What is Pineal Gland Cancer?
The pineal gland is a tiny hormone-producing gland in the middle of the brain. It is about 10 to 14 millimeters big and sits at the top border of an area called the third ventricle. From a side view, you’ll find it below a part called the splenium of the corpus callosum and above and slightly behind another part called the midbrain’s tectum. The main job of this gland is to make a hormone called melatonin. This hormone helps the brain understand changes in the environment, like the shift from day to night.
The main cells in the pineal gland are pinealocytes. Because of the pineal gland’s location, a lot of different health problems can affect it. These include tumors that can form from the cells within the gland or from other nearby cells. Other issues close to the gland can involve various parts of the brain such as the corpus callosum, the arachnoid membrane, ependymoma (a type of brain tumor), blood vessel abnormalities, and more. This article focuses on the tumors that originate from within the gland itself.
There are several important parts of the brain close to the pineal gland. These include an area in the front called the third ventricle, another toward the front and top called the habenular nuclei. At the back, we find the vein of Galen and an area between the layers of the brain called the “velum interpositum.” Also nearby are the superior cerebellar cistern at the back, the superior colliculi of the midbrain beneath, and the posterior commissure at the front and bottom.
What Causes Pineal Gland Cancer?
Pineal gland tumors are categorized based on their cellular structure. Here’s a basic understanding of the different types of these tumors:
1. Pineal Parenchymal Tumors: These tumors grow from the cells within the pineal gland itself. Different types of this category include:
* Pineocytoma: A slow-growing and typically benign (non-cancerous) tumor.
* Pineal Parenchymal Tumor with Intermediate Differentiation: A tumor with characteristics between a Pineocytoma and a Pineoblastoma.
* Pineoblastoma: An aggressive, malignant (cancerous) tumor.
* Papillary Tumor of the Pineal Region: A rare and potentially cancerous tumor.
2. Germ Cell Tumors: These are tumors that originate from cells which produce eggs or sperm. They’re categorized into either germinomatous or nongerminomatous types:
* Germinomatous Germ Cell Tumors:
* Pineal Germinoma: These are generally cancerous tumors.
* Nongerminomatous Germ Cell Tumors:
* Choriocarcinoma and Embryonal Carcinoma: Both are malignant and form from germ cells.
* Yolk Sac Tumor (also known as Endodermal sinus tract tumor): A rare malignant tumor.
* Immature Teratoma: A usually cancerous tumor made up of several different types of tissue.
* Mature Teratoma: A usually noncancerous tumor made up of tissues resembling normal tissues.
Risk Factors and Frequency for Pineal Gland Cancer
Tumors in the pineal area of the brain are rare, making up just 1% of adult brain tumors. However, in children, they represent up to 8%. There are various types of tumors in this region, each with its unique characteristics.
- Pineocytoma: Most commonly seen in adults between 20 to 60 years old and tend to be more common in females. These tumors make up 14-30% of pineal and are well-differentiated.
- Pineal Parenchymal Tumor with Intermediate Differentiation: This kind of tumors is commonly seen in middle-aged adults between 20 to 70 years and has a slight female preference. They account for 20-62% of all pineal tumors.
- Papillary Tumor of the Pineal Region: These tumors can occur at any age, from 1 to 70, and have no gender preference.
- Pineoblastoma: These are aggressive tumors making up 24 to 50% of all pineal tumors. They’re most common in young children and slightly more frequent in females.
- Germinoma: They make up for 50% of pineal tumors and are usually seen in males who are 20 years or younger. These tumors can be identified with specific markers in the cerebrospinal fluid.
- Choriocarcinoma: These are uncommon tumors that make up 5% of all pineal region masses and 10% of brain germ cell tumors. They can be identified with specific markers in the cerebrospinal fluid and blood.
- Embryonal Carcinoma: Another uncommon tumor type representing less than 5% of all pineal region masses and 10% of brain germ cell tumors. These tumors have a high likelihood of spreading.
- Yolk Sac Carcinoma (Endodermal Sinus): These are a rare type of brain tumors. They’re sometimes linked with Down syndrome, but this isn’t often the case.
- Immature/Mature Teratoma: While these tumors are infrequent, they are the most common in unborn babies, making up 26 to 50% of fetal brain tumors. The treatment and outlook can differ significantly depending on whether the tumor is mature or immature.
Signs and Symptoms of Pineal Gland Cancer
Pineal region tumors might lead to a series of symptoms because of two separate issues – obstructive hydrocephalus and the compression of a part of the brain called the tectum. It’s important to note these signs and symptoms tend to be the same no matter what type of tumor is present.
Let’s look at each one a little closer:
- Hydrocephalus: This typically manifests in ways like headaches, nausea, slow development in kids, having a larger head than usual, blurry vision, feeling sleepy or drowsy, or even falling into a coma. If a physical examination is conducted, the physician might identify what’s called Cushing’s triad: hypertension, slow heart rate, and irregular breathing. They might see some swelling in both eyes or even paralysis of the sixth cranial nerve in both eyes.
