Pituitarpituitary neuroendocrine tumors) are benign tumors that arise sporadically from the anterior pituitary gland. They are classified as either microadenomas or macroadenomas according to their size, and as either secretory (functional) or nonsecretory (nonfunctioning) according to their ability to secrete hormones. Secretory adenomas produce the pituitary hormone of the cell type from which they arise, which results in a state of hyperpituitarism. Nonsecretory macroadenomas can destroy the surrounding normal pituitary tissue, which results in hypopituitarism. Additionally, large macroadenomas compress the optic chiasm; therefore, patients may present with signs of mass effect such as bitemporal hemianopsia. MRI sella with IV contrast is the gold standard imaging method for the pituitary and should reveal any intrasellar masses. Pituitary hormone assays are used to evaluate patients for endocrine abnormalities, and perimetry is used to identify visual field defects. Transsphenoidal hypophysectomy is the first-line therapy for most patients with symptomatic pituitary adenomas; patients with nonsecretory microadenomas generally only require follow-up (until they become symptomatic), and prolactin-producing pituitary adenomas (prolactinomas) should be initially treated with dopamine agonists (e.g., cabergoline, bromocriptine). Pituitary irradiation is indicated in recurrent pituitary adenomas and/or if surgical therapy is contraindicated.denomas (also known as
- Prevalence 
- Peak incidence: 35–60 years 
Epidemiological data refers to the US, unless otherwise specified.
- Most cases occur sporadically.
- Some cases (∼ 5%) have a genetic/familial association: 
- type 1
- Carney complex
- Familial isolated pituitary adenoma syndrome 
- Pituitary adenomas are well-circumscribed, intrasellar tumors with monomorphic, polygonal cells arranged in sheets or cords without any connective tissue and/or reticulin.
Tumor classification according to size
- Pituitary microadenoma: ≤ 10 mm
- Pituitary macroadenoma: > 10 mm
Tumor classification according to ability to secrete hormones
- Nonsecretory pituitary adenomas 
- Secretory pituitary adenomas: hormone secretion → hyperpituitarism
|Secretory pituitary adenomas|
|Lactotroph adenoma (prolactinoma) || |
|Somatroph adenoma|| || |
|Corticotroph adenoma ()|| |
|Thyrotroph adenoma|| || |
|Gonadotroph adenoma|| |
|Type||Secretory adenomas||Nonsecretory adenomas |
The diagnostic approach varies according to clinical presentation.
|Diagnostic approach for a suspected pituitary adenoma |
|Presentation||Initial evaluation||Further evaluation|
|Symptoms of mass effect to the pituitary|
|Symptoms of hypopituitarism or hyperpituitarism|| |
|Pituitary incidentaloma |
Hormone assays 
Indications for testing
- First-line tests for all patients with symptomatic endocrine dysfunction
- Pituitary mass detected on imaging
- Prior to planned pituitary surgery
Choice of studies
- Symptomatic patients: Studies are chosen according to clinical presentation.
- Asymptomatic patients: general screening
|Initial hormone studies for suspected pituitary endocrine dysfunction|
|Asymptomatic patients |
|Hypogonadism or absent lactation|
|Hyperthyroidism or hypothyroidism|
|Acromegaly or gigantism|| |
Imaging studies 
MRI sella with IV contrast (gold standard)
- Characteristic finding: intrasellar mass
- Potential additional findings 
- CT sella with IV contrast
- Visual field testing (e.g., perimetry) 
- Histopathology: Order markers of proliferation (e.g., p53) and pituitary hormones for resected pituitary adenomas, particularly if the adenoma is aggressive or recurrent. 
- Genetic testing: Genetic testing is not routinely recommended; consider in patients with a family history suggestive of potential genetic syndromes (see “Etiology”). 
- Assess patients for life-threatening and sight-threatening complications.
- Refer all patients to endocrinology.
|Initial treatment of pituitary adenomas |
|Tumor type||First-line treatment|
Prolactinomas (symptomatic or macroadenomas)
|Symptomatic nonsecretory adenomas|
|Asymptomatic nonsecretory adenomas|
Pituitary adenomas may bleed spontaneously, causing pituitary apoplexy (i.e., pituitary tumor apoplexy); this manifests with severe headaches, visual symptoms, cardiovascular collapse, and/or acute secondary adrenal insufficiency. 
Patients may be acutely unwell secondary to hormonal alterations; treat aggressively before starting definitive management.
Do not delay hydrocortisone treatment in patients with or .
Surgical management 
- Give patients with the following a hydrocortisone on the day of surgery:  of
- In patients with hypothyroidism, are recommended before surgery to achieve a euthyroid state (e.g., methimazole, propylthiouracil, beta blockers).
- Ensure that all patients who are referred to neurosurgery also receive an endocrinology consult.
- Procedure: transsphenoidal hypophysectomy 
Transsphenoidal hypophysectomy can alter ADH secretion, causing transient or permanent central DI and/or SIADH. In some patients, these alterations can occur sequentially in a biphasic pattern (i.e., DI followed by SIADH), or less frequently, in a triphasic pattern (i.e., DI followed by SIADH followed by DI). 
Prolactinomas: Dopamine agonists (cause the adenoma to shrink)
- First line: cabergoline 
- Second line: bromocriptine
- ACTH-secreting tumor (see “Cushing disease” for details)
- GH-secreting tumor (see “Acromegaly” for details)
- TSH-secreting tumor: somatostatin analogs (e.g., octreotide, lanreotide)
- Prolactinomas: Dopamine agonists (cause the adenoma to shrink)
- Asymptomatic microprolactinomas
- Asymptomatic nonsecretory adenomas
|Observation strategies for asymptomatic nonsecretory pituitary adenomas |
|Nonsecretory incidentalomas||Asymptomatic prolactinoma|
|Imaging studies (MRI)|| || |
|Hormone assays|| |
|Visual field testing|
- Intracranial neoplasms 
- Granulomatous disorders invading the sellar region or hypothalamus
- Carotid artery aneurysm
- Lymphocytic hypophysitis
The differential diagnoses listed here are not exhaustive.