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Patient Guide

Pituitary Incidentaloma

  • Editors
  • Pamela Freda, MD, Columbia College of Physicians and Surgeons

    Laurence Katznelson, MD, Stanford University

    Mark Molitch, MD, Northwestern University Feinberg School  of Medicine

The pituitary is an important gland near the base of the brain that makes different types of hormones, which in turn control many functions of the body. A pituitary incidentaloma is a tumor or other lesion (an area of abnormal tissue) on or near the pituitary gland. It is found when a person has an imaging test for an unrelated reason. Doctors call this an “incidental” finding, meaning by chance—thus, the name incidentaloma.

This surprise finding is more common than you might think. In studies of adults who had head imaging with MRI (magnetic resonance imaging) or CT (computed tomography) scans for reasons other than pituitary disease, small incidentalomas were present in up to 20 percent of patients. People may find out they have this lesion when they get imaging after a neck or head injury, or because they have symptoms that are due to something else.

Suddenly finding out that you have a pituitary lesion may seem scary. The good news is that these lesions are almost always benign (not cancerous) and seldom need surgery. However, they sometimes can interfere with the normal function of the pituitary gland or cause a hormone imbalance.

This guide for patients is based on The Endocrine Society’s practice guidelines for physicians about the diagnosis and treatment of pituitary incidentaloma in adults.

What are the types of pituitary incidentalomas?

The most common type of incidentaloma is a benign pituitary tumor called an adenoma. Other incidentalomas are benign growths near the pituitary that are not tumors. They can interfere with the gland in much the same way as tumors. These growths include congenital (present at birth) cysts called Rathke’s cleft cysts and craniopharyngiomas. This guide applies the term lesion to both tumors and non-tumor growths.

Some pituitary tumors are secretory, meaning they make hormones. If the tumor makes too many hormones, it is hypersecreting. One common type of hypersecreting adenoma is a prolactinoma. This benign tumor makes too much prolactin, a hormone that stimulates breast milk production after childbirth and affects sex hormones.

Other pituitary tumors are non-secretory, meaning they do not make hormones. Based on blood testing, most incidentalomas show no evidence of hormone overproduction and most are probably non-secretory tumors.

Some incidentalomas cause the pituitary to make too few hormones, a condition called hypopituitarism. This happens if the lesion—whether a tumor or a non-tumor growth—presses on the normal pituitary gland.

If pituitary incidentalomas are smaller than 1 centimeter (cm), which is less than 4/10 of an inch, they go by the name micro-incidentalomas. Those larger than 1 cm are macro-incidentalomas. The larger lesions are less common but are more likely to press on the pituitary or nearby tissues.

What are the symptoms of pituitary incidentalomas?

Since these lesions are found by chance, most of them have not caused symptoms. Most incidentalomas grow slowly and will not grow to the extent that they cause problems. That is why doctors needed guidelines for testing and treatment of patients with these lesions.

When symptoms do occur from an incidentaloma, they depend on whether the cause is pressure of the lesion (mass effect) or hormone changes (too many or too few hormones).

Effects of lesion pressure include:

Symptoms related to low pituitary hormones include:

Symptoms of excess hormones vary widely, depending on the hormone affected. Just a few of the possible symptoms appear below.

Symptom Tumor causing the symptom Name of condition
Infertility, low sex drive, and/or bone loss; breast milk production when not pregnant Prolactinoma Hyperprolactinemia
Enlargement of hands, feet, and facial bones Growth hormone-producing tumors Acromegaly
Excess body fat around the midsection and upper back Tumors that produce too much adrenocorticotropic hormone (ACTH) Cushing’s disease

What tests are needed after diagnosis?

All patients with an incidentaloma, even if they have no symptoms, should have a complete physical exam with an endocrinologist or other physician. They also should have blood tests to check for abnormally high or low hormone levels.

If a CT scan found your lesion, you should get an MRI if possible. This test gives a better picture of the extent of the lesion.

You should have a visual field test if an MRI shows that your lesion is in a place where it could affect your vision. This includes a lesion next to the optic nerve (the nerve from each eye that carries images to the brain) or the optic chiasm (where the two optic nerves cross). A visual field test measures your full field of vision, including your peripheral (side) vision and central vision.

What follow-up care is recommended?

Most patients will not need surgical removal of the lesion. Few types of non-secretory incidentalomas shrink with medical treatment, so drug therapy is not routine for this type of lesion.

All patients still will need monitoring to make sure the lesion is not growing or causing health problems. Doctors sometimes call this careful observation a “watch and wait” approach. Your physician will tell you how often to return for visits and tests.

In general, experts recommend the following schedule:

When does a pituitary incidentaloma need surgery?

Doctors recommend surgery to remove the lesion if any of these problems is present:

Some doctors may suggest surgery as an option when a patient has:

Surgeons often can remove the lesion through your nose (transsphenoidal microsurgery). In most patients who have visual field problems, vision improves after surgery.

Surgery does not always relieve headaches or hypopituitarism. Ask your doctor whether the possible benefits of surgery outweigh the potential risks.