What is a craniopharyngioma?
There are three different types of craniopharyngioma: adamantinomatous, papillary, and a mixed or transitional subtype that usually behaves like an adamantinomatous tumour, but actually contains a mixture of both forms of this tumour.
Craniopharyngiomas can be diagnosed in both adults and children, usually forming at the base of the brain near the pituitary gland. They can therefore have a large impact on hormone levels, as explained below.
This tumour type is mainly diagnosed in children, but can also occur in adults. They are often quite large tumours, potentially extending in all directions including into the third ventricle (one of the spaces in the middle of the brain that is usually filled with CSF fluid).
They contain many cystic (fluid filled) elements with some solid areas of tumour. Areas of calcification are found in around 90% cases, meaning that calcium has built up because the tumour is no longer able to regulate the movement of calcium in out of the damaged cells.
This subtype is found almost exclusively in adults. It is a more solid type of tumour with fewer cystic elements than an adamantinomatous craniopharyngioma, and calcification is rare.
Where do craniopharyngioma tumours occur in the brain?
They are usually found at the base of the brain, occurring anywhere along the hollow structure or “stalk” that connects the hypothalamus and the posterior pituitary gland.
What do the hypothalamus and pituitary gland control?
The pituitary gland is a small structure attached to the base of the brain behind the nose, and is about the size of a pea. It lies just below the eye in a small hollow in the skull, where it is protected by a part of the skull called the sphenoid bone.
Just above the pituitary gland lies the hypothalamus, which produces hormones that control when the pituitary produces and releases hormones of its own. Together they orchestrate the delicate balance of hormones made by glands throughout the body including thyroid, ovaries and testes. The pituitary gland directly produces hormones that control the function of certain organs such as the breasts, uterus and kidneys. The pituitary therefore influences many processes including growth, development, and reproduction.
A neuro-endocrinologist would therefore participate in the multi-disciplinary team that looks after somebody with this type of tumour, as they specialise in managing hormone balance.
How common are craniopharyngioma tumours?
Craniopharyngiomas represent 6%-13% of all paediatric brain tumours and 1-3% of all adult brain tumours.
Tumours diagnosed when the patient is between 5 and 15 years old are usually adamantinomatous craniopharyngiomas, whilst papillary craniopharyngiomas are found almost exclusively in adults.
However, adults can also be diagnosed with adamantinomatous craniopharyngiomas and there is a slight increase in incidence for this subtype amongst adults over 40 years old.
Adamantinomatous craniopharyngiomas are 3 to 9 times more common than papillary craniopharyngiomas.
Are craniopharyngioma tumours benign or cancerous?
Craniopharyngioma tumours are usually classified as grade 1, the most slow-growing (low grade) form of brain tumours.
What is the prognosis for craniopharyngioma tumours in the brain?
This is largely dependent on the size and position of the tumour, and hence the side effects that the tumour causes. However, the prognosis is generally very good with progression-free survival rates for adults of around 71.8% at 5 years and 63.6% at 7 years.
Children are often cured of their tumour, but the long-term effects of treatment may cause life shortening side effects.
Unfortunately these tumours do tend to recur after treatment in around one third of patients. Complete removal using neurosurgery or radiosurgery and the use of radiotherapy afterwards reduces the likelihood of these tumours recurring, but long-term regular follow-up using MRI scans is advised.
What are the symptoms of craniopharyngioma tumours?
Because the pituitary gland has such varied functions, a tumour can be difficult to diagnose because the symptoms will differ between patients. The symptoms are often due to changes in the levels of the hormones that the gland produces, and there is a range of reasons why those hormone levels may fluctuate and cause symptoms, hence delaying the diagnosis of a tumour.
Symptoms caused by hormonal fluctuations include:
- Delayed puberty in children
- Changes in menstrual periods or early menopause in women
- Increased or decreased sexual drive
- Extreme growth spurts in both children and adults, particularly of either hands or feet
- Unexplained weight gain or loss, sometimes combined with a loss of appetite
- Extreme tiredness and/or listlessness
- Personality changes such as hostility, depression, anxiety
- Low blood pressure
- Loss of muscle mass in adults
- Easy bruising of the skin, often combined with muscle weakness
- Changes in the sense of smell
- Vision problems such as blurring, double vision, loss of peripheral vision
- Nausea and vomiting
- Diabetes insipidus, caused by problems with a hormone called vasopressin (AVP), commonly known as antidiuretic hormone (ADH). Symptoms are extreme thirst and/or excessive urination
If the tumour is large enough to press upon surround brain tissue, the symptoms may be very similar to those of other brain tumours found in this part of the brain.
How is a craniopharyngioma tumour diagnosed?
The most reliable way to diagnose any kind of brain tumour is initially by an MRI scan and then by taking a biopsy (a small sample of the tumour, removed during neurosurgery) for analysis in a laboratory.
What causes a craniopharyngioma tumour in the brain or spine?
The causes of a craniopharyngioma tumour are not known, so unfortunately there are no proven ways to prevent them from occurring.
Treatment options for craniopharyngioma tumours
Neurosurgery is usually the first line of treatment for these tumours.
A ventriculoperitoneal (VP) shunt is a small medical device that may also be inserted during the first surgical operation. This works to reduce the build-up of cerebrospinal (CSF) fluid within the ventricles of the brain, which causes a condition known as hydrocephalus. The shunt helps the CSF fluid to flow out of the brain, hence reducing pressure on the brain and helping to relieve symptoms.
Neurosurgery is usually followed by radiotherapy, and this will always be the case if any tumour is left behind after the surgery.
Hormone replacement therapy is also likely to be included in the management of this tumour type.
New treatments may be available to some patients in the context of clinical trials. For example, some tumours in this group have been found to have a BRAF V600E mutation and to respond well to BRAF/MEK inhibitor drugs, so clinical trials are underway to clarify their potential use.
How will we find a cure for craniopharyngioma tumours?
Research we are funding across all of our dedicated Research Centres will help lead towards finding a cure for a wide range of brain tumours.
The team of research and clinical experts in our Research Centre at Imperial College, London, are studying the way in which the ketogenic diet works in brain cancer, which may have the potential to influence a wide range of brain tumours.
Pioneering research at our Brain Tumour Research Centre at Queen Mary University of London is focused on using GBM stem cells to help develop unique, patient-specific treatments. Their findings are expected to translate into other types of adult and paediatric brain tumours.
Our team at the University of Plymouth Low-Grade Brain Tumour Research Centre are researching a number of molecular pathways that influence immune system function, tumour metabolism and tumour growth in a range of low-grade brain tumours in children and adults.
We also fund BRAIN UK at Southampton University, the country’s only national tissue bank registry providing crucial access to brain tumour samples for researchers from all clinical neuroscience centres in the UK, effectively covering about 90% of the UK population, and an essential component in the fight to find a cure for all types of brain tumours.