Specific Imaging Findings

The characteristic appearance of chondrosarcoma is a mass eroding the petro-clival junction. These tumors show low to intermediate T1 signal and predominantly very bright T2 signal. Heterogenous appearance is frequent with areas of signal loss on T2-weighted images (sometimes along with T1 hyperintensity), caused by matrix mineralization and/or fibrocartilaginous elements. The matrix mineralization with whirls of calcifications represents a very characteristic CT finding, but this is present in less than half of the cases. These tumors are also bright on ADC maps, reflecting very high diffusion. Chondrosarcomas show variable intensity of post-contrast enhancement, usually in a heterogeneous fashion with linear and nodular areas. Distinction from chordomas is not reliable. In rare cases chondrosarcomas may arise at unusual locations, such as the jugular foramen or from the dura of the falx.

Pertinent Clinical Information

Chondrosarcomas are uncommon locally aggressive skull base tumors, which most commonly occur in young patients (on average in the third decade of life) with diplopia (commonly caused by the abducens nerve palsy) and headaches being the most common presenting symptoms. These are generally low-grade tumors, with gradual and slow onset of symptoms, usually with a protracted course before the diagnosis is made. Both CT and MRI are usually necessary for complete evaluation due to the involvement of both soft tissue and bony structures at the skull base. Chondrosarcomas occur at a higher frequency in patients with Ollier's disease and Maffucci's syndrome.