A craniopharyngioma is a non-cancerous tumour growing above the pituitary gland. These slow growing tumours gradually invade into surrounding areas of the brain, damaging these tissues and causing compression-related symptoms.
Craniopharyngiomas look similar to a cyst and contain a dense, oily fluid as well as calcium deposits. The tumour is composed of embryonic pituitary gland cells, including ‘tooth forming’ cells, which produce an enamel protein leading to the calcium deposits.
Craniopharyngiomas are rare. They account for about 1% of brain tumours in adults. In Australia, about 450 people are living with the condition, with half aged less than 16 years. This type of tumour is also referred to as a Rathke pouch tumour, hypophyseal duct tumour or adamantinoma.
We are yet to understand fully what causes craniopharyngiomas, but it is believed that they begin developing early in life – while you’re being formed inside your mother. During embryonic development, two separate areas of the growing head (an area from the roof of the mouth and an area of the brain) fuse together to form the pituitary gland. However, possibly due to a genetic mutations or a disruption to this formation, if this fusion is incomplete a craniopharyngioma can occur.
Due to the slow growing nature of craniopharyngiomas, symptoms often don’t begin until the tumour is about 3 cm in diameter. At this size, the tumour begins compressing the surrounding tissues, such as the pituitary gland, optic nerve and hypothalamus. The compression can cause increased pressure in the brain and disrupt and/or damage the surrounding tissue. The hypothalamus is the size of an almond and is the part of the brain that links the rest of the brain to the pituitary. It produces hormones that control pituitary hormone production. The pituitary gland is part of the endocrine, or hormone system, in the body.
When the pituitary gland isn’t functioning, you develop hypopituitarism (a decrease in the pituitary gland function). Symptoms vary from person-to-person, but they commonly include – fatigue, weight gain or loss, constipation, constant infections, low sex drive (libido), impotence (men), loss of or irregular periods (women), infertility and hair loss.
A dull, continuous headache is the second most commonly reported symptom. It’s caused by pressure on the brain and a build-up of cerebrospinal fluid (called hydrocephalus). The third most common symptom, vision loss, is caused by pressure on the optic nerves. In addition, some people also experience a loss of growth hormone production. In adults the symptoms include loss of muscle mass and tone.
The most critical hormone to be deficient in is adrenocorticotrophic hormone (ACTH). This normally stimulates the production of the stress hormone cortisol from the adrenal glands. A prolonged cortisol deficiency can leave you feeling fatigued, dizzy, nauseous and vomiting. Untreated low cortisol will lead to an adrenal crisis. This is a medical emergency and needs immediate management.
Testing and Diagnosis
A craniopharyngioma presents with similar symptoms to other tumours in the pituitary region, including a Rathke’s cleft cyst. For this reason, your doctor will need to run several tests to make an accurate diagnosis. Expect to have blood tests to measure your pituitary hormone levels, vision tests and an MRI scan or CT scan of your brain to determine the size and location of your tumour. You may also have a neurological examination,
Generally, the combination of cysts and solid elements in a brain scan is indicative of a craniopharyngioma.
The first line treatment for craniopharyngioma is surgery. Postoperative radiation is generally favoured as it can be difficult to completely remove the tumour and even following complete removal, these tumours can reoccur.
The type of surgery will vary depending on the size and location of the tumour as well as its invasion into other structures. In some cases, the tumour can be drained to avoid major surgery or radiation alone may be recommended.
If there is a buildup of cerebrospinal fluid, a shunt may be inserted to relieve the pressure by draining the fluid from the brain to the stomach. This is done either before surgery or if the tumour regrows.
Hormone replacement medications are prescribed to treat hormone deficiencies caused by damage to the pituitary by the tumour.
An endocrinologist is essential for your long term care. The prognosis is good if the surgeon was able to completely remove your tumour. However, individual prognoses depend on age, the size of the tumour and the damage caused by the tumour prior to treatment.
Craniopharyngiomas reoccur in up to 75% of patients within two to five years, even if the tumour is fully removed. However, an early diagnosis and treatment can minimise the risk.
For this reason, you will need ongoing monitoring by a neurosurgeon. If the tumour regrows, further surgery and/or radiotherapy may be required.
The tumour can permanently damage your optic nerve and pituitary gland as well as cause neurological issues..
Want to know more?
See the Australian Pituitary Foundation fact sheets on:
This to be reviewed once all fact sheets are done.
You can also download the Pituitary Foundation’s booklet:
• Is it hypopituitarism? A patient’s guide to diagnostic testing
• Is it Craniopharyngioma? A patient’s guide to testing