Walsh & Hoyt: Intracranial Epidermoids and Dermoids

Both epidermoids and dermoids apparently arise from ectopic epithelial cell rests that become sequestered at the time of the closure of the neural groove, between the 3rd and 5th weeks of gestation. It is believed that isolated ectodermal fragments migrate along with the developing-carotid, basilar, and choroidal arteries, thus explaining the various sites of intracranial epidermoids and dermoids. Although epidermoids and dermoids are often considered together under the titles of either ""pearly tumors"" or ""cholesteatomas,"" numerous investigators emphasize that there are both clinical and histologic reasons to consider them separate entities