Chondrosarcoma
Chondrosarcoma (CHS) represents 20-30 % of all malignant bone neoplasms and is the second most common solid malignant tumor of bone after ostegosarcoma. CHS is classifi ed as primary or secondary if the tumor arises de novo or develops in a preexisting benign cartilage neoplasm (enchondroma or osteochondroma), respectively. By the same token, CHS is classifi ed according to its anatomic location within a bone as central when it is located in the medullary cavity of a long bone (80-85 % of cases) or peripheral (about 10-15 of cases) or juxtacortical or periosteal when the tumor is located on the surface of a bone (1 of cases). Microscopically, CHS is a group of different clinicopathological entities in which the common denominator is the presence of hyaline cartilage. The most common is the primary or conventional CHS that represents 85 % of all the CHSs and is a tumor composed predominantly of hyaline cartilage in various stages of differentiation. Its variants include a specifi c cell component such as a high-grade sarcoma component in dedifferentiated CHS, clear cells in clear-cell CHS, and a small-cell component in mesenchymal CHS. Each one of these subtypes has distinct clinical, radiological, histological, and genetic features. Secondary chondrosarcoma may arise in a sporadic osteochondroma, in a genetic syndrome characterized by multiple osteochondromas (hereditary multiple exostosis), or in skeletal enchondromatosis (Ollier or Maffucci diseases). The prognosis of CHS depends on the histological grade, stage, and location of the tumor. According to the National Cancer Data Base Report, the relative 5-year survival rate of CHS is approximately 75 %, and patients who survive the fi rst 10 years after diagnosis of conventional CHS will die of other causes rather than from CHS-related events. High-grade (grade 3) conventional CHS and dedifferentiated and mesenchymal CHSs account for those cases with less favorable prognosis.
