Rare case of malignant transformation of a solitary spinal osteochondroma into recurrent metastatic chondrosarcoma

Abstract Osteochondroma or osteocartilaginous exostosis is a commonly occurring primary tumor of the bone. Solitary spinal osteochondromas are, however, very rare, seen in only in 1–4% of all known cases and only few symptomatic cases have been reported in the literature so far. Further, while recurrence and malignant transformation are known to occur in osteochondroma, this is rare in the spine. We would like to report one such a case of an unusual presentation of recurrent, metastatic spinal chondrosarcoma in a patient with previous history of solitary cervical osteochondroma.