Pituitary Tumors

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Background

Pituitary tumors are common neoplasms that constitute approximately 15% of all intracranial tumors.[1]  Among sellar neoplasms, pituitary adenomas are the most common, accounting for up to 90% of the tumors diagnosed in this region.[2]

The history of pituitary tumor biology is rich. Analysis of DNA extracted from the teeth of an Irish giant (7'7" tall) who lived from 1761 to 1783 revealed a mutation in the AIP gene – the same mutation found in four Northern Irish families with pituitary tumors. This suggests a shared genetic link dating back centuries. Interestingly, the giant's skull, examined in 1909 by renowned physicians Harvey Cushing and Sir Arthur Keith, showed an enlarged pituitary fossa, further supporting the diagnosis.[3]  Subsequent technological advances in genetics have expanded our knowledge of pituitary adenoma pathogenesis.

The clinical presentation of pituitary adenomas is broad. Some adenomas, called "functioning adenomas," secrete hormones that disrupt the body's endocrine system, leading to various conditions. Others, known as "nonfunctioning adenomas," do not produce hormones but can still cause symptoms by pressing on surrounding brain structures. Early diagnosis and treatment are crucial for managing these tumors and achieving optimal outcomes for patients.[1]

Pathophysiology

Around 95% of pituitary adenomas are sporadic.[4]  The molecular basis underlying pituitary adenoma pathogenesis encompasses several mechanisms: activating mutations, receptor signaling defects, chromosomal instability and DNA damage, as well as senescence.[4]

Multiple oncogene abnormalities have be involved in pituitary tumorigenesis, such as G-protein abnormalities, RAS gene mutations, or p53 gene deletions, mutations, and rearrangements.[4]  Nonfunctioning adenomas have been associated with hypermethylation of p16.[4]  Galectin-3 (Gal-3), a gene involved in cell growth and apoptosis, has been described in prolactinomas and corticotrophin adenomas.[5]  Additionally, familial pituitary adenomas, such as familial gigantism and acromegaly, have been associated with mutations in the aryl hydrocarbon-interacting protein gene (AIP).[4]  Hereditary pituitary adenomas have also been linked to multiple endocrine neoplasia (MEN) syndromes, such as MEN types 1 and 4.[6]

Although pituitary tumorigenesis is heterogeneous and recurrent cell-specific oncogenic mutations are uncommon, recurrent oncogene mutations have been reported in GNAS (somatotrophin adenomas), USP8 (corticotrophin adenomas), and rarely in NR3C1.[4]

Most of these tumors are benign, but certain factors involved in tumorigenesis may determine their aggressiveness. For instance, the presence of p53 correlates with more aggressive tumor behavior. Furthermore, mutations in AIP, MEN1, and GPR101 have been found to be more frequently invasive.[7] Likewise, the pituitary tumor transforming gene-1 (PTTG-1) is an oncogene that has also been implicated in pituitary tumors as a marker of invasiveness and recurrence.[4, 8]

Classification of pituitary tumors

Pituitary tumors are classified according to size as microadenomas (< 1 cm diameter) or macroadenomas (≥ 1 cm diameter). They are also classified based on staining characteristics as chromophobic or chromophilic tumors. The latter can be further subdivided using hematoxylin and eosin stains into eosinophilic or basophilic.[9]

Advances in electron microscopy and immunohistochemistry have enabled hormone identification in many adenomas previously classified as chromophobic. These techniques have also allowed for the characterization of specific hormone production in eosinophilic tumors and revealed that many tumors exhibit multihormonal production.

The 2022 WHO classification of endocrine and neuroendocrine tumors classifies sellar tumors based on cell lineage determined by transcription factors, hormones, and other biomarkers.[10]  Notably, "pituitary adenoma" is replaced with "pituitary neuroendocrine tumor" (PitNET).

