Endocrinology · Pituitary Disorders
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Prolactinoma is the most common functional pituitary adenoma and presents with galactorrhea, amenorrhea, and infertility.
Bitemporal hemianopsia occurs due to mass effect compression of the optic chiasm by a macroadenoma (≥10 mm).
Dopamine agonists such as cabergoline or bromocriptine are the first-line treatment for prolactinomas regardless of size.
Acromegaly is caused by a growth hormone-secreting adenoma and is diagnosed by elevated IGF-1 levels followed by a glucose suppression test.
Cushing disease results from an ACTH-secreting pituitary adenoma, leading to hypercortisolism; the high-dose dexamethasone suppression test characteristically shows cortisol suppression (distinguishing it from ectopic ACTH), while screening uses 24h urinary free cortisol, late-night salivary cortisol, or low-dose dexamethasone.
Pituitary apoplexy is a medical emergency characterized by sudden onset headache, ophthalmoplegia, and altered mental status due to hemorrhage into the adenoma.
Transsphenoidal surgery is the first-line treatment for most symptomatic pituitary adenomas other than prolactinomas, which are primarily managed medically.
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A 34-year-old female presents with a 6-month history of irregular menses and bilateral milky nipple discharge. Physical examination reveals a bitemporal visual field deficit on confrontation testing. Laboratory studies show a significantly elevated serum prolactin level. A pituitary MRI confirms a 14 mm sellar mass compressing the optic chiasm.
What is the most appropriate initial management for this patient?
Cabergoline
The patient has a symptomatic prolactinoma (macroadenoma). Dopamine agonists such as cabergoline are the first-line treatment for prolactinomas, even in the presence of mass effect, as they effectively shrink the tumor.
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Etiology / Epidemiology
Most common pituitary mass; usually sporadic, rarely associated with MEN1 syndrome.
Clinical Manifestations
Presents with bitemporal hemianopsia due to optic chiasm compression or hormone hypersecretion.
Diagnosis
MRI of the brain with gadolinium is the imaging modality of choice; check serum prolactin levels.
Treatment
Cabergoline is first-line for prolactinomas; transsphenoidal surgery for mass effect.
Prognosis
High cure rate with surgery; pituitary apoplexy is an endocrine emergency needing immediate hydrocortisone, with surgery for severe or progressive visual loss.
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Epidemiology & Etiology
Pituitary adenomas are common, often incidental findings on imaging. While most are sporadic, they are a hallmark of Multiple Endocrine Neoplasia type 1 (MEN1). They are classified as microadenomas (<10mm) or macroadenomas (≥10mm); the WHO 2022 classification terms them pituitary neuroendocrine tumors (PitNETs).
Pertinent Anatomy
The pituitary gland sits within the sella turcica. Superior expansion leads to compression of the optic chiasm, causing classic visual field deficits. Lateral expansion can invade the cavernous sinus, potentially affecting cranial nerves III, IV, and VI.
Pathophysiology
Adenomas arise from monoclonal expansion of pituitary cells. Functional tumors secrete excess hormones (prolactin, GH, ACTH), while non-functional tumors cause symptoms via mass effect. Hyperprolactinemia suppresses GnRH, leading to secondary hypogonadism.
Clinical Manifestations
Patients present with bitemporal hemianopsia, headaches, and hormonal imbalances. Prolactinomas cause galactorrhea and amenorrhea. Pituitary apoplexy presents with sudden, severe headache, ophthalmoplegia, and altered mental status, requiring immediate corticosteroid replacement.
Diagnosis
MRI of the brain with gadolinium is the diagnostic test of choice. Laboratory evaluation should include serum prolactin, IGF-1, TSH with free T4, and morning cortisol. A prolactin level >200 ng/mL is highly suggestive of a prolactinoma.
Treatment
Cabergoline or bromocriptine are the first-line agents for prolactinomas. Dopamine agonists are rarely associated with valvular heart disease. Transsphenoidal surgery is indicated for non-prolactinomas. Prolactinomas causing visual field loss are still treated first with a dopamine agonist, which usually restores vision within days to weeks; surgery is reserved for dopamine agonist resistance or intolerance, apoplexy, or visual deficits that fail to improve on medical therapy.
Prognosis
Most patients achieve hormonal normalization with medical therapy. Pituitary apoplexy carries a high mortality risk if immediate stress-dose hydrocortisone is not given; urgent surgical decompression is reserved for severe or progressive visual loss or a declining level of consciousness, while milder cases can be managed conservatively. Long-term monitoring of visual fields and pituitary hormone axes is recommended.
Differential Diagnosis
Craniopharyngioma: calcified, cystic suprasellar mass
Empty Sella Syndrome: herniation of arachnoid into sella
Meningioma: dural tail sign on MRI
Hypophysitis: autoimmune inflammation, often postpartum
Metastatic disease: rapid progression, history of primary malignancy