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PINEAL TUMORS

(A Patient Information Service)

The Pineal Gland, a small structure lying in the very center of the brain, is rather peculiar since its precise function has never been fully understood. It has a role in the production of "Melatonin", a hormone, the lack of which has been associated with "jet-lag".

While rare, Pineal Gland Tumors and Pineal Region Tumors account for less than 1.5% of all human brain tumors. The symptoms caused by these tumors, result from tumor invasion or compression of the various nearby anatomical structures and are influenced by the different pathological entities that comprise the group called "Pineal Region Tumors".

Among the symptoms produced by these tumors, the most common are related to local pressure. Because of its critical, central, anatomical location, these tumors can obstruct normal Cerebrospinal Fluid (CSF) pathways by compressing the Cerebral Aqueduct (or Aqueduct of Sylvius), a small channel connecting the Third to the Fourth Ventricle. This results in a condition known as "hydrocephalus" ("water on the brain"). Since CSF is constantly being produced, any obstruction to its flow pattern or rate of reabsorbtion will result in a "ballooning" of the ventricular system and increased intracranial pressure. This is manifested by headaches, vomiting, lethargy and altered mental status. Compression of the adjacent brain structure the Superior Colliculus causes visual disturbance, the most common of which is Parinaud's Syndrome (inability to look upward, double vision and nystagmus - a flickering of the eyes back and forth). Direct invasion of the Thalamus can cause loss of sensation to half the body, weakness of half the body, and intermittent pain. Invasion of the vital centers of the Hypothalamus can cause disturbances in body temperature and water regulation, sleepiness, and weight gain. Other symptoms include memory problems, poor coordination and tremors.

The diagnosis of a Pineal Region Tumor is best established by MRI scanning since it has better resolution compared to CT scan.

There are certain helpful additional investigations that can be done once a Pineal Region Tumor is identified. Blood tests for "tumor markers" can be used to identify certain types of tumors. The most useful and specific markers for Pineal Region Tumors are beta human chorionic gonadotropin (▀-HCG) and the alpha-fetoprotein (AFP). ▀-HCG is produced by Choriocarcinoma and Geminomas and can be detected in the blood and cerebrospinal fluid. Elevated AFP suggests a malignant germ cell tumor, most often Endodermal Sinus Tumor. Elevation of both markers can be found in Embryonal Cell Carcinomas, Malignant Teratomas, or Mixed Germ Cell Tumors.

PINEAL TUMOR PATHOLOGY

Pineal Parenchymal Tumors (Pineoblastoma and Pineocytoma)

Tumors of the Pineal Parenchymal Cells are the second largest group of Pineal Region Tumors, accounting for 30% of all tumors in this location. There are two types of tumors in this group, Pineoblastoma and Pineocytoma, differing only by their histological appearance, level of differentiation and degree of malignancy.

Germ Cell Tumors (Pure Germinoma, Embryonal Cell Carcinoma, Endodermal Sinus Tumor, Choriocarcinoma, Immature Teratoma and Mature Teratoma)

Germ Cell Tumors account for more than half of all Pineal Region Tumors. Pure Germinomas account for 65% of all intracranial Germ Cell Tumors. Germinomas are poorly circumscribed and often seed the ventricular system. The Embryonal Cell Carcinoma, the least frequently reported intracranial Germ Cell Tumor, is usually highly malignant as are the rare and highly invasive Endodermal Sinus Tumors. Teratomas can be either immature or mature and represent the expression of embryonic differentiation in germ cell tumors. These well circumscribed tumors are usually round or lobulated and multicystic. They produce symptoms by compressing the surrounding structures.

Tumors of Supportive Tissues & Adjacent Structures (Astrocytomas, Ependymomas, Meningiomas, Hemangiopericytomas)

Each of these tumors produce symptoms related to their size (mass) by compressing surrounding anatomical structures (as described above) and/or by virtue of their capacity to invade the surrounding brain substance (as can occur with Astrocytomas and Ependymomas).

Metastatic Tumors
While quite rare, metastatic malignancies can affect this region producing symptoms consequent to compression, as well as invasion.

Nonneoplastic Mass Lesions (Pineal Cysts, Arachnoid Cysts, Cysticercus Cysts, Vein of Galen Malformation)

All of these pathological entities produce symptoms by compressing surrounding anatomical structures. All are amenable to surgical management.

TREATMENT

Historical Perspective

The surgical management of Pineal & Pineal Region Tumors lagged well behind surgical treatment of other brain problems, because of the central location within the cranial cavity and the vulnerability of the many vital brain centers in this location. For decades the Pineal Region was considered to be "No Man's Land". One of the surgeons who founded Neurosurgical Consultants was among the first to successfully remove various types of tumors and pathological structures in the Pineal Region. Dr. Martin Lazar first reported the resection of Third Ventricular Ependymoma, Pineal Region Meningioma as well as Tumors of the Anterior Superior Cerebellum at the 1973 Annual Meeting of the American Association of Neurological Surgeons titled: "To Galen and Back: Surgical Excision of Pineal Region Tumors". At that time, and in subsequent scientific presentation, he described a microneurosurgical occipital transtentorial direct approach, which was adapted from a concept introduced in an earlier neurosurgical era by Poppen. Subsequent publications by Dr. Lazar established this technique and the possibility for Neurosurgeons to access this region successfully. Other Neurosurgical authors have described their experiences with this and other surgical approaches to this region.

For further information, please consult Direct Surgical Management of Masses in the Region of the Vein of Galen. Surgical Neurology 2:17-21, 1974. (Lazar, M.L., and Clark, W.K.), Thrombosed Aneurysm of the Vein of Galen (Six, E.G., Cowley, A.R., Kelly, D.L., and Laster, D.W.) Critique and Comments, Neurosurgery 7:274-278, 1980. (Lazar, M.L.), Pineal Region Meningioma: Report of Two cases and Literature Review (Piatti, J.H. and Campbell, G.A.) Critique and Comments, Neurosurgery 2:369-375, 1983. (Lazar, M.L.)

Surgery

Prior to the introduction of microneurosurgical techniques and limited access procedures, the treatment of Pineal Region Tumors was largely confined to shunting of the ventricles to control the hydrocephalus followed by radiation therapy. Mortality rates were high.

Modern treatment of Pineal Region Tumors involves:

  • Control of hydrocephalus
  • Complete surgical removal of benign encapsulated tumors of the Pineal Region
  • Histological identification of nonresectable followed by radiation and chemotherapy
Stereotactic biopsy (which has low morbidity and mortality rates and gives satisfactory biopsy samples) of Pineal Region Tumors is an alternative to direct surgical exposure and may be preferable for certain types of tumors that are clearly not surgically resectable and can be treated with other techniques. Endoscopic surgery can also be accomplished and offers some advantage over stereotactic biopsies, in that the surgeon can actually inspect the lesion and surrounding tissue prior to taking samples. Stereotactic Image Guided Endoscopic Techniques are now available in some centers.

Radiation Therapy

More than 70% of Pineal Region Tumors are responsive to radiation therapy within 3 to 6 months of treatment. Germinomas are particularly responsive to radio-therapy. In many instances, ventricular shunting followed by radiation therapy, is the treatment of choice.

Chemotherapy

Chemotherapy treatment is effective for some Pineal Region Tumors with the choice of chemotherapeutic agents being dependent upon the type of tumor.



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This page last edited on 2/20

All content ©2016 by Neurosurgical Consultants, P.A.
Author, Martin L. Lazar, MD, FACS
All Rights Reserved. See Usage Notices.