A case of probable benign pulmonary "metastases" or implants arising from a giant cell tumor of bone.

Several large pulmonary lesions were found in a 45-year-old woman after therapy for a typical tibial giant cell tumor. The pulmonary lesions were incidentally found during a routine chest examination four years after the original bone tumor had been found. Removal of the lung lesions showed ordinary giant cell tumor identical to the primary bone tumor, with no evidence of sarcomatous transformation. After an analysis of 12 other well-documented cases in the world literature, we postulate that the lung lesions in this case probably represent benign "metastases;" i.e., benign tumor implants compatable with a good long-term prognosis, rather than the usual lethal course associated with the vast majority of metastatic malignancies.