Pineal yolk sac tumor

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Synonyms and keywords: Pineal yolk sac tumors; Pineal yolk sac tumour; Pineal yolk sac tumours; Pineal endodermal sinus tumor; Pineal endodermal sinus tumors; Pineal endodermal sinus tumour; Pineal endodermal sinus tumours; Pineal yolk sac carcinoma; Pineal yolk sac carcinomas; Pineal gland tumor; Germ cell tumor; Brain tumor

Overview

• Pineal yolk sac tumor is a rare type of extra gonadal yolk sac tumor. They make up a small fraction of all intracranial germ cell tumors and an even small fraction of pineal masses overall.
• Pure pineal yolk sac tumors secrete AFP.
• On microscopic histopathological analysis, pineal yolk sac tumor is characterized by poorly differentiated endothelium-like, cuboidal, or columnar cells with prominent nucleoli and significant mitotic activity.
• Pineal yolk sac tumor is demonstrated by positivity to tumor markers such as AFP, cytokeratin, and AAT. PAS-diastase positive hyaline globules and Schiller-Duval bodies are the characteristic features of pineal yolk sac tumors.
• In upto 50% of cases, these tumors co-exist with other germ cell tumors.
• Pineal yolk sac tumor may be associated with Down syndrome.
• Common complication of pineal yolk sac tumor includes obstructive hydrocephalus.
• Prognosis of pineal yolk sac tumor is generally poor.
• Symptoms of pineal yolk sac tumor include headache, nausea, vomiting, weakness, confusion, and somnolence.
• Head CT scan and brain MRI may be helpful in the diagnosis of pineal yolk sac tumor.
• On head CT scan, pineal yolk sac tumor is characterized by a hypodense, heterogenous mass in the pineal region with signs of obstructive hydrocephalus.
• On brain MRI, pineal yolk sac tumor is characterized by hypointensity on T1-weighted images and hyperintensity on T2-weighted images. There may be enhancement after contrast administration.
• Biopsy is generally done to confirm the diagnosis of pineal yolk sac tumor.

Historical Perspective

• Tumors of brainstaim as well as pineal gland,were unoperable until late of 20th century.
• Dr Cushing reported one of the first case in 1904.
• Dr Horsley in 1905was the first who did direct surgical intervention,and in 1913 Dr Oppenhein and Krause resected pineal tumor sucssesfully.

• There are only two case Reports of pineal yolk sac tumor that are associated with Down's syndrome in English literature.

Classification

• There is so many classification system for pure pineal tumors.
• The most current system is for World Health Organization(WHO).
• Louis and associates edited classification of Central Nervous System tumors and published in 2007.

Adapted from WHO:

TUMOR	FREQUENCY	ORIGIN
GERMCELL TOMURS	60%	Rest of germ cells
GerminomaMATURE TERATOMAMATURE TERATOMATERATOMA with Malignant Transformstion Yolk sac tomur (endodermal sinus tumor) Embryonal carcinoma Choriocarcinoma
PINEAL PARANCHIMAL TUMORS	30%	pineal glandular tissue
pineocytoma (WHO grade 1) pineal paranchymal tomur of intermediate diffrentiation(WHO grade 2 or 3) pineoblastoma(WHO grade 4) papillary tumor of pineal region

TOMURS OF SUPPORTIVE AND ADJUCENT STRUCTURES	10%
ASTROCYTOMAGlioma (glioblastoma or oligodendroglioma)Medulloepithelioma		Glial cells
Ependymomachoroid plexus papilloma		Ependymal lining
MENINGIOMA		Arachnoid cells
HemangiomaHemangiopericytoma or blastomaChemodectomaCraniopharyngioma		vascular cells
NON-NEOPLASTIC TUMOR LIKE CONDITIONS		< 1%
Arachnoid cysts		Arachnoid cells
Degenerative cysts(pineal cysts)		Glial cells
Cysticercosis		parasites
Arteriovenous malformations		vascularization
CavernomasAneurysms of the vein Galen
METASTASES	<.,1%	Absence of blood - brain barrier
Lung (most common),breast,stomach,kidney,melanoma

