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Other names: Pineal gland tumor, pinealoblastoma
Pineoblastoma is a very rare tumor that develops in the pineal gland in the brain. The pineal gland is a tiny structure deep within the brain. The main function of the pineal gland is to release melatonin, a hormone that controls sleep. It also influences the release of certain hormones from the pituitary gland.
The pineal gland is part of the endocrine system. It is located near the center of the brain. The pineal gland is tiny, about the size of a grain of rice. Its main job is to produce the hormone melatonin. The pineal gland receives nerve signals that depend on light perceived by the eye. Darkness causes the release of melatonin. Melatonin helps to regulate the body’s sleep/wake cycles. Melatonin also helps to control certain reproductive hormones including luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones are important for reproductive function.
Pineoblastoma is most common in children and young adults. However, these tumors account for less than 1% of childhood brain tumors. About half of tumors that occur in the pineal gland are pineoblastomas. Other tumors that can occur in the pineal gland include germ cell tumors, gliomas, and benign pineal parenchymal tumors. Pineoblastomas are very similar in histology to embryonal tumors such as medulloblastoma that occur in other locations.
Pineoblastomas can occur at any age. However, they are most common in children ages 10 and younger. In most cases, the cause of pineoblastoma is unknown. Rarely, pineoblastoma can occur in children with bilateral retinoblastoma, a cancer associated with a change in the gene RB1. The condition is also seen in patients with DICER1 syndrome.
Signs and symptoms of pineoblastoma depend on the tumor size and spread to other parts of the brain. Often, the tumor presses on the aqueduct in the brain. This causes cerebrospinal fluid to build up (hydrocephalus) and puts pressure on the brain.
Pineoblastoma symptoms may include:
As the tumor grows, it may block the normal flow of cerebrospinal fluid. This causes a buildup of fluid within the brain known as hydrocephalus. The fluid causes the ventricles to widen and increases pressure on the brain (intracranial pressure). Many of the symptoms of tumors in the pineal region are due to the increased pressure against brain tissue.
Doctors test for pineoblastoma in several ways.
There is no standard staging for pineoblastoma. However, doctors may classify the tumor by spread of disease. This tumor may spread through the cerebrospinal fluid in 10-20% of cases. It rarely spreads to other parts of the body outside the central nervous system.
Patients with evidence of disease spread are considered to be high risk. Additional risk factors include bulky residual disease after initial surgery, and younger age (less than 3 years old).
Optic pathway tumors are grouped by how they look under the microscope. The more abnormal tumor cells look, the higher the grade. Pineoblastomas are high-grade (grade IV) tumors.
Surgery to treat pineoblastoma is complex. The pineal gland is located deep within the brain, and the region has many blood vessels. However, successful removal of the tumor (gross total resection) is associated with better chance for recovery.
Factors that affect prognosis include:
Survival rates for pineoblastoma are estimated to be between 60-65%.
Treatment for pineoblastoma depends on several factors including the size and location of the tumor and the child’s age. The main treatments for pineoblastoma are surgery, chemotherapy, and radiation therapy. Treatment protocols are often similar to those used for medulloblastoma.
Because of the tumor location and the risk to nearby blood vessels, surgery is difficult. Surgery is used to remove as much of the tumor as possible. In some cases, patients with pineoblastoma will have surgery to place a shunt or to create an opening in the floor of the third ventricle (third ventriculostomy) in the brain to keep fluid from building up (hydrocephalus).
A shunt is a small tube that drains cerebrospinal fluid (CSF) so that the fluid can be removed from the brain. Excess fluid causes increased intracranial pressure and can cause many of the symptoms associated with pineal gland tumors. The shunt may be temporary or permanent.
Radiation therapy is often used after surgery for pineoblastoma. The dose and extent of radiation therapy depends on the presence or absence of disease spread and patient age. In general, for patients older than 3 years of age, radiation directed towards the entire central nervous system (craniospinal irradiation) with a higher dose (boost) at the primary tumor site is delivered. Late effects due to radiation can potentially occur and need to be monitored.
Chemotherapy is often used along with radiation therapy and surgery. In very young children, chemotherapy may be used to help delay radiation until the child is older.
Periodic surveillance with magnetic resonance imaging is used to monitor patients after completion of treatment. Follow-up should focus on early detection and intervention for potential neurological, cognitive and endocrine complications.
Patients who receive radiation therapy to the pineal gland are at risk for long-term endocrine problems including pituitary gland dysfunction (hypopituitarism). Ongoing monitoring of hormone levels is important, and patients may need medicines including hormone replacement.
The pituitary gland is called the “master gland” because it is responsible for many hormones and control of other glands. Low pituitary function can lead to a number of problems. These problems may include delayed growth, fatigue, and fertility problems.
Reviewed: June 2018