What is a Pineoblastoma?

A pineoblastoma is an aggressive, malignant brain tumor that originates from the pineal gland, a small organ located near the middle of the brain. A rare form of brain cancer, pineoblastomas account for only three to 10 percent of the total primary malignant brain tumors in children and adults. This type of tumor is usually seen in patients less than twenty years of age, and is most common in children 10 years-old and younger.

The pineal gland is a tiny endocrine organ that lies between the two hemispheres of the brain. Shaped like a pair of pine cones, the pineal gland produces the hormone melatonin, which helps regulate sleep patterns. More than 17 different types of benign and malignant tumors may arise in the pineal region of the brain. A pineoblastoma is one of the most common types of tumors in this area. The underlying cause of a pineoblastoma is currently unknown.

One of the most frequent results of a pineoblastoma is hydrocephalus, an increase in cerebrospinal fluid (CSF) pressure in the brain. This is often due to the tumor compressing the aqueduct of Sylvius, which is located next to the pineal gland. The aqueduct of Sylvius is a passage that allows CSF to exit the brain, where it is made. When the flow of CSF is blocked, the patient may experience symptoms typical of the condition, including visual problems, difficulties with memory, headaches, nausea with vomiting, and seizures.

Hydrocephalus can be a life-threatening condition that may require immediate surgical intervention. This can be achieved by the placement of a ventriculo-peritoneal shunt in one of the spaces in the brain containing the excess CSF, allowing it to drain into the abdomen. Another surgical technique to treat hydrocephalus is stereotactic third ventriculostomy, which creates a small hole at the bottom of the brain through which the CSF can drain.

Other common symptoms of a pineoblastoma are related to changes in the patient's vision. This is due to the tumor's proximity to the tectal region, which plays a key role in regulating eye movements. Patients with a pineoblastoma may, therefore, experience difficulty focusing on objects and may have double vision. Symptoms of a pineoblastoma that are unrelated to vision include changes in personality, weakness or loss of sensation on one side of the body, changes in weight or appetite, and fatigue or increased need for sleep.

Diagnosis of a pineoblastoma is most often made using magnetic resonance imaging (MRI), which can show the exact location and dimensions of the tumor. A computed tomography (CT) scan or MRI may also show the extent of the hydrocephalus. A lumbar puncture (lp), also known as a spinal tap, may be helpful to obtain a sample of CSF, as some pineoblastomas can excrete abnormal levels of certain hormones and chemicals, including Beta-HCG, AFP, and CEA, which may be detected in the CSF or blood. A surgical biopsy using a minimally invasive technique, such as endoscopy or stereotactic needle biopsy, may also be necessary to make a definitive diagnosis.

Pineoblastomas can be treated through surgical intervention. This can provide a cure, if the entire tumor is removed, or can help improve the prognosis by reducing the size of the tumor. Chemotherapy and radiation therapy, to which over 70 percent of pineoblastomas respond, are also often used as treatment.