- Compression of the tectum, also known as Parinaud syndrome: Historically, patients have reported having difficulty walking up stairs or seeing double. If a doctor completes a physical exam, they might notice that the patient is unable to look upward or move their eyes downward in harmony. They might also see things like light-near dissociation (from pressure on a certain brain structure), convergence-retraction nystagmus and eyelid retraction (also known as Collier sign) which arises from damage to certain brain fibers.
Testing for Pineal Gland Cancer
If your doctor suspects that you might have certain types of tumors, they may request a blood test to check for specific substances produced by tumors, also known as tumor markers. These may include substances such as AFP, b-HCG, and placental alkaline phosphatase.
In addition, a doctor may also want to analyze your cerebrospinal fluid (CSF), which is the fluid around your brain and spinal cord. This can be collected either through a lumbar puncture, a procedure where a needle is inserted into the lower spine, or during undergoing treatment with a tube called an endoscope. This test is typically useful for most types of tumors.
When it comes to imaging, doctors usually rely on brain Magnetic Resonance Imaging (MRI), which uses powerful magnets and radio waves to create detailed images of your brain. Particularly, an MRI with and without gadolinium enhancement is considered the best method for examining tumors in the pineal region of the brain. The pineal region is in the middle of your brain and can be the site of various types of tumors.
Gadolinium is a type of contrast material. In MRI, it helps to clearly show the difference between healthy and diseased tissue. However, if MRI is not available, a head CT scan, angiography, or ultrasound (for infants) can also be of help.
Normal findings of the pineal gland on imaging would include:
– On CT scan: You would typically see small hardened areas, known as calcifications, in the pineal gland for adults. For children under the age of 5 years, these calcifications typically do not appear. Once a person reaches about 30 years of age, these calcifications usually reach a stable level.
– On MRI: The pineal gland would appear similar in color to your brain’s grey matter and would look like a small nodule in the back of the ventricle, which are part of your brain’s drainage system. It will show up brighter with the application of gadolinium because it lies outside of the brain’s protective blood-brain barrier, which helps block potentially harmful substances from reaching the brain.
The MRI will usually show consistent contrast enhancement, except for those with a diverse cell makeup. Dense tumors, like pineoblastoma and germinomas, will have restricted diffusion, which means they appear darker than normal tissues on diffusion-weighted images. On the other hand, pineal cysts, which are noncancerous growths, don’t show up brightly and usually have a thin wall; in fact, if the wall is thick, it can often rule out the presence of a cyst.
Calcifications are usually present in brain tumors and they can be more easily seen in a head CT scan. They can sometimes guide doctors towards the correct diagnosis. Tumors forming in the tissue of the pineal gland (for example, pineocytoma or pineoblastoma) usually spread calcifications around the edges, while germ cell tumors usually envelop the calcifications. A helpful way to remember this is that pineoblastomas tend to scatter the calcifications.
Pineal region tumors can sometimes cause the spread of cancer cells, either locally or at a distance. Therefore, a full spine MRI might be part of the initial evaluation. Both local spread and distant spread of the tumor can have significant implications for the prognosis – the predicted course and outcome of the disease. It can also drastically change the initial management approach and additional therapies.
Findings that indicate a worse prognosis include local invasion of the tumor into surrounding structures, the spread of tumor cells into the cerebrospinal fluid (CSF), and extensive peritumoral edema, which is swelling caused by excess fluid around the tumor.
– Local invasion is seen in tumors such as pineoblastomas, and most germ cell tumors.
– CSF spread is seen in pineoblastomas and germinomas. However, for pineoblastomas, the spread is usually distant, whereas for germinomas, it’s usually nearby.
Treatment Options for Pineal Gland Cancer
Your doctor has a step-by-step plan, called a treatment algorithm, to correctly identify and treat your health issue. This plan varies depending on whether you have hydrocephalus – that is, an accumulation of fluid in the brain – or not.
If you don’t have hydrocephalus, doctors will first test the liquid in your body (serum) and the fluid in your brain (CSF) for tumor markers, which indicate the presence of a tumor. If the tests are positive, your treatment will be based on the most likely type of tumor found. If the tests are negative, doctors need to take a small specimen of tissue (biopsy) to identify what the problem is. The way they obtain this biopsy depends on your specific case. It can be through a specialized form of brain surgery (stereotactic), through a small tube with a camera (endoscopic), or through open surgery. Finally, your treatment will be based on the findings of the pathology lab, which analyzes the nature of your disease.
If you have hydrocephalus, doctors will first devise a way to divert the build-up fluid in your brain. The preferred method is an endoscopic third ventriculostomy (ETV). This is a procedure where a small hole is made in the floor of a space in your brain (third ventricle) to let the fluid escape and relieve pressure. Doctors also use this procedure to take a biopsy of the tissue at the back of this space. If the ETV fails, a device called a ventricular shunt will be placed to drain the fluid. The final treatment plan will, again, be based on the pathology lab findings.
The ETV procedure is usually done by creating a small hole in the right front part of your skull. A camera (neuro endoscope) is inserted and navigated through your brain until it reaches the third ventricle. There, a section of the ventricle’s floor is opened and expanded to allow the fluid to escape. A biopsy is also taken during the procedure to help diagnose the cause.