PitNETs are categorized by the following cell lineages:

This classification identifies subtypes with more aggressive behaviors and replaces "pituitary carcinoma" with "metastatic PitNETs."[10] However, because this classification relies on histopathology requiring resection, the clinical PANOMEN 3 classification was developed to guide prognosis and therapy for both resected and unresected tumors. PANOMEN 3 utilizes an evidence-based score incorporating risk factors, including age, sex, phenotype, secretory status, hypopituitarism, size, mass effect, invasion, residual tumor, histopathology, and genetic syndromes.[11]

Clinical presentation pathogenesis

Clinical manifestations are due to the local effect of the mass and distant endocrine manifestations that can affect a variety of organ systems. These effects are due to lack or excess of a given stimulating hormone on the target organ.[1]  

Endocrine manifestations can be diverse. For example, even nonfunctioning adenomas can be associated with elevated prolactin blood levels. In this situation, hyperprolactinemia is secondary to stalk effect, which is the consequence of compression of the pituitary stalk by the sellar mass that interrupts the dopamine inhibitory signal from the hypothalamus to the prolactin-secreting cells of the adenohypophysis.[1]  

Pituitary macroadenomas can also cause distinct visual field defects. Bitemporal hemianopia, a typical pattern in these cases, arises from compression of the optic chiasm. A study using cadaveric specimens measured the comparative pressure gradients between nasal crossing and temporal uncrossed fibers. Two 30-gauge needles connected to pressure transducers and a digital pressure monitor introduced into the chiasm of donated cadaveric specimens acted as sensors. A pediatric Foley catheter was placed into the pituitary fossa and gradually inflated to simulate the effect of a pituitary mass. Results show that pressure was consistently higher in the central aspect of the chiasm than in the lateral chiasm.[12]  New engineering models of chiasmal compression (finite element modeling) may provide the possibility of measuring the degree of chiasmal compression in each patient based on MRI anatomic findings.[13]

Hormonal deficiencies - Clinical effects

Growth hormone deficiency [1]

Gonadotrophin deficiency [1]

Thyrotropin deficiency - Malaise, weight gain, lack of energy, cold intolerance, and constipation[1]

Corticotrophin deficiency [1]

Panhypopituitarism - Refers to deficiency of several anterior pituitary hormones; may occur in a slowly progressive fashion (eg, pituitary adenomas)[1]

Hormonal overproduction - Clinical effects

Prolactin [1]

Growth hormone [1]

Cushing disease [1, 14]

Epidemiology

Frequency

Pituitary tumors represent 10%–15% of all intracranial tumors.[1, 15]  Whereas incidental pituitary tumors are found in approximately 10% of autopsies and neuroimaging studies of healthy subjects,[15, 16, 17]  clinically evident pituitary adenomas are present in 1 of 11,000 subjects in the general population.[15, 18, 19, 20, 21, 22, 23, 24]  The relative frequency of clinically evident pituitary adenomas is approximately 41%–62% in prolactinomas, 15–48% in clinically nonfunctioning adenomas, 6%–14% in somatotroph adenomas, 2–6% in corticotrophin adenomas, and approximately 1% in thyrotroph adenomas.[15, 18, 19, 20, 21, 22, 23, 24]

The incidence of clinically evident pituitary adenomas has been estimated to be 40 per million individuals per year.[21, 25, 26]  The annual incidence of pituitary adenomas per 1 million individuals is estimated to be in the range of 16 to 26 for prolactinomas, approximately 10 for somatotroph adenomas, and 1.6 for corticotrophin adenomas.[1, 4, 20, 27, 28]  However, it is important to note that these rates can vary based on population demographics and geographic location.

Demographics

Among patients with a clinically evident pituitary adenoma, 62%–77% are women.[15, 18, 19, 20, 21, 22, 23, 24]  However, sex distribution is influenced by the type of pituitary adenoma and age.

Microprolactinomas have a female to male ratio of 20:1. Likewise, annual incidence of prolactinomas is higher in women than in men: 24–37 vs 7.6–9 per million, respectively. Nevertheless, after menopause, prolactinoma incidence is similar in both sexes.[4, 22, 25, 26]  Cushing disease is also more frequent in women with a female-to-male ratio of 3:1.[29]  On the contrary, nonfunctioning adenoma and acromegaly have similar frequency among males and females[4, 30]

Pituitary adenoma diagnosis predominates in middle-aged and elderly adults. However, its diagnosis can occur at any age. Peak acromegaly diagnosis occurs at age 40 to 60 years, prolactinoma in women usually predominates at age 25 to 40 years, and Cushing disease disproportionally affect young women.[4]

Mortality/Morbidity

Mortality rate related to pituitary tumors is low. Advances in medical and surgical management of these lesions and the availability of hormonal replacement therapies have contributed to successful management. Nevertheless, pituitary apoplexy is a life-threatening complication.

