Intradiploic epidermoid cyst

Intradiploic epidermoid cysts represent epidermoid cysts that occur in the diploe 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 occurs within the frontal, parietal, occipital, 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 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 radiological pattern of intradiploic epidermoids was first described by Cushing in 1922.


Bone tumours

The differential diagnosis for bone tumours is dependent on the age of the patient, with a very different set of differentials for the paediatric patient.

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Article information

rID: 42420
Synonyms or Alternate Spellings:
  • Skull epidermoid cyst
  • Diploic epidermoid cyst

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Cases and figures

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    Case 1: CT
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    Case 1: DWI
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    Case 2
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    Case 3
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    Case 4: with external angular orbital extension
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    Case 5: orbital intradiploic epidermoid cyst causing proptosis
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