Cytofluorometric DNA ploidy analysis in giant cell tumor of bone: histologic and prognostic value

DNA ploidy analysis by DNA cytofluorometry was performed on 41 tumors obtained from 37 patients with primary giant cell tumor of bone (GCT). Histologically, 26 of the tumors from primary or recurrent lesions were evaluated as grade I, and 13 tumors as grade II. Among the 33 primary GCT patients, 4 patients had local recurrence or pulmonary metastasis. The DNA ploidy pattern and the percentage of hyperdiploid cells showing a greater DNA content than diploid cells, were obtained from DNA cytofluorometry. All of the 33 primary tumors were diploid. Of 6 recurrent tumors, 4 were diploid and 2 were euploid–polyploid. One of the two pulmonary metastatic tumors was diploid, but another that demonstrated a malignant transformation to malignant fibrous histiocytoma was aneuploid. The percentage of hyperdiploid cells was significantly different between primary and recurrent tumors (P=0.0188) and between grade I and grade II tumors (P=0.0052), while there was no difference between primary tumors in the cases that recurred or metastasized and those that did not. Thus, these data indicate that cell proliferative activity is closely correlated with biological aggressiveness and histological grading, although DNA ploidy is not useful for predicting prognosis.