A sellar mass refers to any growth or abnormality located in a specific area at the base of the brain. This region, known as the sellar region, is situated near the pituitary gland, a small but powerful organ that controls many bodily functions. Because of its proximity to this gland and other important structures, a sellar mass can potentially affect various systems throughout the body.
Understanding Sellar Masses
A sellar mass is an abnormal growth within the sella turcica, a saddle-shaped indentation in the sphenoid bone at the base of the skull. This bony cavity protects the pituitary gland. Though small, the sella turcica houses critical nervous, vascular, and endocrine components.
Its location is significant due to its close proximity to several structures. Above the pituitary gland are the optic nerves and optic chiasm, vital for vision. On either side, the cavernous sinuses contain nerves controlling eye movement and sensation, along with major blood vessels like the carotid arteries.
A mass in the sellar region can exert pressure on these nearby structures. This compression can disrupt pituitary gland function, leading to hormonal imbalances. Pressure on the optic nerves can cause visual disturbances, while effects on surrounding nerves and blood vessels can lead to other neurological symptoms.
Common Types of Sellar Masses
The most frequently encountered sellar mass is the pituitary adenoma, a benign (non-cancerous) tumor arising from pituitary gland cells. These adenomas are categorized by size: microadenomas are less than 10 millimeters, while macroadenomas are 10 millimeters or larger and may extend beyond the sella. Some pituitary adenomas produce excess hormones, leading to specific imbalances, while others do not secrete hormones.
Other types of sellar masses include craniopharyngiomas, which are benign tumors developing from embryonic tissue remnants. These often contain solid and cystic components and may have calcifications. Rathke’s cleft cysts are non-cancerous, fluid-filled sacs also formed from embryonic tissue remnants within the sella.
Meningiomas originate from the meninges, the protective membranes surrounding the brain and spinal cord. These slow-growing tumors can occur in various locations, including the sellar region. Less commonly, vascular issues such as aneurysms, which are balloon-like bulges in blood vessels, can also manifest as sellar masses.
Recognizing the Symptoms
Symptoms of a sellar mass vary widely, depending on its size, type, and affected adjacent structures. Many symptoms arise from hormonal imbalances due to pituitary gland dysfunction. For instance, overproduction of growth hormone can lead to gigantism in children or acromegaly in adults, causing enlarged hands, feet, and facial features.
Conversely, a mass can impair the pituitary’s ability to produce sufficient hormones, resulting in hypopituitarism. This can manifest as fatigue, weight changes, low blood pressure, or reproductive issues due to decreased thyroid, adrenal, or sex hormone levels. Women might experience irregular menstrual cycles, while men could have reduced libido or erectile dysfunction.
Visual disturbances are common, particularly when the mass compresses the optic nerves or optic chiasm. This compression can lead to gradual vision loss, often affecting the outer (temporal) visual fields in both eyes, known as bitemporal hemianopsia. Other visual problems include blurred vision, double vision, or decreased color perception. Neurological symptoms like persistent headaches, facial pain, or numbness can also occur due to pressure on surrounding nerves.
How Sellar Masses Are Diagnosed
Diagnosing a sellar mass involves medical imaging and blood tests. Magnetic Resonance Imaging (MRI) of the brain is the preferred imaging method, providing detailed anatomical views of soft tissues in the sellar region. MRI can precisely visualize the mass, its size, and its relationship to the pituitary gland, optic nerves, and surrounding blood vessels. It helps determine if the mass is solid or cystic, and if it shows signs of hemorrhage or calcification.
Computed Tomography (CT) scans may also be used, particularly to assess bony structures of the sella turcica and sphenoid sinus, or to identify calcifications within the mass. While MRI excels at soft tissue detail, CT offers superior visualization of bone changes and aids in surgical planning.
Blood tests evaluate the functional impact of a sellar mass on the pituitary gland. These tests measure levels of various hormones produced or regulated by the pituitary, such as thyroid hormones, cortisol, growth hormone, prolactin, and sex hormones. Abnormal hormone levels indicate whether the mass is overproducing certain hormones or causing a deficiency in others.
Treatment Approaches
Treatment for a sellar mass depends on several factors, including the type and size of the mass, symptom presence, and the patient’s overall health. For many symptomatic sellar masses, surgical removal is a common approach. Transsphenoidal surgery is a minimally invasive procedure where the surgeon accesses the mass through the nasal cavity and sphenoid sinus, avoiding an open cranial incision. This method allows direct access to the sella turcica with minimal disruption to brain tissue.
Radiation therapy may be used, either as a primary treatment for certain types of masses or after surgery to target any remaining tumor cells. Stereotactic radiosurgery, a highly focused form of radiation, delivers precise doses to the mass while minimizing exposure to surrounding healthy brain tissue. This technique helps control tumor growth or shrink the mass over time.
Medication is another treatment option, particularly for hormone-producing pituitary adenomas. Specific drugs can reduce the production of certain hormones or even shrink prolactin-secreting tumors. These medications help manage symptoms related to hormonal imbalances and, in some cases, may eliminate the need for surgery. For small, asymptomatic sellar masses that are not growing or causing problems, a “watchful waiting” approach may be adopted, involving regular monitoring with imaging and hormone tests to track changes.