Intracranial Germ Cell and Pineal Tumors
Background
What are the 2 broad categories of germ cell tumors?
Gonadal and extragonadal
What are the 3 subtypes of extragonadal germ cell tumors?
Sacrococcygeal, retroperitoneal, and intracranial
What are the 2 subtypes of intracranial germ cell tumors?
Germinoma and nongerminomatous germ cell tumor (NGGCT)
What are 4 subtypes of intracranial NGGCTs?
Endodermal sinus tumor (yolk sac), choriocarcinoma, teratoma, and embryonal
Germ cell tumors represent what % of pediatric and adult brain tumors?
Pediatric: 3%–11%
Adult: 1%
Are germinomas or NGGCTs more common?
Germinomas are more common (two thirds of all intracranial germ cell tumors)
What are the median age at Dx and the gender/race predilection for germinomas?
10–14 yrs, males > females (2:1), Asian > white (4% vs. 1% pediatric CNS tumors in Asia vs. the U.S.)
Where do the majority of intracranial germinomas and NGGCTs arise?
Midline proximal 3rd ventricular structures: two thirds pineal and one third suprasellar
What % of germinomas have CSF dissemination at Dx?
15%–20% (50% of pineoblastomas have leptomeningeal dissemination.)
What is the probability of spinal failure in pts with various types of pineal-based tumors without evidence of spinal seeding at Dx?
Mature and immature teratoma: 0% (0/16)
Mixed NGGCT: 4% (1/24)
Other NGGCT: 39% (3/9)
Germinoma: 17% (8/46)
Pineocytoma: 0% (0/7)
Pineal parenchymal tumor (PPT), pineoblastoma, or PPT of intermediate differentiation: 17% (20/116)
(Schild SE et al., Cancer 1996)
What is the typical presentation of a tumor in the pineal region?
↑ICP, Parinaud syndrome (decreased upward gaze, accommodates but abnl light response)
How do pts with suprasellar masses present?
Triad of visual difficulties, diabetes insipidus (DI), and precocious or delayed/abnl sexual development
Pressure/mass effect on what anatomic structure causes Parinaud syndrome?
Pressure/mass effect on the superior colliculus causes Parinaud syndrome.
Workup/Staging
What is the DDx for a pediatric brain tumor in the pineal region?
Pineoblastoma, pineocytoma, PPT of intermediate differentiation, germinoma, NGGCT; 80% of pineal-region tumors are germ cell tumors.
What is the workup for a suspected germ cell tumor?
Suspected germ cell tumor workup: H&P (especially CNs, fundoscopy), MRI brain/spine, basic labs, serum AFP/β-HCG, CSF AFP/β-HCG, and CSF cytology
What AFP levels exclude the Dx of a germinoma?
If an AFP is >10 ng/mL,
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