[Computed tomography of intracranial epidermoid cysts]

Diagnostic criteria of intracranial epidermoid cysts were established from the observation of 15 cases, confirmed by pathology, seen during the last 5 years. Tumors could be divided into four groups: posterior fossa, supratentorial spaces, transtentorial and extradural. Regions of hypodensity associated with the irregular nature of the outlines of the lesion are generally sufficient to suggest the diagnosis in a pre-operative scan, but certain tumors may be isodense or, more exceptionally, spontaneously hyperdense. Contrast images are extremely rare, and are seen only at the periphery of the lesions. The "mass-effect" is remarkably discrete when compared with the tumor size, sometimes of very large proportions.