Because of cardiometabolic and respiratory comorbidities, acromegaly standardized mortality ranges from 1.41 to 1.45.[4, 31, 32, 33]  Standardized mortality ratio in patients with active Cushing disease is 4 to 16 times higher compared to the general population, secondary to stroke and coronary disease[4, 34]  Prolactinomas have not reported an increase in standardized mortality ratio.[35]

Morbidity associated with macroadenomas may include permanent visual loss, ophthalmoplegia, and other neurological complications. Tumor recurrence after surgical removal may also occur. Central nerve system metastases and, rarely, distant metastases can occur with pituitary tumors.[4]

Endocrine abnormalities are amenable to correction. However, damage in many organ systems as a result of longstanding uncorrected deficiencies may be irreversible. Additionally, overtreatment with glucocorticoids or thyroid hormones in patients with hypopituitarism may lead to cardiovascular and bone comorbidities.[4]

Prognosis

Visual prognosis

Visual field improvement has been reported in 79–95% of patients undergoing pituitary adenoma resection, and visual acuity improvement in 45–86%.[36]

The pattern of visual function recovery depends on the severity of the anterior visual pathway neuronal dysfunction:

Optical coherence tomography (OCT) can be used as a tool for predicting visual function recovery after pituitary tumor treatment. Normal macular ganglion cell-inner plexiform layer (mGCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thickness have been associated with a better postoperative visual outcome. OCT cutoff values are difficult to determine given the variation in values depending on the machine manufacturer used. Average pRNFL thickness below 75 to 81 um, and average mGCIPL thickness below 67 um have been associated with a worse visual outcome.[38]

Tumor recurrence

A high mitotic index, a Ki67 index greater than 3%, and histological subtypes such as sparsely granulated somatotroph adenomas, silent corticotrophin adenomas, Crooke cell adenomas, plurihormonal PIT1-positive tumors, and lactotroph macroadenomas in men have been suggested as potential prognostic pathological markers for aggressiveness.[7]  Additionally, an evidence-based score, PANOMEN 3, has been proposed to assess prognosis in patients with resected and unresected adenomas.[11]

Approximately 30% of resected adenomas have persistent progressive growth in the next 4 years after surgery.[1]

A meta-analysis that included 17,509 patients with pituitary adenomas treated surgically showed a 5-year postoperative recurrence rate of 4% in somatotroph adenomas, 11% in corticotroph adenomas, 12% in nonfunctioning adenomas, and 18% in prolactinomas.[39]

Pituitary carcinoma

The presence of metastasis secondary to pituitary carcinomas can occur. However, its prevalence is extremely low. Pituitary carcinomas constitute less than 0.1% of all anterior pituitary tumors.[7]

Patient Education

Successful management of pituitary adenomas requires a highly motivated and compliant patient.

Hormone-replacement therapy is demanding, and a noncompliant patient is at risk for complications due to misuse of these agents.

Interaction of a team of specialists is required to manage these lesions. One of the specialists should serve as team leader and coordinate the patient's care.

Most patients with visual field defects improved visual function after transsphenoidal surgery (TSS).[36, 40]  However, the degree and rate of visual recovery varies among patients and is influenced by multiple factors.[36]

Prompt reporting of new symptoms is important in addition to routine multidisciplinary follow-up visits.

The frequency of follow-up visits depends on the presence of residual tumor, visual deficit, hormonal needs, history of radiation therapy, or other complicating circumstances.

History

The clinical presentation of a pituitary macroadenoma relates to its mass effect and pressure on surrounding structures, as well as to hormone derangement secondary to hormonal deficiency or overproduction (see Pathophysiology).

Physical

Headaches can occur in 33%–72% of patients with pituitary adenomas.[36, 41]

Visual dysfunction is a common complaint in patients with pituitary adenoma who have optic chiasmal compression,[42]  often reported as blurred vision or decreased peripheral vision. It occurs in 38%–72% of patients who undergo surgical decompression. It develops secondary to anterior visual pathway compression by the pituitary tumor, usually chiasm. However, depending on tumor size and patient´s anatomy (pre or post fixed chiasm), optic nerves and optic tracts can also be involved, causing different visual field defect patterns (see Physical Examination).

