Nonfunctioning pituitary adenoma
A nonfunctioning pituitary adenoma is a benign pituitary tumor, usually of gonadotroph origin, that does not secrete a clinically excessive hormone and presents through mass effect (visual field loss, headache) or hypopituitarism rather than a hypersecretory syndrome. Diagnosis requires excluding hormone excess and screening for hypopituitarism; treatment is observation for a small asymptomatic incidentaloma or transsphenoidal surgery for mass effect, apoplexy, or growth on follow-up.
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What this article covers
- Overview
A nonfunctioning pituitary adenoma is a benign anterior pituitary tumor that does not produce a clinically evident hormone-excess syndrome, even though most are of gonadotroph origin and can…
- Epidemiology
Pituitary incidentalomas are common: microadenomas are found in 10% to 38% of MRIs performed for a nonpituitary reason, and macroadenomas in about 0.2% of such scans; most of these incidental lesions are nonfunctioning adenomas.
- Risk factors
No identifiable predisposing condition is found in most patients; sporadic tumorigenesis accounts for the majority.
- Pathophysiology
Nonfunctioning adenomas most often arise from gonadotroph lineage cells that retain the capacity to synthesize gonadotropins or their subunits but do not release enough intact hormone to cause a…
- Clinical features
Symptoms depend on tumor size and location and evolve slowly, since a nonfunctioning adenoma does not produce an acute hormone-excess syndrome.
- Differential diagnosis
Prolactinoma: shares mass-effect symptoms but is distinguished by prolactin typically more than 10 times the upper limit of normal, versus the mild stalk-effect elevation of a nonfunctioning tumor.
- Diagnosis
The diagnosis is established by demonstrating a sellar mass on pituitary MRI that lacks biochemical evidence of hormone excess; unlike a functioning adenoma, there is no single diagnostic hormone…
- Management
First, determine whether the tumor requires active intervention or can be observed: surgery is indicated for visual deficits related to the tumor, a mass that abuts or compresses the optic chiasm or…
- Complications
Vision loss, including permanent bitemporal hemianopsia or blindness, from untreated or recurrent chiasm compression.
- Prognosis
Asymptomatic patients with a small incidentaloma are unlikely to progress, which is why observation with periodic reassessment is appropriate rather than immediate surgery.
- Prevention
There is no primary prevention for sporadic nonfunctioning pituitary adenomas.
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Related articles
- Prolactinoma
Prolactinoma is a prolactin-secreting pituitary adenoma, the most common functional pituitary tumor, presenting with hypogonadism and galactorrhea from prolactin excess or with headache and visual loss from mass effect in larger tumors. Diagnosis requires an elevated prolactin with a pituitary mass on dedicated MRI after excluding pregnancy, medication effect, and hypothyroidism, and first-line treatment is a dopamine agonist, most often cabergoline, which lowers prolactin and shrinks the tumor without surgery in most patients.
- Acromegaly
Acromegaly is acral and soft-tissue overgrowth from chronic growth hormone excess, almost always caused by a GH-secreting pituitary adenoma, diagnosed with an elevated IGF-1 confirmed by failure of GH suppression on an oral glucose tolerance test. First-line treatment is transsphenoidal resection of the pituitary tumor, with somatostatin analogues, pegvisomant, or cabergoline for persistent disease.
- Pituitary apoplexy
Pituitary apoplexy is sudden hemorrhage or infarction of a pituitary adenoma causing severe headache, visual loss, ophthalmoplegia, and acute adrenocorticotropic hormone (ACTH) deficiency, and is a medical emergency. First-line treatment is immediate IV hydrocortisone given empirically before confirmatory testing when adrenal insufficiency is suspected, with urgent pituitary MRI and surgical decompression reserved for progressive visual loss.