approximately 90% of chondrosarcomas are histologically of the conventional type; in addition to conventional chondrosarcoma, some rare variants with distinctive microscopic and clinical features are discerned: clear cell chondrosarcoma (1%), mesenchymal chondrosarcoma (2%), juxtacortical chondrosarcoma (2%) and extra-skeletal myxoid chondrosarcoma (5%). Furthermore, dedifferentiated chondrosarcoma is a relatively rare high grade sarcoma next to a low-grade conventional malignant cartilage-forming tumor, comprising 6-10% of all chondrosarcomas. Conventional chondrosarcomas can be categorized according to their location in bone. The majority of chondrosarcomas (75%) are located centrally within the medullary cavity (central chondrosarcoma), a small percentage of which arise within a preexisting benign precursor (enchondroma). While most enchondromas are solitary, patients with Olliers disease and Maffuccis syndrome demonstrate multiple enchondromas.A minority (15%) of chondrosarcomas develops from the surface of bone (peripheral chondrosarcoma) as a result of malignant transformation within the cartilaginous cap of a solitary or hereditary pre-existent osteochondroma.

primary malignant bone tumours occur 1/100,000, of which 17-24% consists of chondrosarcoma; the majority of patients are between 35 and 60 years old with equal sex distribution

compared to benign cartilaginous tumours, chondrosarcomas more frequently present with pain and tenderness; they usually develop in the trunk, pelvis and long bones.

There are no apparent cytonuclear differences between central and peripheral conventional chondrosarcomas and both are histologically classified into three grades using the criteria of Evans et al.

Grade I chondrosarcomas demonstrate low cellularity, limited cytonuclear atypia, few multinucleated cells, a mainly chondroid matrix and the absence of mitoses;

Grade II chondrosarcomas demonstrate increased cellularity, and increased muco-myxoid degeneration of the matrix. There is moderate cytonuclear atypia and occasional mitoses are found.

Grade III chondrosarcomas are highly cellular, with nuclear polymorphism, mitoses and a mostly myxoid matrix;

Increasing histological grade is correlated with higher metastatic potential; it is considered difficult to assess the histological grade of cartilaginous tumours and to reliably distinguish between benign tumours and those of low-grade malignancy.

because chondrosarcoma is highly resistant to chemotherapy and radiotherapy, surgical treatment is the only option for curative treatment

the majority of central chondrosarcomas are considered to arise de novo and malignant transformation of solitary enchondroma is extremely rare (

metastasis in chondrosarcoma highly depends on the histological grade of malignancy; grade I chondrosarcomas demonstrate local recurrence, but seldom metastasize; grade II chondrosarcomas demonstrate metastases in 10-30% of the cases, whereas grade III chondrosarcomas demonstrate metasases in the majority of cases. In contrast to chondrosarcomas located elsewhere in the skeleton, those located in the phalanx behave as a locally aggressive lesion with minimal metastatic potential