Proliferating glia and other heterotopic tissues in the uterus: fetal homografts?

: The authors describe clinically and histologically the cases of 5 patients with glial tissue in the uterus and discuss the explanation for this rare phenomenon. The glial tissue was generally manifested as an endocervical polyp, and in one case as a large polypoid tumor on the ectocervix. Histologically, apart from glial tissue, one patient had islands of cartilage, bone, and keratinizing squamous epithelium both in the cervix and in the endomyometrial layers. Only a few investigators have found cartilage and bone in addition to glial tissue, and the authors know of no other case in which epidermal tissue has been found. The authors believe that the theory postulating the fetal origin for these foreign tissues in the uterus is the most plausible one. The specific immunologic as well as cytologic and cytogenetic factors remain to be defined.