Multicentric giant cell tumor of bone: Clinicopathologic analysis of thirty cases

Background: Giant cell tumor of bone accounts for 4% to 5% of primary bone tumors. Approximately 1% of cases present as multiple synchronous or metachronous lesions. In this study, we describe the clinicopathologic features of thirty cases of multicentric giant cell tumor. Methods: Thirty patients who had two or more separate lesions that had been pathologically confirmed to be giant cell tumors were identified. Radiographs were reviewed to evaluate the characteristics and locations of the tumors. Histologic reexamination was performed to document morphologic features. Clinical information and follow-up data were obtained from the medical records. Results: The male:female ratio was 1:2, with an average age at presentation of twenty-one years. Fifty-nine percent of the patients were younger than twenty years of age. There were ninety-four tumors in the series, with an average of three (range, two to nine) per patient. Most tumors had arisen in the long bones. Six patients had synchronous ipsilateral involvement of the distal part of the femur and the proximal part of the tibia. Radiographically, the tumors in long bones manifested as expansive lytic lesions involving the metaphysis and extending into the epiphysis. A minority of the tumors were confined to the metaphysis, had features of a fibro-osseous or bone-forming lesion, or arose in skeletally immature patients. Secondary histopathologic changes including fibrohistiocytic regions, reactive bone formation, or aneurysmal bone cyst-like changes were not uncommon. Most tumors were treated with curettage (64%) or resection (22%). The recurrence rate was similar to that of solitary giant cell tumors. Metastatic disease developed in three patients, and two patients had malignant transformation. Conclusions: Multicentric giant cell tumors occur more often in younger patients than do solitary giant cell tumors, and they frequently present as synchronous lesions around the knee. Some tumors appear as bone-forming or fibroosseous tumors on imaging studies as a result of fibrohistiocytic regions and reactive bone formation. The risk of recurrence depends on the type of surgery that is performed. Level of Evidence: Therapeutic Level IV.