Pituitary macroadenomas are typically benign tumors that grow in the pituitary gland. Most are noncancerous, but they can still lead to health issues and will likely need treatment.

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Doctors classify pituitary adenomas by their size or origin cells. Macroadenomas are 10–40 millimeters (mm) in size and can cause symptoms.

This article reviews what pituitary macroadenomas are, their possible symptoms, causes, diagnosis, treatment, and frequently asked questions.

The pituitary gland is a small gland located at the base of the brain behind the bridge of the nose. It produces a variety of hormones that help regulate several aspects of the body, including:

In some cases, a person may develop a tumor on their pituitary gland, known as a pituitary adenoma. These tumors are generally benign (noncancerous), meaning they will not spread to other body areas.

Types

Doctors and researchers classify tumors based on their size or the cells they start in. Some types include:

  • Microadenoma: The tumor is less than 10 mm.
  • Macroadenoma: The tumor is 10–40 mm.
  • Giant adenoma: The tumor is greater than 40 mm.

Effects

Although the tumors are generally not cancerous, they can:

  • make excess hormones
  • press on parts of the brain and nerves
  • spread to surrounding areas, such as the skull or sinuses

In some cases, a macroadenoma may not produce any hormones. This is known as a non-functioning adenoma.

Pituitary macroadenomas can cause symptoms by putting pressure on surrounding areas. They can also secrete excess hormones.Pituitary macroadenomas that secrete hormones are known as functioning adenomas.

Symptoms associated with pressure from a macroadenoma include:

  • headache
  • vision issues, which occur in 40–60% of people with pituitary adenomas
  • hormonal deficiencies

Hormonal deficiencies may lead to various symptoms based on the affected areas of the body. Symptoms may include:

Symptoms as a result of additional hormones

If the pituitary macroadenoma is functioning, it releases additional hormones into the body. This can result in a variety of symptoms, including:

Many of the symptoms are nonspecific. This means that if a person does have one or more symptoms, it does not necessarily mean that they have a pituitary macroadenoma. However, if a person does experience one or more symptoms, they may still want to speak with a doctor.

In some cases, a person may not experience any symptoms. Instead, they may discover a pituitary adenoma when getting another examination.

The exact cause of pituitary tumors is unknown. The majority appear sporadically, with no previous medical or family history of the condition.

Genetic mutations are rarely a characteristic of pituitary macroadenomas. However, some mutated genes may play a role in the development of tumors, such as:

  • multiple endocrine neoplasia type 1
  • carney complex
  • multiple endocrine neoplasia type 4
  • familial isolated pituitary adenomas

When symptoms do not present, a doctor may discover a pituitary adenoma by accident during a CT scan.

Upon discovery, a doctor will likely order an MRI scan with a gadolinium contrast to help rule out an aneurysm and to determine if there is a hemorrhage.

A doctor may also order tests to check for hypopituitarism (a lack of pituitary hormones) and hypersecretion (too many pituitary hormones).

The Endocrine Society recommends a complete biochemical assessment to check the levels of the following hormones:

By understanding how pituitary macroadenoma is affecting a person’s hormone levels and body, a doctor can help tailor their treatment.

Doctors generally individualize treatments to meet a person’s needs.

In many cases, a person will need to work with an endocrinologist and a neurosurgeon to determine the best course of treatment. Often, it involves medications to correct hormone imbalances, radiation, or surgery to remove the adenoma.

Nonfunctioning macroadenoma

A doctor may recommend transsphenoidal tumor resection (surgery to remove the adenoma) for a nonfunctioning macroadenoma in the following situations:

  • bleeding of the tumor (pituitary apoplexy) with visual disturbance
  • other visual abnormalities, such as weakness of the eye muscles (ophthalmoplegia)
  • significant growth of the pituitary tumor over time
  • compression of the optic nerves or chiasm on imaging
  • visual field deficit due to tumor
  • loss of endocrine function

Functioning macroadenomas

With a functioning macroadenoma, a doctor may recommend monitoring a person’s prolactin levels if the person is asymptomatic.

A doctor may recommend the use of dopamine agonists to correct prolactin levels. These medications are about 90% effective in decreasing tumor size and correcting prolactin levels.

Doctors may recommend other medications in cases where the adenoma is secreting other hormones. A doctor will recommend medication based on the hormones and deficiencies found.

Other treatments may include radiation and removal of the functioning tumor. Typically, a doctor will only recommend surgery when a person does not respond well to other treatments.

Below are some frequently asked questions.

How serious is pituitary macroadenoma?

Pituitary macroadenomas may go unnoticed if they are asymptomatic. A doctor may only discover the tumor during a scan for another issue.

The outlook depends on whether the tumor is functioning or nonfunctioning. Nonfunctioning adenomas have a good outlook when treated early. Functioning versions may have a worse outlook, a higher level of comorbidities, and a lower life expectancy.

It is important that a person speak with a doctor to fully understand their type of tumor, their outlook, any comorbid conditions, and treatment next steps.

Are pituitary macroadenomas cancerous?

Typically, pituitary macroadenomas are not cancerous. They affect an unknown number of people — in part because they do not always cause symptoms or complications.

People may have genetic mutations that put them at higher risk of developing pituitary macroadenomas, but experts do not fully understand the underlying causes.

Is a pituitary macroadenoma curable?

Surgery and medical interventions can typically lead to a good outlook for people with a nonfunctioning pituitary macroadenoma. People with functioning adenomas may have a worse outlook. However, it is important that a person speak with their doctor to understand their unique case.

Pituitary macroadenomas are mostly benign tumors that grow on the pituitary gland. They are considered relatively common.

In some cases, they will not cause any symptoms. When they do, the symptoms may result from the tumor putting pressure on the surrounding areas or secreting or blocking hormones.

Treatments can include medications, radiation, or surgical removal of the tumor.