Dedifferentiated chondrosarcoma of the cervical spine in a patient with multiple osteochondromas

Dedifferentiated chondrosarcoma (DCS) is a biphasic tumor, comprising a low-grade chondrosarcoma juxtaposed to an anaplastic sarcoma with a high degree of malignancy. DCS of the spine arising from osteochondromas is extremely rare. We report a very unusual case of a 28-year-old female with DCS originating from a cervical spine osteochondroma. At the age of 12 the patient was diagnosed as having multiple osteochondromas. At the age of 28, she consulted our clinic complaining of rapid increase of the mass and dull pain. Radiological examination revealed a 12 cm x 8 cm sized mass with irregular calcification and cauliflower-like surface, arising from the second to the sixth cervical spines. The tumor was removed with the suspicion of secondary chondrosarcoma arising from the predisposing osteochondroma of the spine. Histological examination revealed the tumor was composed of a biphasic pattern, one with well differentiated chondrosarcoma and the other with high grade spindle cell sarcoma (malignant fibrous histiocytoma). The tumor was diagnosed as DCS in the spine. The patient died of pulmonary metastasis at 6 years after surgery.