[Giant cell tumor of bone and malignancies in giant cell tumor: a clinicopathologic analysis]

To study the clinicopathologic features, diagnosis and differential diagnosis of malignancies in giant cell tumor (MGCT).

The clinicopathologic features of 13 cases of MGCT were retrospectively reviewed.

Thirteen cases of MGCT were found amongst a total of 603 cases of giant cell tumor encountered. Six of the 13 cases represented concurrent malignancy in giant cell tumor while the remaining 7 cases was malignant transformation in recurrent giant cell tumor. The age of the patients ranged from 21 to 71 years (mean age = 39.5 years) in the first group and from 27 to 52 years (mean age = 36.7 years) in the second group. In concurrent MGCT, a high-grade sarcoma component was present in conjunction with the giant cell tumor component. In malignant transformation of recurrent giant cell tumor, the original tumor was giant cell tumor and the recurrence showed features reminiscent of malignant fibrous histiocytoma.

The diagnosis of malignancies in giant cell tumor requires correlation of clinical, radiologic and pathologic features. The entities need to be distinguished from other giant cell-rich tumors including primary malignant fibrous histiocytoma and giant cell osteosarcoma.