What is a craniopharyngioma?
A craniopharyngioma is a benign, slow-growing tumour made up of solid parts and, in children, most commonly of cysts. The solid parts contain calcium, and the cysts are full of fluid. The tumour is located in the central part of the brain, in and around the area of the pituitary gland. It is also near other important parts of the brain such as the hypothalamus, the optic pathway, and the third ventricle. Symptoms begin when it starts to grow and affect surrounding areas of the brain.
Two small but important parts in the brain — the hypothalamus and pituitary gland — are likely to be affected. These areas release important hormones; chemicals that regulate growth, sexual development, sleep patterns, the body’s temperature, water balance, appetite, blood sugar levels, and the way the body uses fat (fat metabolism). The optic pathway, which is involved in vision, may also be affected. Hormone replacement will probably be needed if the tumour or treatment affects the hypothalamus and/or pituitary gland.
There are different approaches to treatment based on the child’s age and on features of the tumour. Surgery, intracystic therapy and possibly radiation therapy at the site of the tumour, may be used for treatment. Currently, targeted therapies are being investigated in clinical trials to see how effective they are at treating craniopharyngiomas.
What are the symptoms of a craniopharyngioma?
Common symptoms of craniopharyngiomas are:
- headaches
- vomiting
- problems with vision
The tumour can press on the hypothalamus and pituitary gland, which affects their ability to release hormones. Because hormone levels are changed, the child with a craniopharyngioma may experience poor growth, delayed puberty (or in rare cases, early puberty), and appetite changes. A child may also develop diabetes insipidus, which causes intense thirst and increased need to urinate (pee).
Other symptoms can include:
- fatigue
- sleepiness in the daytime
- waking at night
- significant weight gain
- behaviour changes
- memory problems
What causes a craniopharyngioma?
The exact cause of craniopharyngiomas is unknown. It is believed that it grows from cells that normally disappear during embryonal (fetal) development. Because these cells did not disappear, they may give rise to form a craniopharyngioma.
There is no way to predict that a child will get a tumour. Nobody is to blame if a child develops a craniopharyngioma.
Researchers have been studying whether environmental factors, such as food or chemicals, can cause brain tumours. At the moment, there is no definite proof that there is a connection.
How many other children have craniopharyngiomas?
Craniopharyngiomas account for about 3% to 5% of brain tumours in children. They are usually found in children aged 5 to 10.
How is a craniopharyngioma diagnosed?
Doctors and other health-care professionals will use well-established diagnostic tests to see if a brain tumour is causing your child’s symptoms. These tests will include a physical examination, and brain scans such as magnetic resonance imaging (MRI) or computerized tomography (CT) scan, which will identify the presence of a tumour.
A sample of the tumour may be taken at the time of surgery to confirm the diagnosis. This is called a biopsy. In craniopharyngioma, the engine oil-like cyst fluid of the tumour is pathognomonic (characteristic) for craniopharyngioma and not seen in any other brain tumours. If a small piece of tumour is removed, it will be sent to a doctor called a pathologist. They will look at the tumour under a microscope to determine the exact type of tumour. If the tumour contains the engine oil-like cyst fluid, then it is a craniopharyngioma.
How is a craniopharyngioma treated?
Once the health-care team has a clear understanding of what is causing your child’s symptoms — usually after surgery — a meeting with the team will be set up to talk about results and the treatment plan. Remember that it is helpful to bring something to take notes with, such as a paper and a pen or laptop, at each meeting with this team. It is important to have the child’s primary caregivers in this meeting, for example both parents.
The treatment team may include a neurosurgeon, a neuro-oncologist, endocrinologist, radiation oncologist, a nurse practitioner or nurse, and a social worker. During the meeting, they will explain which doctor is responsible for your child’s treatment, and the roles of everyone who is there. Other team members may be involved such as a dietitian, pharmacist, occupational therapist, and physiotherapist, depending on your child’s needs. Every team member has their role in your child’s care, and everyone works together to make your child feel better.
The doctor will explain the type of tumour that your child has, based on what the team has learned through diagnostic testing. You will learn the expected effect this tumour will have on your child in the upcoming months and years, based on what is known about the tumour. This is called the prognosis.
The team may talk about placing your child on a protocol, which is a treatment plan for craniopharyngioma. You will need to consent (agree) to the plan for the treatment to begin. Teenaged patients may be asked for their consent as well.
There are different approaches to treatment based on the child’s age and on features of the tumour.
Before you agree to the treatment offered, it is important that you understand what to expect and feel comfortable with your decision.
