Pituitary adenoma

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 28, 2016
StartDiseasesPituitary adenoma

A pituitary adenoma or PA is a tumor that occurs in the pituitary gland, and they are most often benign. Sometimes when the pituitary gland becomes covered with adenomas, it begins to secrete an excess of hormones, which can have wide-ranging effects on the body.

Contents

Definition & Facts

The pituitary gland is located below the brain and above the nasal passages. This gland belongs to the endocrine system, which includes the pancreatic gland, adrenal gland, thyroid gland, and a number of other glands and organs. The pituitary gland is the central part of the endocrine system that activates other glands throughout the body.

Pituitary adenomas are rarely diagnosed. As of 2014, there were 10,000 cases of pituitary adenoma diagnosed per year; however, as many as 1 in 4 people may have these adenomas without any signs or symptoms. There are multiple types of PA, and they are:

  • Microadenoma
  • Macroadenoma
  • Functional
  • Nonfunctional

Microadenoma and macroadenoma both refer to the size of the tumor – less than and greater than one centimeter in size respectively. Functional and nonfunctional adenomas refer to the status of hormone secretion – whether it is active or not. 

Symptoms & Complaints

Sometimes as the gland begins to become overridden with tumors, it activates different glands throughout the body, which in turn causes hormones to become secreted. A few hormones that become secreted due to a PA are:

The growth hormone causes a person to grow excessively, which is known as gigantism or acromegaly. Growth occurs throughout the body including the feet, hands, tongue, forehead, and jaw. This can radically alter a person's appearance.

Prolactin causes the mammary glands in both males and females to become overactive, causing them to produce milk; these symptoms are known as hyperprolactinemia. Though the cases of male lactose production are rare, they are still possible; however, in males the more common symptom is lowered sex drive

When the thyroid glands begin to over-secrete hormones, this causes hyperthyroidism. The most prevalent symptoms include hyperactivity, eye-bulging, and nervousness. If there are any pains within the chest or problems with breathing, then medical attention should be sought immediately as these could be life threatening.

Cushing’s syndrome is when the adrenal glands produce an overabundance of corticosteroid or adrenocorticotropic hormones. Symptoms include problems related to blood (e.g., high blood pressure, hyperglycemia, and easy bruising), mood changes, roundness of the face, and possible weakening of the bones.

Both luteinizing hormone and follicle-stimulating hormone are referred to as gonadotropin. Gonadotropin is produced to regulate sperm creation in men and egg production in women. When over or under-stimulation of the gonads occur, the levels of testosterone or progesterone change significantly, leading to rare cases of reproductive disorders. Lowered sex drive (for both males and females) and menstrual cycle changes in females are symptoms of the disorder.

Causes

Causes of pituitary adenomas are unclear; however, a rare genetic disorder known as MEN 1 or multiple endocrine neoplasm 1 disorder is connected with PA. MEN 1 is statistically found in 1 out of 30,000 people. This disorder primarily affects three glands, causing overgrowth and hyperactivity in:

The creations of tumors throughout the body are controlled by a substance called menin. When menin levels are modified throughout the body, then the production of tumors is increased. There are small percentages (1 out of 10 people) who obtain MEN 1 while having no family history of the disorder.

Diagnosis & Tests

Diagnosis is typically accidental. A doctor or physician may discover a PA by symptoms and diagnosis of other ailments or health problems. Since the placement of the pituitary gland is so close to the nerves necessary for vision, the initial tests may be done to verify one’s vision. Other questions about one’s medical history of tumors may be asked as well to determine the likelihood of MEN 1. Urine testing and blood tests are also used to determine the presence of the hormone.

Blood tests are completed to check for hormone imbalances. In blood tests where corticotropin levels are elevated, MRI scans may be performed to ensure normal brain tissues and sizes. MRIs scan the cranial area for any deformities in the pituitary gland and check for tumors down to the size of three millimeters.

If the MRIs return a normal cranial scan, then a procedure known as inferior petrosal sinus sampling is performed. In this procedure, two tubes are inserted into two veins on the inner thighs. An injection is then administered to activate the production of corticotropin. If there is a large fluctuation in corticotropic hormones between both sides, then the diagnosis may be pituitary adenoma.

In certain cases where hormone levels are insufficient for proper diagnosis, a biopsy of the pituitary gland is ordered. This is where a sample of the gland is extracted and examined under a microscope.

Treatment & Therapy

Removal of a pituitary adenoma is possible, while post-operational medication is sometimes necessary. However, in some nonfunctional cases, where the gland is not secreting excess hormone, surgery may not be performed until the tumor becomes problematic.

The surgery that will typically be performed to remove pituitary tumors is an endoscopic transsphenoidal surgery (ETS). In an ETS, the neurosurgeon is assisted by an ear, nose and throat (ENT) surgeon. The surgeons will enter through the nasal cavity (in a minimally invasive surgery), and then cut a slit into the sphenoid sinus area. Holes are then made in bony areas in order to allow access to the tumor. An endoscope or microscope is then used to monitor the removal of the tumor.

Surgeries for smaller tumors commonly have higher success rates than those for larger tumors. In traditional methods, a slit is cut below the lip and a chunk of the sinus cavity is removed to allow the surgeon direct access to the tumor. Similar to the minimally invasive surgery, holes are made in bony areas to allow access to the tumor. An endoscope or microscope is used to monitor the surgery and removal of the tumor as well. Some procedures have complications post-op; these include:

In other cases, where the patient is deemed unfit for surgery, radiation-based therapy is administered to the patient to break up the tumor. Brain stereotactic radiosurgery is sometimes performed to aim directly at the tumor to destroy it.

Prevention & Prophylaxis

Since the disease is commonly diagnosed in patients who have a clinical history of tumors, it is important for patients to regularly be screened and monitored for any growth.