Epidermoids are relatively rare neoplasms which occur most frequently in and about the nervous system, particularly in its cranial portion. They have been called cholesteatomas, tumeurs perlées, Perlgeschwulst and atheroma. They may arise beneath the scalp, within the diploe, between the bone and the dura mater, beneath the arachnoid membrane, particularly about the base of the brain, or within the ventricles. It is now commonly accepted that these tumors arise from ectodermal rests—a hypothesis originally advanced by Remak1 in 1854, although it was not universally accepted until many years later. Such embryonic rests are probably remnants of an incomplete separation of the neural from the surface ectoderm. Such epithelial anlagen when located within or near the nervous structures form the intraventricular and subarachnoid epidermoids. At other times they have been deposited between the two ectodermal structures, skin and brain, and surrounded by mesodermal tissues, thus forming the epidural, intradiploic
BUCY PC. INTRADIPLOIC EPIDERMOID (CHOLESTEATOMA) OF THE SKULL. Arch Surg. 1935;31(2):190–199. doi:10.1001/archsurg.1935.01180140018002
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