What Is Pituitary Adenoma? Causes Of Pituitary Adenoma

What is the pituitary gland?

With a shape and size that resembles that of a pea, the pituitary gland is a small gland located just below the base of the brain – between the eyes and behind the nose. The area where this gland is located is also known as sella turcica or pituitary fossa. The pituitary is often referred to as the “master” gland because it’s responsible for controlling & regulating the secretion of most of the body’s hormones that control several other glands throughout the body.

What is a pituitary adenoma?

Pituitary adenomas are benign growths which tend to grow relatively slowly. Pituitary adenomas are considered to be the fourth most common intracranial tumor and also by far the most common disease that affects the pituitary gland. More often than not, these tumors originate from the anterior lobe of the pituitary gland. It also needs to be mentioned that in the majority of the cases, tumors in the pituitary gland are benign in nature, and in most cases, turn out to be pituitary adenomas.  For instance, 1 in 5 people have been estimated to have pituitary adenoma at some point in their life.

However, there have been cases of malignant tumors developing in the pituitary gland – although such instances are considered to be extremely far and few between. As per statistics, there have only been about 100 cases of malignant pituitary cancer reported in the medical literature till date which further goes to highlight how infrequent and rare these malignant cases are.

Pituitary adenomas usually affect individuals in their mid 30’s or low 40’s. That being said, they have been cases of these tumors affecting children as well. Pituitary adenomas can be either functioning adenomas, which means that they produce hormones or non-functioning adenomas meaning they don’t produce any hormones. In addition, they can be divided into two types of adenomas.

Macroadenomas: adenomas which measure at least 1cm in size. These adenomas can cause pressure on nearby cells or cranial nerve structures owing to their size.

Microadenomas:  adenomas which measure less than 1 cm in size. Majority of the pituitary adenomas are classified as microadenomas.

Symptoms

Symptoms usually vary depending on the size and type of the tumor. The presence of the following symptoms may indicate a pituitary tumor:

• Vision problems including blurred or double vision, enlarged pupil, eyelid drooping in case of a large tumor
• Splitting headaches around the forehead area caused by pituitary apoplexy
• Hypothyroidism (low thyroid hormone level) which can result in a loss of appetite and decreased mental function
• Impaired sense of smell
• Loss of sexual function
• Early menopause
• Depression
• Fatigue
• Osteoporosis
• Nausea or vomiting
• Adrenal insufficiency – known to cause low blood pressure and electrolyte abnormalities
• Hypogonadism or infertility
• Disruptions in menstrual periods or fertility issues in women
• Diabetes insipidus – a condition which causes frequent urination and excessive thirst
• Unexpected weight gain
• Acromegaly – which causes growth problems in adults and gigantism in children
• Unexplained weight loss
• Easy bruising of the skin accompanied by muscle weakness
• Aching joints
• Carpal tunnel syndrome
• Loss of body and facial hair
• Galactorrhea – which causes the spontaneous flow of breast-milk despite not being pregnant or nursing of an infant

Causes

In most cases, there’s no real reason for the pituitary adenoma to develop. Studies have revealed that genetic mutations, especially in the GSP gene, can result in unregulated growth of cells resulting in a pituitary tumor. A pituitary tumor can also be inherited. It has been reported that some genetic abnormalities known as Multiple Endocrine Neoplasia type 1 (MEN-1) have known to cause pituitary tumors. Accordingly, nearly 30 percent of patients with MEN-1 have reported having pituitary adenomas.

Similarly, patients afflicted with Carney complex are also said to be at a greater risk of developing pituitary adenoma. Another genetic condition – Familial isolated pituitary adenoma (FIPA) –said to be influenced by changes in the AIP gene have also been linked with adenomas.

Besides these genetic mutations, there’s no other cause responsible for causing pituitary tumors – including environmental factors. In addition, there’s no verified link of these tumors being associated with smoking, drinking or even viral infections. That being said, age does play a factor as the risk of contracting pituitary adenomas does increase with age. Further, they are more prevalent in women as compared to men.

Diagnosis and Treatment

On suspicion of a pituitary tumor, the concerned medical professional will perform a physical examination and order the patient’s complete medical history. He will also run several diagnostic tests including scans such as MRI, CT Scan, X-Rays etc. Urine and blood tests will also be analyzed to confirm the diagnosis.

In some cases, the blood tests will be used to confirm whether the tumors are indeed pituitary tumors as there’s a good likelihood of it being aneurysms, craniopharyngiomas, and meningiomas as well.

Treating a pituitary adenoma depends on several factors, including the type of pituitary tumor, the size of the tumor, the extent the tumor has spread, the patient’s age, and overall health. In most cases, surgical removal is suggested by expert neurosurgeons who specialize in minimally invasive endoscopic endonasal techniques. A trans-sphenoidal hypophysectomy which is performed through the nose might also be recommended in some cases. It needs to be mentioned that small tumors don’t mandate any treatment but they should be analyzed from time to time.

Some prolactin-producing tumors may be responsive to medical therapy in the forms of pills such as bromocriptine or cabergoline. It has been reported that in 90 percent of the individuals, there has been a significant reduction in the size of the tumor as well as prolactin levels thanks to medical therapy. However, care should be taken to ensure that medication is continued indefinitely, else the tumor will grow uninhibited.

In cases where the tumors cannot be removed surgically or where the patient is not responding to medications, radiation therapy may be necessary. Radiation therapy has proven to be an effective method for controlling the growth of these tumors. There are three types of radiation which are recommended:

• Standard External Beam Radiotherapy
• Proton Beam Treatment
• Stereotactic Radiosurgery