Sellar Mass

History & Epidemiology

Sellar masses (SMs) are adenoma bodies that are typically located on or around the pituitary gland, specifically near the sella turcica.^1,2 Sellar masses are known to account for approximately 10% to 15% of all intracranial neoplasms.^3,4 and are responsible for a myriad of visual, neurological, and hormonal deficiencies.³ Pituitary adenomas (PAs) account for the vast majority of sellar masses and are subdivided into nonfunctioning adenomas (NFAs) or functioning adenomas.⁴

In the US, among major histology groupings, reported incidence rates were highest for tumors of the meninges (7.49 per 100,000), followed by tumors of the neuroepithelial tissue (6.60 per 100,000), tumors of the sellar region (3.12 per 100,000) and tumors of the cranial and spinal nerves (1.70 per 100,000).²

Sellar masses are reported to be found incidentally in 4 to 20 percent of CTs and 10 to 38 percent of MRIs, when imaging was performed for non-pituitary symptoms or reasons.⁹ In autopsy studies, the frequency of pituitary adenomas was approximately 10 percent.⁹ Among subcategories of sellar masses, NFAs were the most frequent sellar mass with an incidence rate of 2.34 per 100,000 cases and prevalence rate of 41.34 per 100,000 cases, followed by prolactinomas with a prevalence of 36.67 per 100,000 cases in Canada.⁵

Sellar Mass Causes & Risk Factors

PAs account for the majority of sellar mass formation primarily in the sellar/parasellar region of the brain and can be responsible for a sellar mass with suprasellar extension occurring. ⁵ Although not nearly as common, sellar mass formation can also be caused by pituitary hyperplasia, craniopharyngioma, meningioma, pituicytoma, germ cell tumors, sarcomas, chordomas, and lymphomas.^3,4 Cysts found in the sellar and/or suprasellar area, including Rathke’s cleft, arachnoid, and dermoid cysts, pituitary abscesses, arteriovenous fistula of the cavernous sinus, and several types of hypophysitis can also be a culprit for sellar mass formation, but are considered rare cases.³

Risk factors for sellar mass formation stem from a variety of conditions and pharmacological factors that result in PAs, accounting for over 80% of sellar masses.⁴ Medical conditions include multiple endocrine neoplasia type 1, McCune–Albright syndrome, Carney complex, sarcoidosis, autoimmune disorders, and mutations in the following genes: MEN1, Gs-alpha, and AIP.^3,4 Additionally, oral contraceptives, anti-psychotics, opioids and immunotherapy agents can cause significant pituitary hormonal dysfunction that will increase the likelihood of a PA.⁴

Sellar Mass Prognosis

By definition, a prognosis implies that the course of a disease follows a suggestible pattern and can be interpreted in a direct fashion. However, certain diseases and conditions, including sellar masses, do not follow such a pattern.

If left untreated, the sellar mass will most likely keep to normal size, however, a 10% to 20% growth has been noted to occur in a small population of case studies.⁶

Primary treatment of a sellar mass begins with surgical intervention of the pituitary.³ Given its location, transsphenoidal hypophysectomies have been identified as the most appropriate procedures for the removal of sellar masses, specifically in the presence of PAs.^1,3 In cases where the sellar mass is small enough, physicians are capable of performing stereotactic radiosurgery as a less-invasive alternative.¹ If necessary, radiation, pharmacological, or combination/cycling therapy can play a role.³ These are primarily utilized in diagnoses involving central hypoadrenalism, prolactin-secreting PAs, microprolactinomas, and Cushing’s disease.³ While surgery does provide the most promising outcomes for patients, persistent or recurrent disease may occur postoperatively, requiring life-long follow-up.⁶

Diagnostic Protocols & Physical Examination Findings

It is vital to ensure that a thorough physical examination is performed when determining whether or not a sellar mass is present. Key elements to focus on include features of hypopituitarism, hormonal over secretion, features of mass effect, current medications, and an extensive look at family history.⁴ The following tables provide specific criteria a physician should be attentive of:

Table 1. Key features of pituitary insufficiency

Low prolactin	Inability to breastfeed
Low GH	Short stature in children, fatigue, increased adiposity and reduced exercise capacity
Low luteinizing hormone/follicle stimulating hormone	Low libido, sexual dysfunction, menstrual irregularities, vasomotor symptoms, infertility and osteoporosis
Low cortisol	Weight loss, fatigue, muscle weakness, postural dizziness and salt craving
Low TSH	Fatigue, weight gain, cold intolerance, constipation and bradycardia
Low VP	Polyuria & polydipsia

Table 2. Key features of common hormone oversecretion disorders

Hyperprolactinemia	Sexual dysfunction, infertility and galactorrhea
GH (acromegaly)	Sweating, excessive snoring, voice change, acral enlargement, nerve entrapment, coarse features, diabetes, hypertension and sexual dysfunction
TSH (secondary hyperthyroidism)	features of thyrotoxicosis including tachycardia, palpitations, tremor, heat intolerance, sweating, diarrhea, weight loss and nervousness

