Aggressive clinical course of giant cell tumor arising from thoracic vertebra after a long latent period.

We report the aggressive clinical course of a giant cell tumor (GCT) arising from thoracic vertebra after slow growth for 7 years without treatment. GCTs of bone usually have the characteristics of local recurrence and a low potential for distant metastasis. The patient was a 37-year-old man with an unresectable large tumor of the mediastinum. The histopathological diagnosis of a biopsy specimen was GCT. He had received no treatment for 7 years after the initial diagnosis because the growth rate of the tumor was very slow. However, the tumor at the primary site then rapidly increased in size, and numerous multiple bone metastases developed despite radiotherapy for the primary tumor. These aggressive bone metastases with small numerous radiolucent lesions are rare.