Craniopharyngiomas, also known as Rathke’s pouch tumour or craniopharyngeal duct tumours, are rare tumours that develop in the sellar and parasellar regions of the brain. It is classed as a type of central nervous system (CNS), which is made up of the brain and spinal cord.
The sellar and parasellar regions of the brain are complex, and hold and support many important structures in the brain. The sellar region of the brain is located in the centre of the cranial base (bottom portion of the skull), and is made up of the pituitary gland, a primary endocrine gland of the body, and the sella tunica, a bony pouch that the pituitary gland sits in. The parasellar region holds cavernous sinuses, suprasellar cistern, hypothalamus, and ventral inferior third valve.
In most cases, craniopharyngiomas are benignnot cancerous, can grow but will not spread to other body parts and carry a good prognosisto predict how a disease/condition may progress and what the outcome might be. In very rare cases, the tumours can undergo a transformation and become malignant.
Craniopharyngiomas tend to be diagnosed in children between the ages of 5-14, or in adults over 50 years old. They are generally diagnosed equally between the sexes, and can develop in anyone at any age.
Types of Craniopharyngiomas
There are two primary types of craniopharyngioma, which are categorised by the types of cells they develop from.
Adamantinomatous Craniopharyngioma
Adamantinomatous craniopharyngiomas (ACP) are primarily found in children, and generally develop from cells in the craniopharyngeal duct. The craniopharyngeal duct is a bony channel that connects the bottom of the sella tunica to the nasopharynx (a structure in the upper most portion of the throat, behind the nose). ACPs can be solid or cystic (growth filled with liquid). They are often classified as grade I (or low grade) tumours, as they develop slowly and rarely spread. While they may have a high recurrence rate, they generally carry a good prognosis.
Papillary Craniopharyngioma
Papillary craniopharyngiomas (PCP) are a less common subtype of craniopharyngiomas that are more common in adults. They generally develop from cells in the anterior portion (or front) of the pituitary gland. PCPs can be solid or cystic, and are often classified as grade I tumours. While they may have a high recurrence rate, they generally carry a good prognosis.
Malignant Craniopharyngioma
In very rare cases, a benign craniopharyngiomas can undergo a malignant transformation and become cancerous. It is not clear what causes this transformation, but a potential link to previous radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells has been identified. Malignant craniopharyngiomas are not well understood, but are thought to develop more rapidly and are more likely to metastasise. The prognosis for malignant craniopharyngiomas may not be as good as benign craniopharyngiomas.
Treatment
When cancers are detected, they are staged and graded based on size, metastasis, and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, brain cancers are rarely staged, as they rarely spread to other parts of the body. Instead, they are generally graded from grades I-III.
Because of how rare craniopharyngiomas are, there is currently no standard grading system for this disease. Instead of grading, your doctor will recommend a treatment plan based on the following factors:
- Cancer location.
- Whether or not the cancer has metastasised.
- Your age.
- General health.
- Your treatment preferences.
Your doctor may also recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment options for craniopharyngiomas may include:
- Surgery to remove as much of the tumour as possible, potentially including a craniotomya surgical procedure involving the temporary removal of a portion of the skull to access the brain.
- Radiation therapy.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Hormone replacement therapymedication that increase the levels of certain hormones in the body.
- Targeted therapymedication that targets specific molecular features of cancer cells.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
Because of how rare craniopharyngiomas are, there has been limited research done into the risk factors of this disease. However, a potential link to previous radiation therapy has been identified, but more research would be required to confirm this.
Symptoms
The symptoms of a craniopharyngiomas are often related to the pressure that the tumour is putting on the brain, pituitary gland, and nearby nerves. They usually occur when the tumour reaches a certain size. General symptoms may include:
- Nausea and/or vomiting.
- Confusion.
- Mood swings.
- Behavioural changes.
- Fatigue.
- Balance difficulties.
- Polydipsiaabnormal or escessive thirst.
- Polyuriafrequent urination.
- Vision changes, potentially including:
- Blurred vision.
- Diplopiaseeing two images of a single object, also known as double vision.
- Loss of peripheral vision.
- Blindness.
- Persistent headaches.
Craniopharyngiomas can result in decreased hormone production which may cause additional symptoms:
- Delayed growth in children as a result of growth hormone (GH) deficiency.
- Follicle stimulating hormone (FSH) or luteinizing hormone (LH) deficiency, which may result in:
- Delayed puberty.
- Amenorrhea.
- Precocious puberty (rare).
- Adrenocorticotropic hormone (ACTH) deficiency, which may cause:
- Unexplainable weight loss/loss of appetite.
- Muscle weakness.
- Hypotensionlow blood pressure.
- Diarrhoea.
- Hypoglycaemialow blood sugar.
- Dilutional hyponatraemialow levels of sodium in the blood.
- Thyroid stimulating hormone (TSH) deficiency, which may cause:
- Fatigue.
- Lethargy.
- Menstrual changes.
- Forgetfulness.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have a craniopharyngioma, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Neurological examinationan assessment of sensory and motor functions, such as vision, balance and coordination.
- Endocrine studies.
- Imaging tests, potentially including:
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- PET (positron emission tomography) scana type of medical imaging that uses radioactive tracers to create detailed images of the body.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
