Prenatally detected congenital orbital teratoma

Abstract

A 26-year-old Korean primigravida was referred to our hospital at 17 weeks' gestation for evaluation of a fetal brain mass. Transabdominal ultrasound imaging showed a 3.0 × 1.6-cm solid cystic mass with internal complex echogenicity in the infratentorial region of the left eyeball (Figure 1). Fetal biometry and the amniotic fluid index were consistent with gestational age and no other abnormalities were detected. The parents were informed of the poor prognosis associated with such anomalies and the pregnancy was terminated by administration of prostaglandins. A 211.5-g female fetus with a left eyeball mass was delivered (Figure 2). Coronal (a) and oblique transverse (b) views of the fetal face, showing protruding left eyeball. Protruding mass of left eye as seen at birth. No visceral malformations were observed on autopsy. Microscopic examination revealed a left orbital teratoma associated with persistent hyperplastic primary vitreous. The extraocular area showed a mature teratoma consisting of gastrointestinal mucosa, duct and glandular structures, smooth muscle and brain tissue (Figure 3). Low power (a, × 10) and high power (b, × 40) sections showing congenital orbital teratoma. Teratomas are one of the most common tumors in infants, especially in the sacrococcygeal region, gonads, retroperitonium and mediastinum. However, they account for only 6% of tumors in the head and neck region1. Congenital intracranial teratomas are especially rare and are usually extensive when first identified. Intracranial teratomas originate in the vicinity of the pineal gland, quadrigeminal plate, or the walls of the third ventricle in a medial position. Alternatively, the neoplasm, composed of multiple tissues foreign to its origin site, may arise from plastic pluripotent embryonic tissue that had escaped organizing influences in early development2. Three forms of congenital intracranial teratomas have been described: massive intracranial teratomas replacing the brain; small intracranial teratomas producing hydrocephalus; and intracranial teratomas extending into the orbit or neck3. Teratomas initially present with polyhydramnios, a fetal head size larger than expected for gestational age and massive destruction or compression of the brain4. Intracranial teratomas occur supratentorially in at least two-thirds of reported cases, with infratentorial teratomas being less common5, 6. Orbital teratomas, located in the infratentorial region and occurring unilaterally at birth, usually coexist with a normal eye and grow rapidly postnatally, causing destructive proptosis and exposure keratopathy. In some cases, however, growth may be slow, with the teratoma expanding gradually over the course of several years7, 8. Routine ultrasound examination during pregnancy allows for the early antenatal detection of teratomas. Ultrasound imaging is well suited to the diagnosis of intracranial teratomas in utero because of its ability to detect features such as calcifications, multicystic components, cranial enlargement, gross distortion of normal cerebral architecture by a hyperechoic, multicystic mass, and polyhydramnios9, 10. The prenatal diagnosis of teratomas is important for timely counseling of the parents and as an aid in obstetric decision-making. Unlike other cases generally reported, our case decribes an infratentorial mass, without polyhydramnios. Unique to our case is the fact that on ultrasound examination, the mass was found to be confined to the orbital area, prior to 20 weeks' gestation, rather than in the third trimester or after birth. To the best of our knowledge, our case is the only case of orbital teratoma prenatally detected by ultrasonography. Although exceedingly rare, congenital orbital teratoma should be added to the prenatal differential diagnosis of infratentorial masses. Y.-J. Moon*, H.-S. Hwang*, Y.-R. Kim*, Y.-W. Park*, Y.-H. Kim*, * Department of Obstetrics and Gynecology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, South Korea