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.

Consider:

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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