Intradiploic epidermoid cyst

Last revised by Mostafa Elfeky on 6 Dec 2023

Intradiploic epidermoid cysts refer to epidermoid cysts that occur in the diploë of the skull.

Painless slowly progressive scalp swelling.

  • epidermoid cysts may be congenital (most common, arising from ectodermal inclusion during neural tube closure and subsequently remain within the cranial bones) or acquired (e.g. post-surgical or post-traumatic implantation) 4

  • intradiploic epidermoids are less frequent than the intradural variety 1

Intradiploic epidermoids occur within the frontal, parietal, occipital and sphenoid bones, as well as the spine 1.

  • rounded or lobulated area of bone destruction, well-delineated sclerotic scalloped margins

  • non-enhancing hypodense lesion with sharply demarcated bony defects and zones of calcifications

  • it may alter the outer and/or inner tables of the skull (the inner table more than the outer)

  • T1: slightly hyperintense to the CSF

  • T2: isointense/hyperintense to the CSF

  • FLAIR: hyperintense to the CSF space

  • DWI: restricted diffusion with characteristic hyperintensity

  • T1C+: none

The first intradiploic epidermoid cyst was reported by J Müller in 1838 5.

The radiological pattern of intradiploic epidermoids was first described by Cushing in 1922.


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