What is a pineal region tumour?
Pineal region tumours form in the pineal region of the brain, which is located deep in the centre of the brain in an area called the epithalamus, where the two halves of the brain join. They can form either within the pineal gland itself or in the surrounding area.
What is a pineal gland?
The pineal gland is a small, pinecone shaped gland found deep in the centre of the brain.
The function of the pineal gland is not fully understood, but it is well known for regulating our circadian rhythms. One way that it does this is to produce and regulate melatonin, a hormone that helps to regulate our sleep patterns.
The pineal gland also helps to regulate female hormone balance, and therefore influences female fertility and menstrual cycles.
How common are pineal region tumours?
As a group, pineal region tumours are diagnosed more often in children than adults, representing 3%-11% of all paediatric brain tumours, compared to less than 1% of brain tumours diagnosed in adults.
What types of brain tumour are classified as pineal region tumours?
Pineal region tumours are grouped into four tumour types, defined in the 2016 report by the World Health Organisation (WHO) entitled “Classification of Tumours of the Central Nervous System (CNS).” However, other tumours found in the pineal region are germ cell in origin and include germinomas, embryonal cell tumours and choriocarcinomas.
All brain tumours are classified based on their characteristics identified by histology (how they look under a microscope), and by molecular profiling (information gained via genetic testing on a sample of the tumour removed during a biopsy).
Pineocytoma
- Pineocytomas develop from pinealocyte cells and/or their precursors (the stem and progenitor cells from which pinealocytes form). Pinealocytes are the main cells in the pineal gland that produce the hormone melatonin.
- Classified as WHO grade 1, pineocytomas are relatively easy to remove using neurosurgery due to having a clear boundary where the tumour ends and healthy tissue begins. In such cases, they are considered a benign tumour.
- Pineocytomas are often diagnosed when they are less than 3cm diameter.
- Pineocytomas account for 14-30% of all pineal region tumours.
- Pineocytomas can develop at any age, but occur most often in adults between 20 and 60 years of age.
- Pineocytomas are slightly more frequently diagnosed in females than in males.
Pineal parenchymal tumour with intermediate differentiation (PPTID)
- Pineal parenchymal tumours with intermediate differentiation (PPTIDs) develop from pinealocyte cells and/or their precursors (the stem and progenitor cells from which pinealocytes form). Pinealocytes are the main cells in the pineal gland that produce the hormone melatonin.
- Classified as WHO grade 2 or grade 3, PPTIDs tend to return after treatment and are classified as a low-grade or slow-growing form of cancer.
- PPTIDs were only recognised by the World Health Organisation (WHO) as a unique sub-group of pineal region tumours in 2007, so prior to this date tumours now classified as a PPTID may have been called “atypical pineocytomas,” “ malignant pineocytomas” or “mixed pineocytoma–pineoblastomas.”
- PPTIDs account for 20-62% of all pineal region tumours.
- Although these tumours can be diagnosed at any age, they are most commonly seen in middle age adults (20-70 years of age).
- PPTIDs are slightly more frequently diagnosed in females than in males.
Papillary tumour of the pineal region (PTPR)
- PTPRs develop from cells called ependymocytes that line the ventricles of the brain and the central canal of the spinal cord, rather than from cells of the pineal gland itself. Ependymocytes are a form of ependymal cell, which is one of the four main types of glial cells. Glial cells give rise to the largest group of brain tumours called gliomas.
- Classified as WHO grade 2 or grade 3, PTPRs tend to return after treatment and are classified as a low-grade or slow-growing form of cancer.
- Papillary tumours of the pineal region (PTPRs) occur more often in adults than in children, but have been reported in patients ranging from 1 to 70 years, with the average age being around 31 years.
- PTPRs occur equally in both males and females.
Pineoblastoma
- Pineoblastomas develop from pinealocyte cells and/or their precursors (the stem and progenitor cells from which pinealocytes form). Pinealocytes are the main cells in the pineal gland that produce the hormone melatonin.
- Classified as WHO grade 4, pineoblastomas are fast-growing, malignant tumours that tend to invade nearby tissue within the brain and spine, carried in the cerebrospinal fluid (CFS).