Diplopia occurs in 2%–10% of patients secondary to invasion of the oculomotor nerves (third, fourth, and sixth cranial nerves) within the cavernous sinus.[36]  Furthermore, nonparalytic binocular diplopia can also occur in patients with pituitary adenoma with bitemporal hemianopia due to Hemifield slide phenomenon.[43]  Hemifield slide phenomenon is a horizontal or vertical binocular dissociation of the remaining visual fields secondary to significant overlap reduction between the temporal Hemifield of one eye with the nasal Hemifield of the contralateral eye. It can lead to diplopia in the absence of muscle paresis, allowing an underlying phoria to manifest as a tropia.[36, 43]

Oscillopsia can also be a complaint in patients with pituitary adenoma with nystagmus. Seesaw nystagmus, which is characterized by involuntary pendular oscillations of cycles of elevation-incyclotorsion in one eye with synchronous depression-excyclotorsion in the contralateral eye, can be associated with chiasm compression as well as rostral midbrain lesions.[36]

Difficulty performing precise manual tasks can occur in patients with pituitary adenomas who have bitemporal hemianopia. During convergence, temporal field defects from both eyes overlap, creating a triangular blind area behind the fixation point which causes loss of depth perception.[44]

Decreased sensation in the forehead and cheeks can be reported secondary to first and second branch trigeminal nerve involvement within the cavernous sinus.[36]

Cerebrospinal fluid (CSF) leak causing rhinorrhea has been described after surgical or medical treatment of macroadenomas. However, cases of spontaneous CSF leak have also been reported.[45]

Physical Examination

Neuro-ophthalmologic examination

Visual acuity is often decreased due to optic nerve involvement.

Pupillary light reaction can be abnormal. Relative afferent pupillary defect (RAPD) can be present due to unilateral or asymmetric bilateral optic nerve compression, invasion of the optic tract (RAPD would be contralateral), or asymmetric involvement of the nasal crossing fibers at the chiasm. In the same way, a dilated pupil with poor reaction to light in the absence of RAPD occurs with compression of the cranial nerve in the cavernous sinus. Pupil size inspection is relevant since anisocoria can occur because of third cranial nerve palsy (ipsilateral mydriasis associated with upper eyelid ptosis and altered ocular motility), or sympathetic fiber involvement causing Horner syndrome (ipsilateral miosis, associated with upper and lower eyelid ptosis) in the setting of macroadenoma extension into the cavernous sinus.[36, 42, 46]

Optic chiasm anatomy influences the type of visual field defect. When the optic chiasm lies over the diaphragm sellae, bitemporal hemianopia is the most common visual field defect.[42]  If the optic chiasm is prefixed, located over the tuberculum sellae (15%–20%), bitemporal hemianopic scotomas (due to damage to macular fibers in the posterior portion of the optic chiasm) or homonymous hemianopia secondary to optic tract involvement are more frequent.[42]  Additionally, if optic chiasm post fixed, located over the dorsum sellae (4%), anterior chiasmal syndrome and monocular visual field defects are more frequent.[42]

Color vision can also be affected. Decreased color vision is frequent, along with decreased visual acuity, in pituitary macroadenomas with compressive optic neuropathy. Moreover, confrontation peripheral color vision testing used to detect bitemporal red desaturation due to optic chiasm compression. This can be tested easily at bedside.[36, 42]

Visual field defects

Pituitary adenomas are associated with different types of visual field defects. Optic chiasm compression usually does not occur until pituitary adenomas extend 8 mm over the diaphragm sellae.[36]  Although confrontation visual field testing should be performed in patients with sellar lesions, automatic static perimetry is more sensitive to defect subtle visual field defects.[47]

Ophthalmoscopic examination

Optic atrophy occurs in patients with pituitary adenomas with anterior visual pathway compression due to retrograde axonal degeneration. Bilateral horizontal-oriented atrophy, also known as bow-tie atrophy or band atrophy, can occur in optic chiasm compression. This pattern occurs due to involvement of fibers from the nasal retina of both eyes and their arrangement at the optic nerve head. Peripheral nasal fibers enter the nasal sector of the optic disc, while the nasal macular fibers enter the temporal sector, forming an horizontal disposition of nasal fibers within the optic disc.[42] Optic neuropathy atrophy can also associate increased cup-to-disk ratio resembling a glaucomatous optic atrophy.[51]

Papilledema is exceptional, and mainly seen in patients with sellar lesions extending into the third ventricle causing hydrocephalus and raised intracranial pressure, or rarely in pituitary apoplexy.[36, 52]

Endocrine dysfunctions

These abnormalities may be present in isolation or in association with physical changes associated with endocrine dysfunction.

