"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 occur within the frontal, parietal, occipital and sphenoid bones, as well as the spine 1."
"History and etymology"