Epidermoid cyst of the ovary. A report of three cases with comments on histogenesis.

Three cases of epidermoid cyst of the ovary are presented. In each case small epithelial nests were found in the wall of the cyst, which, on serial section, proved to be focally cystic with mucin and keratin debris in their lumens. A comparative study of these epithelial nests, Walthard nests, and the epithelial components of a Brenner tumor revealed striking morphologic similarities. The findings suggest that epidermoid cysts originate from epithelial cell nests of the type encountered in Brenner tumors.