Sellar Mass

Sellar masses (SMs) are adenoma bodies that are typically located on or around the pituitary gland, specifically near the sella turcica. Pituitary adenomas (PAs) account for the vast majority of SMs and are subdivided into nonfunctioning adenomas (NFAs) or functioning adenomas.

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 Masses 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 prolactinInability to breastfeed
Low GHShort stature in children, fatigue, increased adiposity and reduced exercise capacity
Low luteinizing hormone/follicle stimulating hormoneLow libido, sexual dysfunction, menstrual irregularities, vasomotor symptoms, infertility and osteoporosis
Low cortisolWeight loss, fatigue, muscle weakness, postural dizziness and salt craving
Low TSHFatigue, weight gain, cold intolerance, constipation and bradycardia
Low VPPolyuria & polydipsia
Table provided via Wilkinson M, Imran SA. Clinical Neuroendocrinology: An Introduction. 1st ed. Cambridge University Press; 2019:171-18

Table 2. Key features of common hormone oversecretion disorders

HyperprolactinemiaSexual 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
Table provided via Wilkinson M, Imran SA. Clinical Neuroendocrinology: An Introduction. 1st ed. Cambridge University Press; 2019:171-181.

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

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.