Metastatic chondroblastoma: report of an unusual case treated with radiotherapy.

Although most chondroblastomas are cured by limited surgical procedures, occasional lesions behave more aggressively and may even metastasize. We report here an unusual case of chondroblastoma, characterized by slow growth, two clinical recurrences following attempts at excision, and pulmonary metastases after a total course of 34 years. This tumor was moderately radiosensitive, as it decreased 50% in size 6 months after a dose of 4000 rads in 4 weeks. Review of the literature suggests that aggressive chondroblastomas may show several types of behavior. Most lesions are unusually aggressive from their inception, displaying local invasion and early recurrence. Other lesions, such as the present case, continue to grow slowly and may eventually metastasize if inadequately resected. This latter type of behavior may exemplify the natural history of untreated chondroblastoma.