Endolymphatic sac tumours (ELST) is a very rare group tumour that develops in the endolymphatic sac, which is a balloon shaped structure in the inner ear. These tumours are often classified as benign (non-cancerous), however they can become malignant (cancerous).
The endolymphatic sac and duct are filled with fluid that surrounds and protects other structures in the inner ear, which affect hearing and balance. They are responsible for releasing fluid to regulate pressure and volume in the inner ear, removing excess fluid and waste products from the inner ear, and regulating the immune response in the inner ear.
ELSTs are often associated with Von Hippel-Lindau (VHL) syndrome, which is a rare genetic disorder that causes the development of multiple benign (non-cancerous) and malignant (cancerous) tumour throughout the body. For more information on VHL, please refer to the Rare Cancers Australia Von Hippel-Lindau page.
ELSTs are often diagnosed equally between the sexes, and are often diagnosed around 30 years of age. However, anyone can develop this disease.
Treatment
When cancers are detected, they are staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body), and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, as ELSTs are considered benign, these tumours are generally considered low-grade and not staged.
Once your tumour has been diagnosed, your doctor may recommend genetic testing, 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 is dependent on several factors, including tumour size, age, stage of disease and overall health.
Treatment options for ELSTs may include:
- Surgery, potentially including:
- Mastoidectomy (removal of diseased or dead cells in the air-filled spaces of the mastoid bone of the skull).
- Temporal bone resection (removal of affected portion of the temporal bone of the skull).
- Nerve repair surgery (used to repair any nerve damage that occurs as a result of the tumour or of any surgery – may not be available for all patients).
- Radiation therapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Risk factors
Because of how rare ELSTs are, there has been limited research done into the risk factors of this disease. However, there has been a definitive link between the development of ELSTs and patients who have been diagnosed with VHL.
Early symptoms
ELSTs may appear asymptomatic in the early stages of disease. As the tumour progresses (often rapidly), some of the following symptoms may appear:
- Hearing loss.
- Tinnitus (ringing in one or both ears).
- Dizziness.
- A feeling of pressure in the ear.
- Facial paralysis (rare).
Patients with VHL may experience additional symptoms depending on the tumours present.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have haemangioblastoma, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Genetic testing
In addition to guiding treatment, genetic testing can be used to help diagnose certain conditions. ELSTs have been linked to mutations in the VHL gene, which changes specific protein functions. These changes can lead to cell abnormalities and, in extreme cases, cancer. Your doctor may perform genetic testing to better understand your condition.
Neurological examination
A neurological examination assesses sensory and motor functions, and can generally be done in your GPs office. The doctor may check your vision, hearing, balance, coordination, strength, and reflexes, depending on the signs and symptoms you have described. Any problem that is detected in this exam can help determine which portion of the CNS needs further investigation.
Imaging & Blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), x-rays, bone scan and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and look for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
Once the location of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. This tissue will then be sent to the lab and analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early stage ELSTs have a good prognosis and survival rates. However, if the tumour has become malignant and/or has spread, the prognosis may not be as good, and there may be a higher risk of recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.