References

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Pathophysiology

• The exact pathogenesis of extragonadal germ cell tumors is not fully understood.
• It is thought that extragonadal germ cell tumors is the result of arresting erroneously of precursos germ cells in midline migration during emberiogenesis.
• The other theory is that EGGCTs are metastases of undiagnosed primary GCTs.
• The intracranial GCTs are resulting of many mutations of MAPK/PI3K/mTOR pathway.

Causes

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Epidemiology and Demographics

• The incidence of pineal tumor is approximately [1%] of all intercranial tumors.
• The incidence of pineal tumor is 0,06 -0,07 per 100,000 persons per year.
• Patients of all age groups may develop pineal yolk sac tumor.But is more common in children(3-8%)and also in Japenes population.
• There is no racial predilection to pineal tumors.
• pineal tumors affect men more than women.
• The majority of pineal tumor cases are reported in Japenes population.

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Diagnosis

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Laboratory Findings

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CT scan

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MRI

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Treatment

• The mainstay of therapy for pineal yolk sac tumor is radiotherapy and/or chemotherapy. Sometimes, surgical resection may be done.

Management Options of Penial Gland tumors
CSF diversion	The optimal surgical strategy to treat acute hydrocephalus in patients with pineal tumors is uncertain. CSF diversion (ventriculoperitoneal [VP] shunt or third ventriculostomy may be necessary in symptomatic patients, although debulking surgery may obviate the need for this procedure When CSF diversion is necessary, endoscopic third ventriculostomy can be carried out at the same time as the biopsy and is preferred over VP shunts, which can be complicated by infection, shunt malfunction, subdural hematoma, and rarely, tumor seeding
Surgical resection	Some series report long-term survival with surgery alone, even in patients with pineoblastomas. Indeed, for pineoblastomas, gross total surgical resection appears to correlate with improved survival. Patients with symptomatic recurrent pineocytomas should also be considered for surgical resection of the lesion
Radiation	Postoperative adjuvant RT is frequently (but not universally) recommended, and local control is dose-dependent. The incidence of leptomeningeal recurrence was significantly lower among patients receiving CSI compared with those who did not. The five-year survival rates were 86 and 49 percent for pineocytomas and non-pineocytoma PPTs, respectively. Adjuvant RT is not universally recommended after gross total resection of a pineocytoma
Stereotactic radiosurgery	Stereotactic radiosurgery (SRS) is emerging as a useful treatment alternative for pineocytomas, although experience is limited. The precise radiation fields that are defined by MRI or CT-computerized treatment planning minimize damage to the surrounding brain, and the risks of general anesthesia and craniotomy are avoided. SRS is increasingly being used to treat pineal region tumors, either as an additional therapy after conventional treatments or as a primary treatment. Due to the low rate of side effects, IRS may develop into an attractive alternative to microsurgery in de novo diagnosed pineocytomas. In malignant PPTs, IRS may be routinely applied in a multimodality treatment schedule supplementary to conventional irradiation.
Chemotherapy as part of multimodality therapy	The similarity of pineoblastomas to medulloblastomas in terms of their clinical behavior and tendency for leptomeningeal seeding has led to the use of similar chemotherapy regimens in patients with pineoblastoma as part of a multimodality approach. Chemotherapy has been used to delay radiation therapy in very young children, for whom the long-term neurocognitive and developmental side effects of craniospinal irradiation (CSI) are a major concern. The importance of radiation therapy as a component of the initial treatment of supratentorial primitive neuroectodermal tumors (PNETs) is also supported by the German HIT-SKK87 and HIT-SKK92 protocols, as well as the Canadian pediatric brain tumor protocol

References

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