- Clinical science
Pituitary adenomas are benign tumors that often arise sporadically from the anterior pituitary gland. They are classified based on their size as microadenomas or macroadenomas, and whether they produce hormones as secretory (functional) and non-secretory (non-functioning) adenomas. Secretory adenomas produce the pituitary hormone of the corresponding cell type, which results in a state of hyperpituitarism. Non-secretory macroadenomas, however, destroy the surrounding normal pituitary tissue and result in hypopituitarism. Additionally, large macroadenomas compress the optic chiasm and can thus present with signs of mass effect such as bitemporal hemianopsia. The investigation of choice is a contrast-enhanced cranial MRI, which reveals an intrasellar mass. Assays of pituitary hormones are used to evaluate the patient for endocrine abnormalities, and perimetry is required to document visual field defects. Transsphenoidal surgical resection is the first-line therapy for most pituitary adenomas; however, non-secretory microadenomas generally only require follow-up, and prolactin-producing pituitary adenomas (prolactinomas) are best treated with dopamine agonists (e.g., bromocriptine, cabergoline). Pituitary irradiation is indicated only if the pituitary adenomas recur and/or if surgical therapy is contraindicated.
- Most cases occur sporadically.
- Some cases (∼ 5%) have a genetic/familial association.
- type 1
- Type of tumor according to size:
- Microadenoma: ≤ 10 mm
- Macroadenoma: > 10 mm
- Secretory pituitary adenomas (60%): hormone secretion → hyperpituitarism
|Type of secretory pituitary adenomas|| |
Relative frequency (as a percentage of all pituitary adenomas)
|Lactotroph adenoma (prolactinoma)||∼ 40%|
|Somatroph adenoma||∼ 15%||↑ Growth hormone → /|
|Corticotroph adenoma ( )||∼ 5%||↑ ACTH → secondary hypercortisolism|
|Thyrotroph adenoma||∼ 1%||↑ TSH → secondary|
- Non-secretory pituitary adenomas
|Type of pituitary adenoma||Secretory adenomas||Non-secretory adenomas|
Cranial contrast MRI (initial test) : reveals an intrasellar mass
- CT scan may be considered
- Hormone assays 
- Perimetry: to assess visual field defects
- (suprasellar mass): most commonly in children
- (parasellar mass)
- Lymphocytic histiocytosis …
The differential diagnoses listed here are not exhaustive.
- Non-secretory pituitary microadenomas (incidentalomas): no treatment (only follow-up)
- Other pituitary adenomas