A pituitary adenoma often raises questions about its classification as a brain tumor. This article clarifies what a pituitary adenoma is, how it influences bodily functions, its identification, and management approaches. Understanding these aspects is important for individuals seeking information about this specific type of growth.
Understanding Pituitary Adenomas
The pituitary gland is a small, pea-sized endocrine gland located at the base of the brain, nestled within a bony structure called the sella turcica. This gland acts as a central regulator, producing and releasing hormones that control various bodily functions, including growth, metabolism, blood pressure, and reproduction. It also directs other endocrine glands to produce their hormones.
A pituitary adenoma is an abnormal growth or tumor that develops from the cells of the pituitary gland. While it resides within the cranial cavity, making its location similar to other brain tumors, it is distinct because it originates from the glandular tissue of the pituitary, not from the brain’s neural or glial cells. Most pituitary adenomas are benign, meaning they are non-cancerous and typically grow slowly, not spreading to other parts of the body like malignant tumors. These growths are classified by size: microadenomas are less than 1 centimeter, while macroadenomas are larger than 1 centimeter.
How Pituitary Adenomas Affect the Body
Pituitary adenomas can impact the body in two primary ways: through hormonal imbalances or by placing pressure on nearby structures. Some adenomas are “functioning” or “secreting,” meaning they produce excessive amounts of a specific hormone. For example, a prolactinoma, the most common type, leads to high prolactin levels, causing infertility, irregular menstrual periods in women, decreased libido, and milky breast discharge. A somatotroph adenoma secretes excess growth hormone, potentially leading to acromegaly in adults, characterized by enlarged hands, feet, and facial features. Corticotroph adenomas produce too much adrenocorticotropic hormone (ACTH), resulting in Cushing’s syndrome, with symptoms such as weight gain, a rounded face, muscle weakness, and high blood pressure.
Other adenomas, termed “non-functioning,” do not produce excess hormones but can still cause problems due to their size. As these tumors grow, they can compress the normal pituitary gland, leading to a deficiency in essential hormones, a condition known as hypopituitarism. This can manifest as fatigue, weakness, low blood pressure, and changes in menstrual cycles or erectile dysfunction. Additionally, a larger adenoma can exert pressure on surrounding brain structures. Given the pituitary gland’s proximity to the optic nerves and optic chiasm, tumor growth can lead to vision problems, most notably a loss of peripheral vision, as well as blurred or double vision, and headaches.
Identifying a Pituitary Adenoma
A pituitary adenoma is often suspected based on a person’s symptoms, which can vary widely depending on the tumor’s size and whether it is producing hormones. Common indicators that may prompt medical evaluation include persistent headaches, unexplained changes in vision, alterations in weight, menstrual irregularities, or unusual fatigue.
Once a pituitary adenoma is suspected, medical professionals employ specific diagnostic tools. Blood tests are frequently performed to measure hormone levels, which can reveal an excess or deficiency of specific pituitary hormones. Imaging techniques, particularly Magnetic Resonance Imaging (MRI) of the brain and pituitary gland, are essential for visualizing the tumor, determining its size, and assessing its proximity to surrounding structures. An eye exam, including visual field testing, may also be conducted to evaluate any impact on vision caused by the tumor’s pressure on the optic nerves.
Managing Pituitary Adenomas
Managing a pituitary adenoma is tailored to the specific type of tumor, its size, the symptoms it causes, and the individual’s overall health. For some hormone-producing adenomas, particularly prolactinomas, medication is often the initial treatment. These medications can shrink the tumor and normalize hormone levels.
Surgical removal of the tumor is a common intervention, especially for larger adenomas causing mass effects or when medication is not effective. The transsphenoidal approach, which involves accessing the tumor through the nose and sphenoid sinus, is a frequently used and minimally invasive surgical technique. In cases where surgery is not fully effective or feasible, or for residual tumor, radiation therapy may be considered. This treatment uses targeted radiation beams to control tumor growth.