Intradiploic epidermoid cyst

Dr Henry Knipe and Dr Dalia Ibrahim et al.

Intradiploic epidermoid cysts represent epidermoid cysts that occur in the intradiploic space 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.

Plain radiograph
  • rounded or lobulated  area of bone destruction, well delineated sclerotic scalloped margins
CT
  • nonenhancing 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)
MRI
  • 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.

Share article

Article information

rID: 42420
Section: Pathology
Synonyms or Alternate Spellings:
  • Skull epidermoid cyst

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Intradiploic epid...
    Case 1: CT
    Drag here to reorder.
  • Drag
    Intradiploic epid...
    Case 1: DWI
    Drag here to reorder.
  • Drag
    Case 2
    Drag here to reorder.
  • Drag
    Case 3
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.