Pineal tumors are a form of tumor that develops in the pineal gland or around the pineal region of the brain. They're classified as central nervous system (CNS) tumors. In advanced cases, they can also spread to the spinal cord.
All CNS tumors are categorized by the World Health Organization (WHO) under a four-point grading system. Grade 1 tumors are usually benign, slow-moving, or easily removable. In contrast, grade 4 represents the fastest-growing and most aggressive types.
Tumors of the pineal region are relatively rare and account for about 1% of adult brain tumors — usually occurring between the ages of 20 and 40. But they are more common in children, accounting for around 3% to 11% of pediatric brain tumors.
Symptoms, prognosis, and treatments for pineal tumors depend on the tumor’s type, region, and grade.
What Is the Pineal Gland?
The pineal gland is small and pine cone-shaped, located deep in the brain’s center. We still don’t fully understand the function of the pineal gland, but we know it helps regulate sleep.
Melatonin and its precursor, serotonin, are both synthesized in the pineal gland and derived chemically from tryptamine. Melatonin is a natural hormone that regulates sleep, mood, digestion, nausea, wound healing, blood clotting, and sexual desire.
The pineal gland also helps regulate the balance of female hormones, influencing fertility and menstrual cycles.
What Causes Pineal Tumors?
We still don’t know what causes pineal tumors. But those with an inherited genetic disorder called bilateral retinoblastoma — a rare form of cancer affecting the eyes — may be at higher risk of developing pineal region tumors.
What Are the Symptoms of Pineal Tumors?
Pineal tumor symptoms are often associated with the feeling of pressure inside the skull.
One of the most common symptoms is a condition called hydrocephalus. Hydrocephalus is a buildup of cerebrospinal fluid (CSF) in the brain, which leads to increased compression and can result in several symptoms:
- Early signs of puberty
- Double vision, or diplopia
- Memory issues
- Poor balance and coordination, known as ataxia
- Trouble sleeping
- Unusual eye movements
Pineal tumors can also impact the endocrine system, which helps the body regulate hormone levels and production.
How Can Doctors Diagnose Pineal Region Tumors?
Your doctor will first ask about your family history and any symptoms you’re experiencing. You may also get a neurological exam to test for reflexes, eye movement, motor function, sensations, coordination, and balance.
If your doctor thinks you might have a pineal tumor, they may order more tests, which can include:
Magnetic resonance imaging (MRI) scan. MRIs are one of the most common and preferred ways to scan for pineal region tumors. They use magnets and radio waves to create detailed images of the spinal cord and brain.
Computed tomography (CT) scan. CT scans are another form of imaging. They use X-rays and a computer to create pictures of the brain so doctors can see the tumor and its surrounding structures.
Biopsy. Your doctor can remove a small number of tumor cells for examination. Biopsies can determine the type and grade of pineal tumors.
Blood tests. Your doctor could also take blood samples to test for biochemical markers of pineal tumors. They may also take a sample of your cerebrospinal fluid for testing.
What Are the Different Types of Pineal Tumors?
Pineal tumors have several different classifications depending on their severity and point of origin.
Various tumors can start in the pineal region of the brain but don’t necessarily involve the pineal gland. Due to the diversity of cells in this region, a variety of tumor types can develop:
Germ cell tumors. Germ cell tumors, or germinomas, account for over half of pineal region tumors. Some of these include embryonal cell tumors and choriocarcinomas, which tend to be malignant and more aggressive.
Gliomas. Gliomas like astrocytomas are tumors that arise from glial cells. They make up about a third of all pineal region tumors.
Others. Other types of tumors, like meningiomas, gangliogliomas, and hemangioblastomas, can also develop, although they make up a small portion of these tumors.
Papillary tumor of the pineal region (PTPR). Papillary tumors develop from cells that line the brain’s cavities and the central canal of the spinal cord. They are classified as WHO grade 2 or 3 and tend to occur more in adults than children.
Tumors originating inside the pineal gland itself fall under three categories:
Pineocytoma. These tumors arise from pinealocytes, the main cells in the pineal gland. They are slow-growing and classified as WHO grade 1. Pineocytomas are often benign or relatively easy to remove with surgery. They can develop at any age but are most common in adults between 20 and 60.
Pineal parenchymal tumors. Also known as mixed pineal tumors, these arise from a mixture of different cells inside the pineal gland. They can be classified as WHO grade 2 or 3 and usually return after initial treatment.
Pineoblastoma. Classified as WHO grade 4, pineoblastoma is a fast-growing, malignant tumor likely to invade and spread to nearby tissue in the brain and spine. Pineoblastomas are aggressive and the most difficult to treat. They occur slightly more frequently in women and are most often diagnosed in people under 20.
What Are the Treatment Options for Pineal Tumors?
Surgery. Surgery is often the first line of treatment for pineal tumors. Doctors will perform a craniectomy, a procedure where they remove a small part of the skull to access the tumor. Surgery can often successfully eradicate a benign tumor. But for malignant and more advanced pineal tumors, it’s too risky to try and remove the whole thing without damaging the surrounding tissue. Still, even partial removal of a tumor during surgery will improve the effectiveness of other treatments.
Radiation therapy. Radiation therapy (or radiotherapy) can happen after surgery or be the primary treatment for pineal tumors. This type of therapy is particularly effective with germ cell tumors.
Chemotherapy. Doctors may also recommend chemotherapy, which attacks the tumor with powerful chemical drugs. They could order chemotherapy after or instead of radiotherapy. It's the preferred treatment for children under 3 years old.
What’s the Prognosis for Pineal Tumors?
The prognosis for pineal region tumors will depend on the tumor’s type and severity. A grade 1 tumor can be cured, but grade 4 tumors are much more of a challenge to treat.
The relative five-year survival rate for tumors of the pineal region is 69.5%.
Grade 1 pineocytomas have a five-year survival rate as high as 86%, but the rate drops to 8.3% in children under 4 years old with grade 4 pineoblastoma. But this number rises to 66.7% in people aged 4 years or older.
Remember to always talk to your doctor about prognosis and treatment options.