Clinical and immunohistochemical characteristics of benign giant cell tumour of bone with pulmonary metastases: case series.

PURPOSE. Giant cell tumour of bone with pulmonary metastases is rare. However, some patients die of pulmonary metastases, and histological examination cannot distinguish between benign tumour and malignant metastases. In this study, we present clinical and immunohistochemical findings associated with giant cell tumour of bone with pulmonary metastases. METHODS. Five patients with benign giant cell tumour of bone with pulmonary metastases (one man and 4 women) were studied. Patients' ages ranged between 20 and 23 years (mean age, 21.8 years). Tumours were in the distal femur in 2 cases, and in the proximal tibia, distal tibia, and lumbar spine in one case each. The tissue specimens from primary tumours, recurrent tumours, and pulmonary metastases were studied using immunohistochemical techniques. RESULTS. Three of the 5 primary tumours were of the spontaneous regression or growth cessation type, or the continuously slow-growing type, showing 4.2% to 6.2% of positive cells for Ki-67 after immunohistochemical staining. However, 2 patients with the rapid-growing type of disease died of pulmonary metastases; their primary, recurrent, and metastatic tumour specimens contained 9.0% to 11.5% of positive cells for Ki-67. CONCLUSION. Three of the 5 primary tumours had a benign clinical pattern and immunohistochemistry. Two of the 5 patients died of pulmonary metastases, which had an aggressive clinical pattern and a high prevalence of positive cells in Ki-67. Examination of Ki-67 should be carried out for aggressive type of giant cell tumour.