NeuroradiologyChondroma, intracranial
benign slow-growing tumours that may be found in any part of the body. Intracranially they account for less than 1% of tumours and can arise from the skull base, from the dura, from the brain
parenchyma, or within the ventricles. The true cause is unknown. They have been reported to arise at sites of previous
trauma and in association with systemic chondromatoses such as Ollier's disease and Mafucci's syndrome. Skull base chondromas usually remain extradural and are presumed to arise from embryonic
cartilage rests along the basilar synchondroses. Of the small number of intraparenchymal chondromas, only a few are truly parenchymal and reportedly arise by metaplasia in an existing glioma. The remainder are intraventricular and are usually associated with choroid plexus. Chondromas of dural and choroid plexus origin may arise as a result of metaplasia of arachnoid elements in that their location within the cranium is similar to that of meningiomas.
Intracranial chondromas have been reported in patients ranging from 15 months to 60 years of age, with a peak incidence in the third decade and no preference for either sex.
Imaging
On CT, chondromas can be hyperdense or hypodense relative to brain. Contrast enhancement is usually minimal and can be evident within the substance of the tumour.
On MR imaging, the tumour shows hypointense signal on T1-weighted images and mixed hypointense and hyperintense signal on T2-weighted images. A rim of enhancement as well as minimal enhancement within the lesion may be shown with infusion of contrast material. Angiography demonstrates a vascular mass displacing adjacent cortical vessels. No tendency is shown towards invasion or destruction of the surrounding parenchyma and there is little tendency for sarcomatous change. Total excision is frequently possible and is curative, with no recurrence reported on long-term follow-up.
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