Epidermoid cysts of the ovary: a report of five cases with histogenetic considerations and ultrastructural findings.

Five cases of epidermoid cysts of the ovary are added to the two-reported in the literature. This rare lesion was uniformly an incidental finding in the study of hysterectomy specimens. Its main interest is in its histogenesis, which is suggested to involve metaplasia of the coelomic surface epithelium of the ovary. Ultrastructural evidence is one case strongly favors this possibility, thus adding another line of differentiation to those already established for the multipotent coelomic epithelium. However, some cases may be teratoid in origin, as has been suggested for the analogous lesion in the testis.