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disturbance, cranial neuropathies, hearing loss and disturbances of gait. Imaging shows mottled calcification within the soft tissue mass on CT scanning.

Chondrosarcoma tends to act less aggressively than other sarcomas but nevertheless pursues a slow and intractably progressive course, which ultimately kills the patient in many cases. The history therefore tends to be long and is punctuated by multiple local recurrences. Distant metastases are relatively rare, occurring in only about 8% of cases [6].

Surgery is the primary treatment modality. Conventional radiotherapy has been used as an adjunct. More recently, some workers have advocated proton beam radiation therapy as the adjuvant radiation modality of choice. This form of irradiation is of interest to the radiation oncologist because of its improved dose localization capabilities in comparison to high-energy X-rays (photons). It is suggested [7] that proton radiation therapy after maximal surgical resection represents the best management policy currently available for patients with chondrosarcomas (and chordomas) of the skull base.

Chordoma

These are slow-growing, locally aggressive malignant neoplasms, derived from vestigial remnants of the notochord found along the axial skeleton. They account for less than 1% of all intracranial neoplasms [8]. They can be divided into three main groups, depending upon the site of origin: cranial (35%), sacrococcygeal (50%) or vertebral (15%). Cranial lesions tend to affect a younger age group (range 20-40 years) compared to the sacrococcygeal group (40-60 years). Men are more commonly affected than women (3:1).

The location of a chordoma within the clivus determines the nature and path of its growth, the associated anatomic structures involved, the clinical symptomatology, and the approach for surgical management. However, whatever their position within the clivus and their symptoms, presentation is usually late after intracranial extension has occurred.

Lesions arising near the inferior tip of the clivus, the basion, usually produce lower brain stem compression as they expand and present clinically with hypoglossal nerve lesions. Tumors arising from the body of the clivus are the most common. They may expand ventrally and produce a nasopharyngeal mass with obstruction, or they may expand dorsally and stretch the sixth cranial nerve as it runs along and penetrates the clival dura, leading to diplopia. Tumors arising at the rostral end of the clivus involve the sella turcica and may present with hypopituitarism. With suprasellar extension, a chiasmal syndrome with bitemporal hemianopia may result. Lateral extension of rostral clival chordomas may produce a parasel-lar mass or extend into the cavernous sinus, affecting cranial nerves III—VI. Postero-lateral extension of mid-clival chordomas can produce otologic symptoms of deafness, vertigo and tinnitus, with risk of facial weakness through involvement of the petrous temporal bone.

The position of the tumor rarely allows complete surgical resection and thus recurrence rate after surgery remains high. In view of the high local recurrence rate, conventional radiotherapy has been used, with varying success. As mentioned above, it is suggested that proton radiation therapy after maximal surgical resection seems to represent the best management policy currently available for patients with chordomas of the skull base.

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