Surgery when the tumour is mostly solid
Surgery can be difficult and can cause many problems because these tumours "stick" to nearby tissues. Doing a resection (surgical removal of the tumour) safely will depend on the location and the size of the craniopharyngioma. Surgeons aim to remove only those parts of the tumour that are safely resectable without causing harm. Radiation therapy may be used to treat the remaining tumour if it continues to grow. Radiation can be given as photon or proton therapy; currently proton therapy is available in the United States for Canadians.
Surgery when the tumour has cysts
If the craniopharyngioma is mainly cystic, draining the fluid in the cyst will reduce pressure quickly. The surgeon will make a small hole (burr hole) in the skull and insert a tube into the cyst to drain it and/or they may put a permanent drain in called an Ommaya reservoir. This can be followed by injection of interferon directly into the cyst to help decrease the fluid being made by the walls of the cyst and to make the cyst smaller. Sometimes several treatments with interferon are needed to dry the cyst.
Interferon is the name of the drug administered into the cyst. This drug helps to stop the cyst from producing fluid and eventually helps to shrink the cyst. Side effects of interferon include joint pain, fatigue, and flu-like symptoms.
Some treatment centres may use a radioactive substance such as phosphorus or yttrium. It is planted in part of the cyst to help shrink it.
In some cases, the craniopharyngioma may block the cerebrospinal fluid (CSF) pathway. This causes hydrocephalus, a build-up of fluid in the hollow channels of the brain called the ventricles. The surgeon may need to do a small operation to place a ventriculo-peritoneal shunt (VP-shunt) so the CSF can flow from the ventricles to the abdominal cavity where it is absorbed.
Intracystic therapy for craniopharyngiomas
Some cystic craniopharyngiomas can be treated with local administration of interferon. This means that the agent is given directly into the cyst. It is also referred to as intracystic therapy. An Ommaya reservoir is used for intracystic therapy.
An Ommaya reservoir is used when interferon should go directly to the craniopharyngioma cyst. An Ommaya reservoir is implanted directly under the scalp which is connected to a thin tube (catheter) going into a cyst. The reservoir is inserted during surgery.
Before starting intracystic therapy, a "permeability study" (a CT scan with contrast given into the Ommaya catheter) is done to rule out any leakage out of the cyst.
While your child is getting intracystic therapy, they will have regular checkups. It is important to tell the treatment team about all of the changes or symptoms your child has while at home. The treatment team will ask about your child’s appetite, daily activities, pain, headaches, and vision problems. There will also be a physical exam during regular checkups.
Clinical trials
Many doctors are trying to make cancer treatments more successful. They can do this by studying different types of treatment, in clinical trials. Your child’s doctor may ask if you would like your child to participate in a clinical trial. You will have to sign an informed consent form for your child to participate in a trial. The health-care team will explain the differences between being on a clinical trial and getting the standard treatment.
Additional supports
When you meet with the treatment team, you may also be told about resources available to support your child, you and your other children during treatment and recovery. You will be encouraged to think about any questions concerning the diagnosis and the treatment plan.
What is the outcome for a child with a craniopharyngioma?
A child with craniopharyngioma has a very good chance of surviving. After 10 years, about 90% of children with a craniopharyngioma will survive.
However, there is a large range of possible challenges. Some children may have very few long-term effects. Others can have very serious long-term effects that will have a significant impact on their lives. Often, lifelong hormone replacement is needed because the tumour, surgery and/or radiation therapy has damaged the pituitary gland or the hypothalamus.
Some long-term effects that may occur are diabetes insipidus, obesity, sleep problems, memory problems, and mood swings.
Follow-up care may be very complex as it may require involvement of many doctors including the following:
- Neurosurgeon
- Neurologist
- Oncologist
- Endocrinologist
- Psychiatrist
- Neuropsychiatrist
Children ideally should be followed up in a comprehensive craniopharyngioma clinic.
Recurrence of craniopharyngiomas
If a craniopharyngioma recurs (grows back) there are different approaches to treatment. Because a craniopharyngioma may be made up of cysts and solid tumour, the recurrence can happen in either. The treatment will depend on the type of recurrence.
If the solid tissue grows back, either surgery or radiation may be used as treatment. In some cases, surgery and radiation may both be used.
If the cysts grow back, intracystic therapy may be needed using interferon. Sometimes, repeated treatment courses with interferon are needed. Targeted therapies (e.g. MEKinhibitor) are being investigated in clinical trials for efficacy.
