Diagnosis by computerized tomography of intradural dermoid with spontaneous rupture of the cyst.

Two cases of para- and suprasellar dermoid cysts are presented. The specific CT findings for this tumour are demonstrated: very low absorption values below minus 40 EMI units, variable densities in the cyst content, shell-like annular calcifications, and absent central enhancement effect. Spontaneous perforation of the cyst with dissemination of dermoid material into the CSF spaces is shown. The differential diagnosis from other low density lesions (epidermoid, cystic craniopharyngioma, arachnoid cyst) is discussed.