CT and MR imaging features of intracerebral epidermoid – a rare lesion

Abstract

We present a rare case of intracerebral epidermoid cyst with partial calcification on CT and a characteristic hyperintense signal on diffusion-weighted MR imaging (DWI). MR imaging with DWI may help to accurately distinguish the lesion from other cystic tumours of the brain.

Clinical characteristics and diagnostic imaging of epidermoid tumors

“…17 Cyst contents are generally described as white, soft, structure-less, waxy/ cheesy debris, although epidermoid fluid has also been documented as thick, brown and viscous. 9,18 The lesion has a slow linear growth rate of one generation per month, similar to the turnover of normal human skin. 2,3,[19][20][21] However, rapid enlargement has been noted in unique cases of malignant transformation and hemorrhage.…”

“…2,3,[6][7][8] During this same period of embryogenesis, the otic and optic vesicles are also being formed, and it is believed that migration along these or other developing neurovascular structures accounts for the lateral displacement seen in most epidermoid cysts. 6,9,10 It is speculated that inclusions occurring prior to the third week of embryologic development may result in intraventricular and intracerebral lesions, as this coincides with formation of the primary cerebral vesicle. 9,11,12 Lesions localized to the extradural and diploic regions are believed to originate from aberrant ectodermal remnants that become trapped after neural tube closure.…”

“…6,9,10 It is speculated that inclusions occurring prior to the third week of embryologic development may result in intraventricular and intracerebral lesions, as this coincides with formation of the primary cerebral vesicle. 9,11,12 Lesions localized to the extradural and diploic regions are believed to originate from aberrant ectodermal remnants that become trapped after neural tube closure. 13 The cysts are lined with keratinizing stratified squamous epithelium.…”

“…1,3,4,6,14,15 Calcification is believed to be present in 10% of intracranial epidermoids. 9,16 Grossly, the lesion is well-defined with either a smooth or lobulated, cauliflower-like surface, contained within a pearly colored capsule. 3,6 However, there have been reports of a few cases where no histologically discernable capsule was identified.…”

Diagnostic Importance of Flair and Diffusion Weighted Magnetic Resonance Imaging of the Atypic Intracranial Epidermoid Cysts

“…ECs commonly occur in the cerebellopontine angles, suprasellar, and parasellar regions. In contrast, ECs in the fourth ventricle or intradiploic locations are very rare, accounting for less than 5% of all intracranial ECs (3). Because of the locations, fourth ventricle ECs may cause a mass effect on brainstem structures; intradiploic space ECs may invade the calvarium, meninges, and adjacent brain parenchyma.…”