A sellar mass is an abnormal growth or tumor located within or around the sella turcica, a specialized anatomical structure at the base of the skull. The sella turcica, which translates from Latin to “Turkish saddle,” is a saddle-shaped depression in the sphenoid bone. This small, protected bony compartment houses the pituitary gland, an organ that controls the body’s entire hormonal system. The presence of a mass in this confined space can cause serious health issues due to pressure on surrounding structures or hormonal dysregulation.
Understanding the Sella Region
The sella turcica is a crucial central hub in the brain, situated directly behind the nasal sinuses. Bony walls form the boundaries of this fossa, while a membrane called the diaphragma sellae forms the roof, with a small opening for the pituitary stalk. This small area houses the pituitary gland, often called the “master gland,” which secretes hormones that regulate growth, metabolism, reproduction, and stress responses. The tight quarters of the sella region mean that even small masses can cause significant problems. Just above the pituitary gland, the optic chiasm sits in close proximity, where the optic nerves from both eyes cross over. Upward expansion of a sellar mass can compress the optic chiasm, directly interfering with vision. The lateral sides of the sella are bounded by the cavernous sinuses, which contain major blood vessels and nerves that control eye movement.
Types of Masses Found in the Sella
The vast majority of growths found in the sella region originate from the pituitary gland, with pituitary adenomas accounting for approximately 85% of all sellar masses. These adenomas are benign tumors classified by size: a microadenoma is less than 10 millimeters, and a macroadenoma is 10 millimeters or larger. Adenomas are also categorized as functional or non-functional, depending on their ability to secrete hormones.
Functional adenomas actively produce excess pituitary hormones, such as prolactin, growth hormone, or adrenocorticotropic hormone, leading to distinct clinical syndromes. Prolactinomas are the most common type of functional adenoma. Non-functional adenomas do not secrete hormones but cause symptoms purely through their physical size and pressure on surrounding structures. Other less common lesions can develop in the sella region. These include craniopharyngiomas, which are slow-growing tumors that often contain cystic and calcified components. Rathke cleft cysts are benign, fluid-filled sacs that develop from embryonic tissue and are often discovered incidentally. Meningiomas, which arise from the protective membranes surrounding the brain, also account for a small percentage of sellar masses.
Recognizing the Signs and Symptoms
Sellar masses produce symptoms in two main ways: through hormonal effects caused by pituitary dysfunction and through mass effect caused by physical pressure. Hormonal symptoms result from either hormone over-secretion or, conversely, compression of the normal gland causing hormone under-secretion, known as hypopituitarism. Over-secretion of prolactin can lead to galactorrhea (unexpected milk production) and menstrual irregularities in women, or hypogonadism and erectile dysfunction in men. Excess growth hormone results in gigantism in childhood or acromegaly in adults, characterized by the enlargement of the hands, feet, and facial features. When a mass compresses normal pituitary tissue, hormone deficiency can cause symptoms like fatigue, weight changes, cold intolerance, or loss of libido.
Mass effect often causes headaches. The most specific symptom of mass effect is vision loss, which occurs when the mass pushes upward on the optic chiasm. This compression typically results in bitemporal hemianopsia, a loss of peripheral vision in both outer visual fields.
Identifying and Treating Sellar Masses
The diagnostic process for a suspected sellar mass relies on both imaging studies and laboratory testing. Magnetic Resonance Imaging (MRI) of the sellar region is the preferred imaging method, as it provides detailed pictures of the soft tissues to characterize the size, location, and nature of the mass. Computed tomography (CT) scans may also be used, particularly to identify calcifications, which are characteristic of lesions like craniopharyngiomas. Hormone level testing is an important diagnostic step, involving blood and sometimes urine tests to measure pituitary hormones and the hormones they control. Testing for high prolactin levels or measuring insulin-like growth factor 1 (IGF-1) helps confirm a functional adenoma. Visual field testing is also performed to assess the extent of vision loss caused by optic chiasm compression.
Treatment strategies are individualized and depend on the mass type, size, function, and symptom severity. For small, non-functional masses causing no symptoms, watchful waiting with regular MRI scans and hormone checks may be appropriate. Functional adenomas, particularly prolactinomas, are often managed with medical therapy, using dopamine agonists to shrink the tumor and reduce hormone production.
Surgical intervention is the main treatment for masses causing significant mass effect, such as vision loss, or for tumors that do not respond to medical therapy. The most common surgical approach is transsphenoidal surgery, where the surgeon accesses the sella turcica through the nasal cavity and sphenoid sinus, avoiding the need to open the skull. Radiation therapy, including stereotactic radiosurgery, may be used as a secondary treatment option, often following surgery to treat residual tumor tissue.