Teaching Case

An 18-year-old male presented to our hospital with headache, nausea and vomiting.

An 18-year-old male adolescent presented to our hospital with headache, nausea and vomiting. The physical examination revealed signs of increased intracranial pressure. The patient was immediately referred to the department of Radiology for CT scan. Prominent obstructive hydrocephalus was found due to a pineal region hypodense mass. Following MRI demonstrated a heterogeneous tumor with hyperintense areas in the pineal region. Fatty components were spread in the subarachnoid space, third ventricle and the aqueduct of Sylvius arousing suspicion of tumor rupture. Levels of AFP and bhCG were normal. The patient was treated for hydrocephalus with ventriculoperitoneal (VP) shunt prior to resection.During the operation, the mass was totally removed. Histological findings proved this tumor to be a mature teratoma, showing three germ cell layers.

Teratoma is a rare intracranial tumor that occurs most commonly in the pineal region, less commonly in the suprasellar region and rarely inside the third ventricle. Pineal teratomas are found almost exclusively in males, especially in the second decade of life. Most patients present with hydrocephalus and/or Parinaud's syndrome (syndrome of vertical gaze palsy that can be associated with pupillary or oculomotor nerve paresis). Rarely, these tumors rupture, spilling their fatty contents into the subarachnoid space and giving rise to severe chemical meningitis. Pathologically, teratomas may contain fat, cartilage, bone, hair, and cysts. Hosoi first used the term teratoid in 1930 to describe less structured tumors in which derivatives of all 3 germinal layers could not be identified easily. Current classification of these tumors divides them into mature and immature teratomas. Mature teratomas contain fully differentiated ectodermal, mesodermal, and endodermal elements, whereas immature teratomas have more primitive elements that closely resemble embryonic histology. Malignant teratomas (teratocarcinomas) secrete alpha-fetoprotein(AFP). The radiographic hallmark of these tumors is the presence of lipid combined with calcifications. When a midline, heterogeneous mass is seen by either CT or MRI, teratoma should be strongly considered. Teratomas are well-circumscribed and they are characterized by their heterogeneity, multilocularly, and irregular enhancement. These tumors also can demonstrate ring enhancement. Occasionally, teratomas can be totally homogeneous. In some cases, a well-circumscribed teratoma has areas of low attenuation that correlate with adipose tissue, which serves to further distinguish it from other pineal region tumors. The differential diagnosis of masses arising in the pineal gland region also includes tumors of germ cell origin (germinoma, embryonal cell carcinoma, endodermal sinus tumor, and choriocarcinoma) and tumors from pineal cell origin (pineocytoma and pineoblastoma). Germinomas (also called dysgerminomas) are the most common pineal mass (over 50%) and are found predominantly in males. They show significant contrast enhancement by both CT and MR, do not contain calcifications, and commonly have subarachnoid seeding. Embryonal cell carcinomas are seen in both sexes, demonstrate contrast enhancement on both CT and MR, but do not contain calcifications. They may secrete human chorionic gonadotropin (HCG) and can seed in the subarachnoid space. Choriocarcinoma can bleed spontaneously, show contrast enhancement, and is devoid of calcifications. With the exception of teratoma, almost all pineal germ cell tumors are radiosensitive (germinoma being the most radiosensitive).