There is a very large heterogeneous density intracranial mass lesion is mostly of fluid attenuation with areas of calcification and fat density demonstrates a rim of smooth post-contrast enhancement. The lesion results in 15 mm of left-to-right midline shift and marked mass effect with distortion of the left lateral ventricle and effacement of the third ventricle leading to obstructive hydrocephalus of the right lateral ventricle as well as left uncal herniation, but no tonsillar herniation. There is also periventricular interstitial oedema, consistent with acute hydrocephalus. There are pockets of fat density surrounding the mass, particularly anteriorly, and the lesion probably arises from the skull vault in the region of the junction of the left frontal and temporal bones with growth inwards. No acute displaced skull fracture. There is mild mucosal thickening in the ethmoid air cells. The other visualised paranasal sinuses, mastoid air cells and middle ear clefts are well-aerated.
Conclusion: Large fat-containing intracranial mass lesion with surrounding fat density, probably arising from the skull vault likely represents a large dermoid/epidermoid.