Definition and Overview
The pituitary gland is a highly important gland as it secretes hormones that carry messages from one cell to another to sustain various bodily functions. It also controls other hormone glands in the body including but not limited to the thyroid and adrenal glands as well as testicles and ovaries.
Neoplasm, on the other hand, is a medical term that refers to a benign or malignant (cancerous) tumour caused by certain DNA mutations that make cells grow and divide rapidly.
Most tumours found in the pituitary glands are benign or noncancerous (pituitary adenoma). However, a very small number are malignant, which means that they have the tendency to invade nearby tissue and structures and affect pituitary gland function. If left untreated, cancer cells can also spread (metastasise) to distant organs.
Most neoplasms of the pituitary glands are found in the anterior pituitary, which is responsible for making several hormones that control other endocrine glands. These include growth hormones (somatotrophin), thyroid-stimulating hormones (thyrotropin or simply TSH), adrenocorticotropic hormones (corticotrophin or simply ACTH), follicle-stimulating hormones (FSH), luteinizing hormones (LH), and prolactin. Tumours found in cells that make any of these hormones can produce more hormones than the body requires, leading to the development of various symptoms. For example, if the tumour produces too much thyroid hormones, the patient will suffer from hyperthyroidism which symptoms include weight loss, anxiety, sleep problems, excessive sweating, rapid heartbeat, nervousness, and hand tremor.
Causes of Condition
What causes pituitary tumours remains unknown. However, a small percentage is associated with multiple endocrine neoplasia 1 (MEN 1), Carney complex, and familial acromegaly. So far, there is no evidence to suggest that environmental factors play a role in the development of the condition.
Tumours on pituitary glands that do not produce hormones (non-functioning tumours) normally do not cause any symptoms. However, if they are left untreated and grow in size, they can put pressure on other surrounding structures. If the tumour puts pressure on the optic nerves, for example, the patient will suffer from vision loss. Large tumours can also cause hormonal deficiencies leading to sexual dysfunction, weakness, lack of menstrual periods, and unexplained weight gain or weight loss.
On the other hand, functioning tumours can cause a variety of symptoms when they overproduce certain hormones. ACTH tumours can cause high blood pressure, high blood sugar, bone weakening, acne, depression, anxiety, and irritability. Patients with growth hormone-secreting tumours, on the other hand, experience heart problems, misaligned teeth, excessive sweating, high blood sugar, and joint pain. Meanwhile, the overproduction of prolactin can cause erectile dysfunction, breast growth in men (gynaecomastia), loss of sex drive, and low sperm count.
Who to See and Types of Treatments Available
Because pituitary tumour symptoms are not very specific and can also be produced by other types of illnesses, many patients remain undiagnosed until they undergo imaging tests, such as magnetic resonance imaging (MRI) or computed tomography (CT) scan for an unrelated condition. The abnormal growths are also often accidentally found when patients with vision problems undergo vision testing.
Treatment options for pituitary tumours depend on whether the tumour is benign or malignant, its size, if it is functioning or non-functioning, and if it causes symptoms.
If the tumour is not causing other problems, doctors do not provide any form of treatment but require patients to undergo periodic testing to see if the tumour is growing or if the condition is progressing. In the field of medicine, this is simply referred to as watchful waiting.
Meanwhile, patients with functioning tumours are prescribed with medications that block excess hormones to provide symptoms relief. In some cases, these medications help shrink tumours, eliminating the need for additional treatment such as surgery. However, the prolonged intake of such medications has various side effects including an increased risk of gallstones and liver damage.
Surgical procedures are performed if the tumour is pressing on optic nerves and causing vision problems. The procedure can be performed via traditional open surgery in which the tumour is removed through an incision in the upper part of the skull. This technique is ideal for complicated or huge tumours. On the other hand, small growths and malignant tumours that have not spread to nearby nerves and brain tissue can be removed through endoscopic transsphenoidal surgery. This is a minimally invasive technique that removes the tumour through the nose and sinuses. Since it is performed without the use of an external excision, patients enjoy shorter recovery time and minimal postoperative complications.
Radiation therapy is an alternative treatment if surgery is not possible or if medications fail to provide symptoms relief. In some cases, it is performed before (if the tumour is too big and has to be shrunk first) or after (if the tumour persists or recurs following a successful surgical removal) surgery. Methods of radiation therapy include:
Proton beam therapy – Uses sub-atomic particles to destroy cancerous cells with minimal damage to surrounding tissue. This is the treatment of choice for many clinicians in treating children whose brains are still developing. It is also ideal in patients whose tumour is very near the optic nerve as it helps minimise serious complications.
External beam radiation – Delivers high-energy x-ray or electron beams to the tumour from outside the patient’s body. With careful treatment planning, this option can also spare surrounding normal tissue.
Gamma knife stereotactic radiosurgery – Uses specialised equipment to deliver radiation beams to the tumour without an incision. It decreases the risk of damage to normal tissue because the radiation beams it delivers is the size and shape of the tumour. The procedure is proven effective in relieving pituitary gland tumour symptoms, preventing tumours from reproducing, and shrinking both benign and malignant tumours within months.
Loeffler JS, et al. Radiation therapy of pituitary adenomas. http://www.uptodate.com/home.
Martinkova J, et al. Impulse control disorders associated with dopaminergic medication in patients with pituitary adenomas. Clinical Neuropharmacology. 2011;34:179.
Pituitary tumors treatment — for health professionals. National Cancer Institute. http://www.cancer.gov/types/pituitary/hp/pituitary-treatment-pdq#section/all.