Placental teratoma with three-germ layer differentiation.

A rare case of placental teratoma is described. Major features were the presentation as a pedunculated mass from the fetal surface of the placenta, the mixture of different tissues derived from all three germ layers (skin with dermal appendages, ganglion-like cells, and nervous structures, gut structures, osteocartilagineous and smooth and striated muscle), and the absence of segmental organization.