Spectrum of intracranial and spinal epidermoids including unusual locations and imaging findings: A pictorial review.

Intracranial and spinal epidermoids are benign slow-growing congenital lesions. They are predominantly intradural, extra-axial in location, with intra-axial locations (intra-parenchymal and spinal intramedullary) being rare. The most common locations of intradural epidermoids are cerebellopontine angle cistern followed by supra- and para-sellar regions, and fourth ventricle. Less common locations include inter-hemispheric fissure, sylvian fissure, lateral ventricle, intracerebral, velum interpositum cistern, superior cerebellar cistern and pineal gland. They can also be extradural, usually arising in the diploic space of the calvaria, though they are less common. Magnetic resonance imaging is the primary modality for diagnosis and knowing the extent of the lesion. In this pictorial review, we intend to illustrate their classical and unusual locations, atypical imaging findings including calcifications, rare complications like haemorrhage or spontaneous rupture.