Pulmonary metastatic giant cell tumors presenting as totally hyalinized and ossified nodules.

We report a case of giant cell tumor of the left distal femur with simultaneous bilateral pulmonary metastases. Pathologic examination of the left lung nodule showed a metastatic giant cell tumor with a noncontinuous ossified rim, and the right lung nodules were totally hyalinized or ossified without residual giant cell tumor components. Hyalinization was a consistent finding in both the primary bone lesion and the pulmonary metastases. Because the patient did not receive chemotherapy or radiotherapy before her surgical procedure, we believe that these changes represent spontaneous tumor regression.