- There is an association between pineoblastomas and hereditary retinoblastoma, a tumour that forms in the eye. Such patients tend to be diagnosed when they are around 1 year old. This combination of a retinoblastoma and pineoblastoma is called trilateral retinoblastoma.
- Pineoblastomas account for 24-50% of pineal region tumours.
- Pineoblastomas are most likely to be diagnosed in people under 20 years old.
- Pineoblastomas are slightly more likely to be diagnosed in females compared to males.
Are pineal region tumours benign or cancerous?
The degree of malignancy depends upon the grade of the tumour.
A grade 1 pineal tumour that is easily removed would be classed as benign.
A grade 2 or 3 pineal tumour tends to return after treatment and would be classified as a low-grade or slow-growing form of cancer.
A grade 4 pineal tumour would be classed as an aggressive or malignant form of fast-growing cancer.
The most aggressive forms of pineal region tumours tend to spread throughout the central nervous system (CNS), which consists of the brain and spine, but are highly unlikely to spread to other parts of the body.
What is the prognosis for a pineal region tumour?
The survival time for each patient with a pineal region tumour is dependent upon the type of tumour that they have. A grade 1 tumour may be cured, whilst a grade 4 tumour is much more challenging to treat.
The more of the tumour that can be removed using neurosurgery, the longer the patient is likely to survive.
For grade 1 pineocytomas, the 5-years survival rate is as high as 86%. Local recurrent and occasionally cerebral spinal fluid (CSF) metastases are reported, but rare.
Unfortunately, progression to a grade 4 pineoblastoma occurs in almost 75% of papillary tumours of the pineal region (PTPRs) that are originally diagnosed as grade 2 or 3, so the prognosis for these tumour types is very dependent upon how the tumour responds to treatment and whether or not it progresses. The prognosis is unclear due to historical issues around how these tumours were classified, and will be somewhere between a pineocytoma and a pineoblastoma.
Grade 4 pineoblastomas are rare but unfortunately they are very challenging to treat. For children under 4 years old, the 5 years overall survival rate is as low as 8.3%. For children over 4 years old, the 5 years overall survival rate rises to 66.7%. They are so rare in adults that no separate prognosis for adults has been clarified.
What are the symptoms of pineal region tumours?
Pineal region tumours originate from deep within the centre of the brain, close to the third ventricle (one of the large fluid filled spaces). This means that patients often experience increased pressure inside the skull due to a build-up of cerebrospinal fluid (CSF), a condition known as hydrocephalus.
Signs and symptoms of pineal region tumours may include:
- Headaches
- Nausea and vomiting
- Unusual eye movements or difficulty controlling the eyes: in particular, a characteristic upward gaze palsy, known as Parinaud syndrome
- Poor balance, for example whilst walking
- Poor co-ordination (ataxia)
- Disruption of sleep patterns
- Seizures
- Memory issues
- Early puberty in children
Read more about symptoms of a brain tumour here.
How is a pineal region 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 pineal region tumour?
The precise cause of most pineal region tumours is not yet understood.
However, people living with an inherited genetic disorder called bilateral retinoblastoma are more likely to develop a pineal region tumour called pineoblastoma than people without this condition.
Read more about the causes of brain tumours here.
Treatment options for pineal region tumours
The first line of treatment for pineal region tumours is usually surgery. Luckily, the majority of pineal tumours can be accessed using minimally invasive keyhole surgery that passes over the cerebellum situation at the back and base of the brain.
Surgery is likely to be followed by radiotherapy and chemotherapy.
Discover more about neurosurgery, radiotherapy and chemotherapy here.
New treatments may be available to some patients in the context of clinical trials. These may include immunotherapy, novel combinations of existing chemotherapy drugs, and emerging drugs that target the specific genetic mutations of individual tumour types.
For more information about clinical trials, please click here.
How will we find a cure for pineal region 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.
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.
Scientists at our Research Centre in the University of Portsmouth are looking at repurposing drugs for a number of different types of brain tumours. They are also studying mitochondria, exploring ways to ‘shut down’ these ‘batteries’ that supply energy to the 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.
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 pineal region brain tumours.