Pituitary Adenoma - Types, Causes, Symptoms, Diagnosis, and Treatment

Introduction

The pituitary gland is a small pea-sized gland located in the skull base. It is also called the "master gland," as it controls the functions of different body parts by secreting many hormones. The hypothalamus and the pituitary gland work together to release various hormones that act in other body parts.

What Is Pituitary Gland?

The pituitary gland is a small pea-sized gland located in the skull base. It is also called the "master gland," as it controls the functions of different body parts by secreting many hormones. The hypothalamus and the pituitary gland work together to release various hormones that act in other body parts. The anterior (front) lobe and the posterior (back) lobe are its two lobes. Different hormones are released by each lobe. Hormones are chemicals that communicate with the organs, muscles, and other tissues through the bloodstream to regulate various bodily functions.

What Is Pituitary Adenoma?

Pituitary adenoma refers to noncancerous (harmless) growth in the front part of the pituitary gland. It does not spread to different body parts but can increase in size and put pressure on the surrounding structures. The nerves that supply the eyes, close to the gland, present symptoms due to pituitary adenomas, known as the "mass effect." Large adenomas can destroy the pituitary cells, leading to a decrease in the hormones produced by the pituitary. As a result, the patient may experience symptoms like fatigue, low blood pressure, and loss of interest in sexual activity. Pituitary adenomas are the most common tumors of the brain, and they do not cause any problems until they present symptoms.

What Are the Types of Pituitary Adenomas?

Pituitary adenomas are classified based on size, aggressiveness, and secretion of hormones.

Based on Size:

Pituitary adenomas are classified into two types based on their size.

• Microadenomas that are less than 1 cm in size.
• Macroadenomas that are more than 1 cm in size.

Based on Aggressiveness:

The nature and aggressiveness of the growth of adenomas classify them as the following:

• The benign (harmless) type is the most common and shows slow growth.
• Atypical pituitary adenomas that grow very rapidly but are rare.
• Pituitary carcinomas (malignant type) that spread to other body parts. Carcinomas of the pituitary are extremely rare.

Based on the Hormone Secretion:

The secretion of hormones by the tumors classifies adenomas into two types:

• Pituitary adenomas that secrete excessive amounts of hormones are called functional adenomas. The primary hormones that are secreted include:

  • Prolactin causes prolactinoma.

  • Growth hormone that causes acromegaly in adults and gigantism in children.

  • Cortisol causes Cushing's disease.

• Pituitary adenomas that do not secrete any active hormones are called clinically non-functional adenomas.

Who Is Affected by Pituitary Adenomas?

Although they can arise at any age, pituitary adenomas are more prevalent in those who are in their 30s or 40s. Pituitary adenomas are more common in women than in males and those identified as male at birth (AMAB).

What Is the Prevalence of Pituitary Adenomas?

Of all the tumors that grow inside the skull, between 10 % and 15 % are pituitary adenomas. Pituitary adenomas affect about 77 persons out of 100,000, although studies believe that as much as 20 percent of people may develop adenomas at some time in their lives. Pituitary adenomas, particularly microadenomas, are typically never discovered because many of the patients have no symptoms.

What Are the Causes of Pituitary Adenomas?

The exact cause of pituitary adenomas is unknown. However, a mutation (change) in the cell’s genetic material (DNA) can trigger an adenoma leading to an excessive division of the cells. In addition, parents may pass down the mutated gene to the children leading to inherited pituitary adenomas.

What Are the Symptoms of Pituitary Adenomas?

The symptoms of pituitary adenomas depend upon several factors like the hormones that are released, mass effects on the surrounding structures, and deficiency of the pituitary hormones.

Symptoms Due to Excessive Hormonal Secretion Are:

1. Growth Hormone-Secreting Adenomas: Excess growth hormone secretion causes acromegaly (adults) and gigantism (children). Hands and feet show enlargement, and body size increases significantly.

2. Prolactinoma: Excess production of the hormone prolactin causes prolactinoma which presents as breast milk production, irregular menstrual cycle in females, and loss of libido in males.

3. ACTH (Adrenocorticotropic Hormone)Secreting Pituitary Adenomas: That causes Cushing's disease. The symptoms include easy bruises, sudden weight gain, and muscle weakness.

4. TSH(Thyroid Stimulating Hormone)Secreting Pituitary Adenomas: These are very rare and lead to hyperthyroidism. The symptoms present unexpected weight loss, fatigue, nervousness, and rapid heartbeat.

The general symptoms noted include:

• Problems in vision.

• Nausea and vomiting.

• Nasal drainage.

• Headaches.

• Loss of sexual desire.

• Difficulty in conceiving.

• Irregular menstrual cycle.

• Early menopause.

• Tiredness.

• Sudden weight loss or gain.

• Muscle and joint aches.

• Behavioral changes.

Pituitary apoplexy is when the adenomas stop receiving blood supply due to an excessive increase in size that can lead to the death of tissues of the pituitary and present as severe symptoms like severe headache and sudden loss of vision. The symptoms arising due to a decrease in the hormonal levels can show up in a few days to weeks.

Can a Pituitary Adenoma Be Classified as a Brain Tumor?

Physicians consider pituitary adenomas brain tumors, despite the fact that the pituitary gland is an endocrine structure that is truly linked to the brain and not a part of it. Approximately 10% of initial brain tumors are comprised of them.

How Are Pituitary Adenomas Diagnosed?

The doctor diagnoses the condition based on the medical history and the signs and symptoms shown by the patient. Then, blood tests and scans are done to confirm the diagnosis.

1. Blood Tests: Blood tests help to detect and confirm pituitary adenomas by assessing the hormonal levels in the body. An increase in hormone levels indicates functional adenomas, and a decrease indicates pituitary insufficiency. Therefore, comprehensive hormone testing is essential to determine the excess or deficit of particular hormones like prolactin.

2. Imaging Tests: Magnetic resonance imaging (MRI) scans help detect adenomas greater than 4 millimeter in size. The 3T Tesla MRI scanner is used to detect tumors smaller than 4 mm. In addition, computed tomography (CT) is combined with MRI scans to get a better picture of the condition.

3. Visual Field Test: The doctor suggests this test when the patient complains of vision problems that occur due to pressure on the nerves supplying the eyes.

How Are Pituitary Adenomas Treated?

The treatment options for pituitary adenomas include surgery, medications, radiation therapy, or all three.

1. Surgery: Endoscopic surgery is performed using a camera and small tools that reach the pituitary through the nose and sinuses. The approach is referred to as the transsphenoidal technique. It is a minimally invasive technique. Alternatively, extensive surgery is indicated in cases where endoscopic surgery is not possible.

2. Medications: Medicines are used to treat certain tumor types that shrink the tumor and relieve the symptoms.

3. Radiation Therapy: High-energy X-rays that target the tumor cells and lead to a shrink in size of the tumors is used as radiation therapy. A particular type called stereotactic radiosurgery uses X-rays targeted on the adenomas from various directions.

Doctors recommend yearly check-ups to keep track of the condition after treatment. Blood tests and scans are conducted regularly, and a watch is held on the symptoms to monitor an increase in the size of adenomas.

Conclusion

The outlook of the condition depends on the type and size of the adenoma. Patients can return to their everyday lives post-treatment; however, there may be chances of recurrence. Treatment of adenomas that cause a decrease in hormonal levels needs hormone supplements. Periodic monitoring helps to appropriately assess the condition and the need for further treatment.