Baseline hormonal screening tests are essential in all patients with sellar mass at initial presentation and further hormonal assessment is based upon determining the origination of sellar mass formation. A list of recommended baseline tests after an overnight fast include serum cortisol, serum TSH, serum thyroxine, prolactin, LH/FSH, estradiol/testosterone, and IGF-1.⁴ Of these screening tests, IGF-1 level is the most accurate single test for the diagnosis of acromegaly.³

After a thorough physical examination and hormonal assessment are conducted, it is imperative to move towards imaging procedures. MRIs with gadolinium-enhanced imaging will be the most beneficial diagnostic tool to determine the presence of a sellar mass.^1,3,4 In individuals where the use of gadolinium is contraindicated, such as renal impairment and pregnancies, unenhanced MRI imaging will suffice.³ The only situation in which the use of a CT scan would trump the use of an MRI is in a situation where there is suspicion of calcification in a craniopharyngioma or meningioma.³

Differential Diagnosis of Sellar Masses

There is no single characteristic, whether it be clinical, biochemical, or imagological, that allows for easy decisions in making a sellar mass diagnosis.⁷ Sellar masses may represent a true diagnostic challenge.⁷ The most common factor that will be useful in the differential diagnosis to determine the presence of a sellar mass is the spontaneous development of central diabetes insipidus.³ This occurs primarily if the formation of a sellar mass is caused by a craniopharyngioma tumor, a germ cell tumor, and/or metastatic disease.³ Central diabetes insipidus indicates that the lesion affects the hypothalamus or the stalk and is therefore not a pituitary lesion.³

Examples of non-pituitary differential diagnoses include, but are not limited to: cell rest tumors, germ cell tumors, gliomas, meningiomas, metastatic tumors, congenital-, cystic-, or vascular lesions, granulomatous, hypophysitis, and infections.⁸

References

1. Pituitary and Parasellar Tumors. Columbia Neurosurgery in New York City. Published April 8, 2021. Accessed September 15, 2022.
2. Dolecek TA, Propp JM, Stroup NE, Kruchko C. CBTRUS Statistical Report: Primary Brain and Central Nervous System Tumors Diagnosed in the United States in 2005-2009. Neuro-Oncology. 2012;14(suppl 5):v1-v49. doi:10.1093/neuonc/nos218
3. Snyder PJ. Causes, Presentation, and Evaluation of Sellar Masses. UpToDate. Published October 21, 2021. Accessed September 15, 2022.
4. Wilkinson M, Imran SA. Clinical Neuroendocrinology: An Introduction. 1st ed. Cambridge University Press; 2019:171-181
5. Snyder PJ. Incidentally discovered sellar masses (pituitary incidentalomas). UpToDate. Published March 21, 2021. Accessed September 29, 2022.
6. Al-Dahmani K, Mohammad S, Imran F, et al. Sellar Masses: An Epidemiological Study. Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques. 2015;43(2):291-297. doi:10.1017/cjn.2015.301
7. Sellar Masses. Endocrinology Advisor. Published January 9, 2019.
8. Ferreira AG, Silva TN, Luiz HV, Campos FD, Cordeiro MC, Portugal JR. Sellar Plasmacytoma Presenting with Symptoms of Anterior Pituitary Dysfunction. Endocrinology, Diabetes & Metabolism Case Reports. Published online November 24, 2017. doi:10.1530/edm-17-0102
9. Freda PU, Post KD. Differential Diagnosis of Sellar Masses. Endocrinology and Metabolism Clinics of North America. 1999;28(1):81-117. doi:10.1016/s0889-8529(05)70058-x

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Author Bio

Michael Gosden is a current Ph.D. fellow at Springfield College, MA. His major of study is Exercise Physiology with a focus in clinical sciences. He has obtained a BS from East Stroudsburg University and underwent an MS at Springfield College. Michael has worked primarily with patients in a variety of cardiac and pulmonary rehabilitation settings.

FAQs

What causes sellar mass?

Sellar masses are caused by various factors, including tumors (benign or malignant), cysts, infections, or inflammation due to autoimmune disorders such as sarcoidosis. In addition, some genetic conditions have been linked to increased risk for developing sellar masses.

What is the sellar region of the brain?

The sellar region of the brain is located near the base of the skull and consists of several vital structures, including the pituitary gland, hypothalamus, optic chiasm, and other parts. It controls many vital functions such as hormone release from the pituitary gland, body temperature regulation through signals sent to the hypothalamus, vision via signals sent to the optic nerve pathways, and other processes. A sellar mass is an abnormal growth or accumulation in this area that can cause various medical issues.

What are the visual symptoms of a sellar mass?

Visual symptoms associated with a sellar mass depend on its location within this region; however, they may include blurred vision, double vision, or decreased peripheral vision due to compression on surrounding tissues/structures (e.g., optic nerves). Other symptoms may include headaches/head pressure depending on size and location and hormonal disturbances if it involves disruption of normal function in nearby organs such as pituitary glands.

Which diagnostic test is conducted to determine suspected sellar mass?

Diagnostic tests used to determine suspected sellar mass typically involve imaging methods such as MRI scans which allow detailed visualization within this area; CT scans are also helpful but not necessarily preferred over MRI due to their higher radiation exposure rates with repeated use over time. Other tests that can provide information about potential causes include blood work on hormones released from nearby organs (pituitary) and biopsy if the tumor is suspected based on imaging results before a healthcare provider(s) establishes a treatment plan.