What is a Macroadenoma?
A macroadenoma is a benign tumor composed of glandular tissue growth larger than 10 mm (those under 10 mm are called microadenomas). They usually form in the adrenal and pituitary glands, but they can also form in the colon, kidneys, and thyroid gland.
Pituitary macroadenomas can cause Cushing’s syndrome, acromegaly, hyperthyroidism, and, rarely, symptoms related to decreased secretion from the pituitary gland. Symptoms of a pituitary macroadenoma can include the following:
- Problems with eyesight
- Unexplained hair growth or loss
- Weight changes
- Menstrual or breast changes
- Erectile dysfunction
Surgery is the best form of Macroadenoma treatment and the only way to achieve a cure. Your surgeon will gain access to your pituitary gland using the transsphenoidal approach—so named because the route crosses, or transects, your sphenoid bone. This bone is located behind your nose mostly within your skull.
Using precise surgical instruments, your surgeon will make an incision through your nasal cavity to create an opening in your sphenoid bone. Once your surgeon gains access to your sphenoid sinus (the air-filled area behind the sphenoid bone), further incisions will be made until a hole is created in the sella turcica—the bone that cradles and protects your pituitary gland.
After your tumor appears in the operative field, removal of the tumor can proceed. Your surgeon will use high magnification to readily distinguish normal pituitary tissue from the macroadenoma.
Once the tumor has been removed, your surgeon will clean the tumor cavity and seal it.
At Barrow Neurological Institute at Dignity Health St. Joseph’s Hospital and Medical Center, our surgeons specialize in two types of surgery for macroadenomas:
- Microsurgery uses a powerful operating microscope to help your surgeon distinguish between tiny structures in and around your pituitary gland
- Endoscopic surgery uses small tubes and a tiny camera to help your surgeon remove your tumor in small pieces
Both surgeries aim to minimize trauma to the tissue surrounding your pituitary gland while facilitating a speedy recovery with as little pain or discomfort as possible. Each technique has its own inherent advantages and disadvantages, and your surgeons will work with you to help determine which is the best fit for you.
Most patients are able to return home the day after their surgery for removing a pituitary macroadenoma, and nasal packing is seldom required.
Gamma Knife radiosurgery is a highly advanced form of radiotherapy that is used to achieve similar results to the traditional surgical techniques described above. However, with Gamma Knife it can take several years for abnormal hormone levels caused by your macroadenoma to return to normal, rather than days or weeks as with traditional surgery.
The ‘knife’ in this surgery is actually made up of many small beams of radiation focused on a single point. Each individual beam is too weak to damage healthy tissue, but at the point where the beams converge they deliver a dose of radiation that is lethal to the tumor.
Gamma Knife is an outpatient procedure, does not involve any incisions, and requires only brief sedation under general anesthetic.
If your pituitary macroadenoma is affecting hormone levels in your body, your doctor may prescribe medication to replace the hormones with synthetic hormones or to block the action of the macroadenoma on pituitary hormone production.
How common are pituitary macroadenomas?
A family history of multiple endocrine neoplasia type 1 (a hereditary condition) can increase your chances of developing a pituitary macroadenoma or other types of macroadenomas of the endocrine system.
How are pituitary macroadenomas diagnosed?
Your doctor may suspect you have a macroadenoma if you have the symptoms listed above. Possible tests to confirm this diagnosis include the following:
- Blood tests
- Urine tests
- Visual field tests
- Computed tomography (CT)
- Magnetic resonance imaging (MRI)
- Inferior petrosal sinus sampling (IPSS)
Is a pituitary macroadenoma curable?
A macroadenoma can be cured in some cases with surgery. When a pituitary tumor is large and has grown into nearby structures, it becomes more difficult to remove.
Is a macroadenoma cancerous?
A macroadenoma is almost always noncancerous, meaning it does not spread to other parts of the body.
What causes a pituitary macroadenoma?
It is not known exactly what causes a pituitary macroadenoma. Some people inherit gene mutations that increase their risk of developing these tumors. Other cases are sporadic, meaning there is no family history. Gene mutations may still be involved in sporadic cases.