The epidermoid, dermoid and teratoma are essentially similar tumors both in their development and in their clinical course. They belong to the tumors of mixed tissue which arise from cell rests. The type of tumor depends on the embryonic derivation of its elements. When the neoplasm contains tissues from all three germ layers it is considered a true teratoma. When tissues of mesodermal as well as epithelial origin are represented, it is called a dermoid cyst. The most common and simplest type, the epidermoid, is composed of elements of but one germ layer, the ectoderm. Sections from different areas in the wall of a single tumor have occasionally shown dermoid in one part and epidermoid in another.1 These mixed tumors, comprising a rare but interesting group of neoplasms of the central nervous system, are discussed under the following subdivisions, and 14 cases observed are reported.
INTRACRANIAL EPIDERMOID, OR CHOLESTEATOMA
PEYTON WT, BAKER AB. EPIDERMOID, DERMOID AND TERATOMATOUS TUMORS OF THE CENTRAL NERVOUS SYSTEM. Arch NeurPsych. 1942;47(6):890-917. doi:10.1001/archneurpsyc.1942.02290060028002