Pituitary adenomas are the third most common intracranial tumor and arise from the pituitary gland.
Surgical removal is indicated for the great majority of symptomatic pituitary adenomas with the exception of prolactinomas. Transsphenoidal surgical removal (via the nose) is typically the treatment of choice. Fortunately, pituitary adenoma surgery has had major technical advances over the last two decades, including use of high-definition endoscopy, surgical navigation techniques and more effective skull base closure methods.
At Pacific Pituitary Disorders Center, we have one of the world’s largest experiences in endonasal endoscopic transsphenoidal surgery for all types of pituitary adenomas including acromegaly, Cushing’s disease, prolactinomas, non-functional adenomas, pituitary apoplexy and residual or recurrent adenomas. By incorporating leading edge technology and instrumentation with proven surgical experience of over 1600 endonasal surgeries, our pituitary tumor specialists make pituitary surgery safer, less invasive and more effective.
What is a Pituitary Adenoma?
Pituitary adenomas arise from the pituitary gland and are by far the most common growth associated with the gland; they account for 15% of primary brain tumors and are the third most common intracranial tumor after meningiomas and gliomas. The great majority (over 90%) of pituitary adenomas are benign slow growing tumors, approximately 5-10% are somewhat more aggressive (atypical) and less than 1% qualify as pituitary carcinoma. From autopsy studies and MRIs of normal individuals, it is known that 10-20% of the general population has a pituitary adenoma. Most of these tumors remain small and do not cause significant harm or symptoms; however many do progress and grow to cause hormonal and neurological problems.
Pituitary Adenomas are classified by size and whether they produce pituitary hormones; microadenomas are less than 1 cm in diameter and macroadenomas are over 1 cm in diameter. Adenomas that make excess hormones (endocrine-active adenomas) include prolactin-secreting adenomas known as prolactinomas, adrenocorticotropic hormone (ACTH) secreting adenomas causing Cushing’s disease, growth hormone (GH) secreting adenomas causing acromegaly, and thyroid stimulating hormone (TSH) secreting adenomas causing hyperthyroidism.
Adenomas that do not make excess hormones are called endocrine-inactive or Non-Functional Adenomas. Most adenomas are not genetically inherited; cases of familial pituitary tumors are rare. Multiple Endocrine Neoplasia (MEN) type I accounts for less than 5% of cases of pituitary adenomas. This autosomal dominant condition is characterized by multiple and sometimes simultaneous tumors of the pituitary, pancreas and parathyroid glands. Pituitary adenomas develop in 25% of patients with MEN I.
What are the Symptoms of a Pituitary Adenoma?
Pituitary adenomas may cause problems because of hormonal hypersecretion, pituitary hormonal failure, vision loss, headaches and/or bleeding into the tumor (apoplexy).
The three most common hormonally active adenomas are prolactinomas, GH-secreting tumors causing acromegaly, and ACTH-secreting tumors causing Cushing’s disease. Thyroid stimulating hormone (TSH) tumors are relatively rare.
(Hypopituitarism) This problem typically occurs only in larger tumors (macroadenomas) and results from compression and damage to the normal pituitary gland from the enlarging adenoma. Manifestations may include hypogonadism (sexual dysfunction, loss of libido, and impotence), hypothyroidism (fatigue, weakness, weight gain, coarse dry hair and dry skin, cold intolerance, depression), adrenal insufficiency (fatigue, weakness, loss of appetite, dizziness, nausea and vomiting), growth failure (in children and adolescents), hyperprolactinemia due to “stalk effect” (seen in diseases within or near the pituitary gland and stalk, interfering with the delivery of dopamine, a neuron-transmitter, from the hypothalamus to the prolactin secreting cells of the pituitary gland), which can result in hypogonadism and its associated problems. Rarely posterior pituitary gland damage occurs with diabetes insipidus, which is caused by the inability of the kidneys to conserve water leading to frequent urination and thirst. Learn More
Larger pituitary macroadenomas often cause loss of visual acuity or peripheral vision (termed bitemporal hemianopsia) from pressure on the optic nerves and optic chiasm which is directly above the pituitary gland. Larger macroadenomas especially those that have hemorrhaged (apoplexy) may also cause double vision.
Patients with macroadenomas often have frontal, forehead and temporal area headaches. Pituitary adenoma removal often results in headache resolution.
