A Clinicopathologic Study of 33 Cases of Benign Giant Cell Tumor of Bone.

Thirty-three cases of benign giant cell tumor of bone were analyzed clinicopathologically. The most common site of the tumor was around the knee. At the time of diagnosis, patients ranged in age from 20 to 74 years (mean 36.3 years). Nine patients had had local recurrences.One patient has had multiple pulmonary metastases one and half years after his initial surgery of curettage and packing with methylmetacrylate. The pulmonary lesion was confirmed by thoracoscopical biopsy as a metastatic giant cell tumor. The patient remains well and working without any symptoms one year after metastases. The lesions show no change in size and number.One of the most challenging differential diagnoses is the solid variant of aneurysmal bone cyst (SABC) or giant cell reparative granuloma.We compared giant cell tumors and a case of SABC roentgenologically and histologically. Focal aggregates of giant cells were present in both conditions in a similar fashion. X-rays and histology do not differentiate these lesions. Clinicopathologically, in some cases, a distinct differentiation of each lesion was impossible. We prefer the diagnosis of giant cell tumor rather than SABC when the lesion occurs in long bones and co-exists with dense aggregates of giant cells in small portions, even though in large areas the distribution of giant cells may be sparse.