes and follow-up data of 123 cases of GCT were analyzed.</p><p><b>RESULTS</b>There was a significant correlation between tumor recurrence and radiographic classification (P = 0.032), over-expression of CD147 (P = 0.034) and p53 (P = 0.005), and surgical approach (P = 0.0048) in GCT. The biologic behavior showed no correlation with intramedullary infiltration, cortical bone involvement, parosteal soft tissue extension, tumor thrombi, fusiform changes of mononuclear tumor cells, mitotic count, Ki-67 index, coagulative tumor necrosis, secondary aneurysmal bone cyst formation, and adjoining bony reaction. The positive rate of p63 in stromal cells of GCT (79.7%, 94/118) was significantly higher than that in chondroblastoma (44.7%, 21/47), osteosarcoma (22.2%, 10/45) and other giant cell-rich tumors.</p><p><b>CONCLUSIONS</b>GCT is a bone tumor of low malignant potential. It is sometimes characterized by locally invasive growth, active proliferation, coagulative necrosis, secondary aneurysmal bone cyst and surrounding bony reaction. It is difficult to predict the biologic behavior of GCT. Over-expression of p53 in the tumor cells and CD147 in all components of GCT correlate with tumor invasiveness, recurrence and malignant transformation. Selection of suitable surgical approach with reference to radiologic classification is considered as an important factor in reducing the recurrence rate.</p>