intradiploic epidermoid cyst

Intradiploic epidermoid cysts represent epidermoid cysts that occur in the diploë of the skull.

Clinical presentation

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) 
  • intradiploic epidermoids are less frequent than the intradural variety

Radiographic features

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

Plain radiograph
  • 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

History and etymology

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

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

Differential diagnosis


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