A sellar mass is any abnormal growth found in or near the sella turcica, a small bony cradle at the base of your skull that houses the pituitary gland. The vast majority of sellar masses are pituitary adenomas, which are benign tumors. They are remarkably common: autopsy and imaging studies estimate that about 16.7% of the general population has a pituitary adenoma, though most never cause symptoms or require treatment.
Where the Sella Turcica Sits
The sella turcica is a concave indentation in the sphenoid bone, located near the center of the skull base. Think of it as a small saddle-shaped pocket (its Latin name literally means “Turkish saddle”) that cradles the pituitary gland. The floor of this pocket is also the roof of the sphenoid sinus, one of the air-filled cavities behind your nose. A sheet of tough tissue called the diaphragma sellae stretches over the top like an incomplete lid, with a small opening for the pituitary stalk and blood vessels.
What makes this location so clinically important is the neighborhood. The optic chiasm, where your two optic nerves cross, sits just 1.5 to 8 millimeters above the front wall of the sella. On either side run the cavernous sinuses, which contain the internal carotid arteries and several cranial nerves controlling eye movement. Even a small mass growing in this tight space can press on these critical structures.
Types of Sellar Masses
Pituitary adenomas account for the large majority of sellar masses. They are classified by size: microadenomas are smaller than 10 mm, macroadenomas are 10 mm or larger, and giant adenomas exceed 40 mm. They’re also classified by whether they produce excess hormones. Functioning (secretory) adenomas overproduce one or more pituitary hormones, while nonfunctioning adenomas do not.
Other growths can appear in this region too. Craniopharyngiomas are benign tumors that develop from embryonic tissue near the pituitary stalk. Rathke cleft cysts are fluid-filled sacs left over from early development. Meningiomas, chordomas, and rarely metastatic cancers from elsewhere in the body can also present as sellar or parasellar masses.
How a Sellar Mass Causes Symptoms
A sellar mass can cause problems in two distinct ways: by pressing on nearby structures (mass effect) and by disrupting hormone production.
Vision and Nerve Problems
Because the optic chiasm sits directly above the pituitary gland, an upward-growing mass often compresses it. The hallmark result is bitemporal visual field loss, meaning you lose peripheral vision on the outer sides of both eyes. In one study of patients referred for surgery, 41% had this pattern. However, the visual effects aren’t always symmetrical. About 33% of patients with visual field loss had deficits in only one eye, and some experienced vertical or other unusual patterns of vision loss. Double vision can also occur if the mass extends sideways into the cavernous sinus and affects the nerves that control eye movement.
Hormonal Changes
Functioning adenomas overproduce specific hormones, and the symptoms depend on which one. A prolactin-secreting tumor (prolactinoma) can cause unexpected breast milk production, irregular periods, low sex drive, and hair loss. A growth hormone-producing tumor leads to acromegaly, with gradual enlargement of the hands, feet, and facial features. A tumor that overproduces the stress hormone ACTH causes Cushing disease, marked by weight gain (especially in the face and midsection), high blood pressure, and diabetes.
Even nonfunctioning masses can disrupt hormones by compressing healthy pituitary tissue. This can reduce the gland’s output across the board, leading to fatigue, low energy, mood changes, stunted growth in children, or low sex drive. Because these symptoms develop slowly and overlap with many common conditions, they’re often missed for months or years.
How Sellar Masses Are Diagnosed
MRI of the brain and sellar region, performed with and without a contrast agent called gadolinium, is the imaging study of choice. Thin slices in multiple planes let radiologists see the mass in detail and determine its relationship to the optic nerves and cavernous sinuses.
Many sellar masses are discovered incidentally on brain imaging done for an unrelated reason, such as a head injury or persistent headaches. These are called pituitary incidentalomas. Regardless of how the mass is found, a hormonal workup typically follows. This includes blood tests for prolactin, growth hormone and its marker IGF-1, cortisol (sometimes collected in a 24-hour urine sample), thyroid-stimulating hormone, and reproductive hormones. A formal visual field test is also standard to check for subtle peripheral vision loss you might not have noticed.
Treatment Approaches
Not every sellar mass needs immediate treatment. The approach depends on the type of mass, whether it produces hormones, and whether it’s causing symptoms or growing.
Monitoring Small, Inactive Masses
Nonfunctioning microadenomas (under 10 mm) that aren’t causing symptoms are often monitored with periodic MRI scans rather than treated right away. Guidelines recommend a follow-up MRI about one year after the initial diagnosis. If the mass hasn’t changed, subsequent scans become less frequent. For very small lesions under 5 mm that remain stable, further imaging may not even be necessary. Macroadenomas need closer surveillance: an MRI at 6 months after diagnosis, then annually for at least 3 years, because larger masses have a greater tendency to grow.
Medication for Prolactinomas
Prolactinomas are the one major exception to the “surgery first” rule. Dopamine agonist medications are the first-line treatment and work remarkably well. These drugs normalize prolactin levels in about 78% of patients overall, and in 86% of those with microprolactinomas. Even for larger prolactinomas, the biochemical cure rate with medication (77%) significantly outperforms surgery (57%). Surgery is reserved for the minority of patients who don’t respond to or can’t tolerate these medications.
Surgery
Surgery is recommended for nonfunctioning adenomas that are causing visual problems or growing on serial imaging, for functioning adenomas causing Cushing disease or acromegaly, and for acute pituitary apoplexy (sudden bleeding into the gland that causes severe headache and rapid vision loss). Other parasellar masses like craniopharyngiomas and meningiomas are also typically treated surgically if they’re symptomatic.
The standard approach is transsphenoidal surgery, which reaches the pituitary through the nasal passages and sphenoid sinus. Because the surgeon works through the nose, there are no external incisions or visible scars. The endoscopic version of this procedure, using a small camera for visualization, has become the preferred technique. Systematic reviews have found it to be safer than open surgical approaches, with lower complication rates, shorter hospital stays, and better visualization of the surgical field. Recovery is generally faster than with traditional brain surgery, though you’ll still need hormonal monitoring afterward to ensure the remaining pituitary tissue is functioning properly.