The ETV success score is a system to assess how likely this procedure is to work with your specific case, using factors such as age, cause of the hydrocephalus, and previous ventricular shunt placements. Each factor contributes a certain percentage to your total success score, which ranges from 0% to 90%.
The final course of treatment depends on the specifics of your condition. Some options include surgical tumor removal, radiotherapy (irradiating the tumor), and chemotherapy (treatment with cancer-killing drugs), either alone or in combination. The chosen surgical approach to the pineal region of the brain (toward the back of the head) depends on the exact location and the surgeon’s preference.
It’s important to thoroughly screen the entire nervous system if you have a pineal region tumor since these kinds of tumors differ widely in their prognosis and treatment based on their spread to other parts of the body. However, the addition of spine radiotherapy as a preventative measure is subject to debate.
What else can Pineal Gland Cancer be?
There are several types of conditions that can occur in the pineal region of the brain, including:
- Cystic non-neoplastic lesions such as:
- Pineal cysts
- Cavum veli interpositum
- Arachnoid cyst
- Pineal parenchymal tumors like:
- Pineocytoma
- Pineal parenchymal tumor with intermediate differentiation
- Pineoblastoma
- Papillary tumor of the pineal region
- Germ cell tumors, including:
- Pineal germinoma
- Embryonal carcinoma
- Choriocarcinoma
- Teratoma (mature/immature)
- Yolk sac tumor
- Tumors also found in the pineal region such as:
- Astrocytoma
- Meningioma
- Cerebral metastases
- Pineal gland metastases
- Vascular lesions such as:
- Vein of Galen aneurysm/malformation
- Internal cerebral vein thrombosis
These conditions vary in severity and require different approaches for treatment. A correct diagnosis is crucial for effective treatment.
What to expect with Pineal Gland Cancer
Pineocytoma:
This is a type of tumor that has a relatively good chance of recovery. If removed surgically, the outlook is generally excellent, especially when the entire tumor can be taken out. This is often possible because they are well-defined masses. The survival rate five years after diagnosis is between 86% to 91%. It’s rare for this tumor to recur or spread to the spinal fluid.
Pineal parenchymal tumor with intermediate differentiation:
This tumor’s prognosis falls between pineocytoma and pineoblastoma. They are more likely to be confined to one specific area. The median overall survival is around 165 months (about 14 years), while patients usually remain disease-free for about 93 months (about 8 years). This is better than pineoblastoma, with its median survival and disease-free periods being around 77 and 46 months respectively.
Pineoblastoma:
This is the most aggressive of these types of tumors. The median survival time tends to be between 4 to 8 years. The survival rate five years after diagnosis ranges from 10% to 81%. Factors that can negatively impact the prognosis include if the disease has spread at the time of diagnosis, if the patient is young, and if it’s not possible to remove all of the tumor surgically. Chemotherapy and potentially stem cells treatment can improve the outcome.
Papillary tumor of the pineal region:
Local recurrence of the disease often impacts the prognosis. The five-year survival rates were 73%, while the tumor remained stable in only 27% of patients. Complete surgical removal and diagnosis at a younger age are linked to better survival odds, while radiotherapy and chemotherapy showed no significant benefits. Screening of the entire nervous system is necessary because the disease can spread to the spinal fluid in up to 7% of conditions.
Germinoma:
This tumor is highly responsive to radiation, with long-term survival rates of over 90% after craniospinal radiation. The addition of chemotherapy to the treatment plan may offer comparable control over the tumor at lower radiation levels. Spread of this disease within the brain’s lining or fluid-filled structures isn’t uncommon at diagnosis, occurring in 13% of cases.
Mature teratoma:
This type of tumor can often be cured by complete surgical removal.
Immature teratoma:
This tumor, like germinoma, has an intermediate position in terms of biological behavior. The size and location of the tumor play a crucial role in determining the prognosis.
Embryonal carcinoma, choriocarcinoma, and yolk sac tumor (endodermal sinus):
These are the most aggressive types of germ cell tumors. However, survival rates as high as 60-70% can be achieved with combined chemotherapy and radiation. Recurrence of the disease and spread to the spinal fluid are common ways the disease progresses.
Possible Complications When Diagnosed with Pineal Gland Cancer
The tumor can result in different issues, such as:
- Problems with the hypothalamus and hormone production
- Trouble with eye movements
- Bleeding
- A type of stroke caused by a clot in a vein
- Seizures or convulsions
- Weakness on one side of the body
- Coordination problems, leading to a lack of balance or clumsiness
Preventing Pineal Gland Cancer
It’s possible for any of these tumors to reappear even after a lengthy period, which is why it’s crucial to have ongoing health check-ups. Patients with cerebral shunts, which are devices that help to manage the flow of fluid in the brain, also need to have their health assessed regularly for the rest of their lives. The outlook and type of treatment depend heavily on the nature and type of the tumor. It’s vital for patients and their families to understand their specific type of tumor and learn about any additional treatments that may be necessary.
