Pineal Tumor – Types, Risk Factors, Diagnosis and Treatment

Definition

Pineal tumor is an abnormal growth in or near the pineal gland. Depending on the type of tumor, surgery may involve a craniotomy to remove it. The pineal gland, a tiny, pinecone-shaped area located in the midline of the brain behind the third ventricle, synthesizes and secretes the neurotransmitters melatonin, which plays the critical role of regulating the body’s circadian rhythm, and serotonin, a precursor to melatonin. Other functions of the pineal gland remain incompletely understood. This gland is composed of a variety of cells, such as glial cells, endothelial cells, sympathetic nerve cells, pineal parenchymal cells and germ cells. Given the diversity of cells, a wide variety of tumor types can arise in this region.

Epidemiology

In Europe and North America, pineal tumors account for less than 1 percent of all primary brain tumors. Pineal tumors are more common in children aged 1 to 12 years where these constitute approximately 3 percent of brain tumors.

Worldwide, pineal tumors are most common in Asian countries, for reasons that are not known. This increased frequency is due largely to an increase in germ cell tumors (GCTs), which compose 70 to 80 percent of all pineal region tumors in Japan and Korea, for example. In the United States, the incidence of intracranial GCTs is highest in individuals with Asian/Pacific Island ancestry in the 10- to 29-year age group, suggesting that underlying genetic susceptibility may play a role in the etiology of these tumors.

Pineal tumors are substantially more common in males. In an analysis of 633 cases from the Surveillance, Epidemiology, and End Results (SEER) database over a 32-year period, pineal tumors were three times more common in males than females. In those with GCTs, the male predominance was approximately 12:1.

Types of Pineal Tumor

Tumors of the pineal gland may be one of these types:

Pineocytoma: These are slow-growing (grade I or II). These tumors usually appear between the ages of 20 and 64. But they can happen to a person at any age. People with pineocytomas tend to have a good outcome.

Pineal parenchymal tumor: These are intermediate-grade (grade II or III). Pineal parenchymal tumors and papillary pineal tumors may happen at any age.

Papillary pineal tumor: These are intermediate-grade (grade II or III).

Pineoblastoma: These are very rare, aggressive, and fast-growing (grade IV). They’re almost always cancer. These tumors most often affect people under 20 years of age.

Mixed pineal tumor: These are a combination of slow- and fast-growing cell types

Risk factors

Individuals with inherited genes possess a higher risk for developing tumors like Li-Fraumeni syndrome, von Hippel-Lindau disorder, neurofibromatosis, and retinoblastoma. Individuals working at rubber and chemical industries can also be at risk for tumors. Previous radiation treatment for head and neck cancers makes it a risk factor for pineal tumors.

Causes of Pineal Tumor

The precise cause of most pineal region tumours is not yet understood.

However, people living with an inherited genetic disorder called bilateral retinoblastoma are more likely to develop a pineal region tumour called pineoblastoma than people without this condition.

Pineal Tumor symptoms

Pineal region tumours originate from deep within the centre of the brain, close to the third ventricle (one of the large fluid filled spaces). This means that patients often experience increased pressure inside the skull due to a build-up of cerebrospinal fluid (CSF), a condition known as hydrocephalus.

Signs and symptoms of pineal region tumours may include:

• Headaches
• Nausea and vomiting
• Unusual eye movements or difficulty controlling the eyes: in particular, a characteristic upward gaze palsy, known as Parinaud syndrome
• Poor balance, for example whilst walking
• Poor co-ordination (ataxia)
• Disruption of sleep patterns
• Seizures
• Memory issues
• Early puberty in children

Complications of Pineal Tumor

Complications may include a life-threatening increase in intracranial pressure, requiring emergency medical attention.

Surgical complication

The most common surgical complication was the new onset or the worsening of preoperative ocular movement disturbances.

Some common complications are extraocular movement dysfunction, ataxia, altered mental status as well as seizures, or hemiparesis. Some factors increased incidence of surgical complications include prior radiation treatment, severe preoperative neurologic symptoms, malignant tumor pathology, and invasive tumor characteristics.

Diagnosis and test

Your doctor will review your personal and family medical history. He or she will also ask about recent symptoms. You will have a physical exam, including a neurologic exam. Your doctor may test your reflexes and ask you to do simple things like touch your finger to your nose. Your doctor may shine a light in your eye to look for swelling of the optic nerve. This may be a sign of increased intracranial pressure.

If a doctor thinks you have a brain tumor, he or she will want to see images of your brain. You may need tests, such as:

MRI: MRIs use radio waves, magnets, and a computer to make detailed images of the brain and spinal cord. For this test, you lie still on a table as it passes through a tube-like scanner. If you are not comfortable in small spaces, you may be given a sedative before the test.

Biopsy: In a biopsy, a sample of the tumor tissue is removed and examined for type and grade.

Exam of the CSF for tumor cells and other substances.

Blood tests to measure levels of substances such as melatonin, and alpha-fetoprotein.

You may first see your primary doctor. He or she may then refer you to a doctor that specializes in brain problems. This may be a neurologist, neurosurgeon, or neuro-oncologist. Your doctor can help you understand your pathology report. The report tells the size, location, type, grade, and other information about your tumor.

Treatment and medications

The main treatments for pineal region tumours include surgery, radiotherapy and sometimes chemotherapy. Your treatment depends mainly on the type of pineal region tumour you have. It also depends on:

• The size and position of the tumour
• The grade
• The symptoms you have.

Surgery

Surgery is often the main treatment for pineal region tumours.

Before having surgery to remove the tumour, you might need to have a build-up of cerebrospinal fluid (hydrocephalus) drained. This relieves any pressure in the brain. When the pressure has been relieved, you may have surgery to remove your tumour. Your surgeon will explain your operation and what to expect.

Radiotherapy and chemotherapy

Radiotherapy and chemotherapy may be used after surgery, depending on the type of tumour and how much of it has been removed. Radiotherapy uses high-energy rays to destroy the tumour cells. Chemotherapy uses anti-cancer drugs to destroy the tumour cells.

Radiotherapy and chemotherapy are very effective in treating some germ cell tumours, so surgery may not always be needed.

Radiotherapy may be used:

• As the main treatment
• As the main treatment, if surgery is not possible
• After surgery, if the tumour cannot be completely removed
• After surgery, to reduce the risk of the tumour coming back
• To treat the spinal cord, if there are signs the tumour has spread to the spine
• With chemotherapy, to treat some pineal region tumours.

A type of radiotherapy called stereotactic radiotherapy (SRT) can sometimes be used to treat pineal region tumours.

Chemotherapy is often used to treat germ cell tumours. It is also sometimes used to treat other types of pineal region tumours. This may be as part of a clinical trial. Your doctor will explain whether chemotherapy might be suitable.