Orbital germ cell tumors revisited: a clinicopathological approach to classification.

Orbital teratomas are unilateral, congenital germ cell tumors, which present at birth with moderate to massive proptosis, leading to exposure keratopathy. They enlarge the orbit diffusely. Primary orbital teratomas cause axial or vertical proptosis, are usually unassociated with bony defects, and do not extend outside the orbit. Recurrence is unusual after an early excision without enucleation or exenteration. Combined orbital teratomas additionally involve periorbital and intracranial spaces, cause lesser degrees of proptosis, and typically are associated with defects of orbital bones. Their intracranial part is small as compared to the orbital one. A significant risk of recurrence exists even after a combined craniotomy, orbitotomy and plastic reconstructive surgery. Intracranial teratomas with secondary orbital spread present prenatally with polyhydramnois and hydrocephalus, due to a massive primary tumor replacing parts of the brain, and typically lead to stillbirth. One orbital teratoma with malignant change has been well documented. Included twins, monsters rather than neoplasms, represent parts of a second fetus in the orbit. Orbital yolk sac carcinomas or endodermal sinus tumors are malignant neoplasms affecting children, which frequently invade periorbital and intracranial spaces, and which may respond to chemotherapy and irradiation. Finally, a teratoma or a yolk sac carcinoma may rarely present as an intraocular tumor.