Radiodiagnosis of intracranial pearly tumours with particular reference to the value of computer tomography.

The radiological appearances of 22 histologically proven epidermoid and dermoid tumours occurring in four sites are presented - (1) the petrous apex and cerebellopontine angle, (2) the suprasellar region, (3) the cerebral hemispheres and (4) the cerebellum and 4th ventricle. Pathognomonic radiological changes are only uncommonly demonstrated by conventional neuroradiological techniques. Computer assisted tomography employing an EMI scanner has demonstrated diagnostic appearances. The availability of detailed density changes occurring within the tumours together with additional intracranial information makes computer tomography the investigation of choice.