Bleeding (pituitary apoplexy)
This condition develops over hours to several days from hemorrhage and/or infarction of pituitary adenoma (typically a macroadenoma or a Rathke’s cleft cyst). Symptoms may include headache, nausea, visual loss, double vision and confusion. Most patients have undiagnosed hormone insufficiency prior to the apoplectic event. Pituitary Apoplexy is best confirmed by MRI. A head CT will also show areas of bleeding or a mass in the sella in the majority of cases. Other conditions that can mimic pituitary apoplexy are a ruptured aneurysm, meningitis, a stroke, intracerebral hemorrhage and migraine headache. The treatment for most patients with pituitary apoplexy is urgent endonasal endoscopic surgery and intravenous administration of the stress hormone cortisol.
How are Pituitary Adenomas diagnosed?
Pituitary adenomas are best diagnosed by imaging studies and hormonal testing.
The imaging study of choice is an MRI of the pituitary gland without and with gadolinium (a contrast agent). A brain MRI or CT scan will also reveal most pituitary macroadenomas but may not reveal smaller microadenomas. In a minority of patients it may be difficult to distinguish an adenoma of the pituitary from other masses which may include craniopharyngioma, Rathke’s Cleft cyst, meningioma, Hypophysitis (pituitary inflammation), glioma of the suprasellar region, metastatic tumor or chordoma.
Evaluation of pituitary gland function either for under-production (hypopituitarism, or pituitary failure) or over-production of hormones should include blood levels of ACTH, cortisol, TSH, free T4 (thyroid function), LH (luteinizing hormone), FSH (follicle-stimulating hormone), estradiol in women, testosterone in men, GH (growth hormone), IGF-1 (insulin-like growth factor, growth hormone’s target hormone, also known as somatomedin-C), and prolactin. Given that some tests need to be performed at a certain time of the day, and stimulation tests may be needed to diagnose some endocrine-active tumors (Cushing’s disease or acromegaly), this testing should be overseen by an endocrinologist.
Patients with visual complaints or those whose tumors that contact the optic nerves or optic chiasm should receive a full ophthalmological evaluation. This evaluation should include acuity (vision quality) testing of each eye and formal visual field testing to determine if there is loss of peripheral vision.
How are pituitary adenomas treated?
Endonasal Endoscopic Surgery
The first-line treatment for all pituitary adenomas except prolactinomas (as discussed below), as well as RCCs and most craniopharyngiomas is endonasal endoscopic transsphenoidal surgery. Because of improved tumor visualization and tumor removal rates, the endonasal endoscopic approach has become the preferred method for removal of pituitary adenomas, RCCs, as well as the great majority of craniopharyngiomas, clival chordomas and many midline meningiomas.
Surgical success rates (complete tumor removal and normalization of hormonal hypersecretion) are generally quite high (>80-90%) with smaller and non-invasive pituitary adenomas, but are lower for large or invasive macroadenomas (40-70%). Major surgical complications such as vision loss, bleeding, stroke, cerebrospinal fluid leak and meningitis are low when performed by experienced endonasal transsphenoidal neurosurgeons who often work collaboratively with a Head & Neck surgeon. The success rates of surgery are described further in the sections below for specific tumor types.
Endonasal Endoscopic Surgery
Animation | Play Video
A craniotomy (opening in the skull from above to reach the pituitary region) is required in less than 1% of patients who require surgery for a pituitary adenoma.
Medical & Radiation Therapies
Hormone Replacement Therapy
Many patients with pituitary adenomas will develop varying degrees of hypopituitarism (pituitary gland failure) either as a result of the tumor impact on the gland or sometimes as a result of surgery or other treatments. While many patients can have some degree of gland recovery, many will ultimately require short-term or long-term hormone replacement therapy. Our highly experienced pituitary endocrinologists, Drs. Pejman Cohan and Niloufar Ilani can provide tailored hormone replacement therapy including for low testosterone, low estrogen, growth hormone deficiency, hypothyroidism, low cortisol (adrenal insufficiency) and diabetes insipidus (anti-diuretic hormone deficiency).
For prolactinomas that are typically treated with medical therapy, we have highly experienced endocrinologists to provide this therapy. For patients with adenomas that cannot be completely treated with surgery and/or medical therapy, our outstanding radiation oncologists can deliver focused radiosurgery or radiotherapy to tumors, halting their growth. We also have clinical trials available using novel medical therapies for patients with persistent acromegaly and Cushing’s disease who failed prior treatments.
Learn more about Pituitary Adenomas:
- Cushing’s disease
- Endocrine-Inactive Adenoma
- Pituitary Apoplexy
- Recurrent and Residual Adenoma
- Learn more about our multidisciplinary team
- See our pituitary adenoma publications