Prolactinomas

In females, galactorrhea may be present on clinical examination. Women undergoing an infertility evaluation frequently have a prolactinoma.

In males, galactorrhea is infrequent; testicles are decreased in size and may be soft to palpation.

Acromegaly

A multitude of typical clinical signs become evident by comparing the current facial appearance with prior photographs.

These changes include large hands and feet (with thick fingers and toes) and coarse facial features with frontal bossing. Women may appear masculinized. Other findings might include prognathism, carpal tunnel syndrome, and voice quality changes.

Cushing disease

Findings are prominent and include obesity, centripetal fat deposition, proximal myopathy, moon facies, buffalo hump, posterior subscapular cataracts, arterial hypertension, bruises, and skin striae.

Hypopituitarism

Chronic hypopituitarism results in hypotension, generalized weakness, hypothermia, malaise, and depression.

Acute sudden hypopituitarism (ie, pituitary apoplexy) is associated with shock, coma, and death.

Laboratory Studies

Initial endocrine evaluation

Prolactin test

Serum prolactin levels should be measured in any patient with a suspected sellar or suprasellar mass. If elevated, investigate the possibility of pharmacologic and other factors prior to ordering extensive neuroimaging studies.

Generally, a single elevated prolactin level may confirm the diagnosis. Minor elevations may be somewhat difficult to interpret since there are multiple causes of hyperprolactinemia. The first level obtained serves as a baseline and guides the course of dopamine-agonist therapy.

Serum prolactin level > 200 mcg/L in a patient with a macroadenoma greater than 10 mm in size is diagnostic of a prolactinoma. Levels below that range in a macroadenoma suggest hyperprolactinemia secondary to hypothalamic compression.

Acromegaly diagnosis

Growth hormone test

Growth hormone (GH) levels are elevated in acromegaly but can fluctuate significantly.

Intravenous (IV) GH levels every 5 minutes for 24 hours may show consistent elevation of GH. This is not a practical diagnostic method but does indicate that a single GH value is not sufficient to make a diagnosis.

Serum insulinlike growth factor 1 (IGF-1) level is the best endocrinologic test for acromegaly. IGF-1 reflects GH concentration in the last 24 hours. Technical factors may limit its usefulness in some laboratories.

Oral glucose tolerance test (OGTT)

The oral glucose tolerance test is the definitive test for the diagnosis of acromegaly; a positive result is the failure of GH to decrease to < 1 mcg/L after ingesting 50–100 g of glucose.

Cushing Disease/Syndrome testing

Urine test

Twenty-four-hour urine is collected to measure free cortisol. Usually requires two baseline values.

Dexamethasone suppression test

The physiological basis of this test is a decrease in adrenocorticotropic hormone (ACTH) secretion by the pituitary because of exogenous glucocorticoid administration. One mg of dexamethasone is administered and serum cortisol level is measured the next morning; it should be < 138 nmol/L (ie, < 5 mcg/dL).

Standard low-dose dexamethasone: Two-day baseline serum and urine cortisol levels are determined. The patient is then given 4 doses of 0.5 mg of dexamethasone at 6-hour intervals. Normal suppression is a serum cortisol level of < 138 nmol/L or a urine level of less than 55 nmol/L.

If cortisol levels are increased, corticotrophin-releasing factor (CRF) in a dose of 100 mcg can be given to differentiate between Cushing disease and other causes of hypercortisolism (ie, Cushing syndrome). With pituitary adenomas, elevated cortisol secretion increases over the baseline.

High-dose dexamethasone suppression confirms diagnosis of a pituitary adenoma. It suppresses the pituitary gland even in the presence of an adenoma. If cortisol levels remain unchanged, the cause of increased cortisol is not a pituitary adenoma.

Metyrapone test

Metyrapone inhibits synthesis of cortisol. Patients with pituitary tumors remain responsive to low levels of cortisol, prompted by metyrapone administration, with increased secretion of cortisol precursors (ie, 11-deoxycortisol).

ACTH test

The serum concentration of ACTH is higher than normal (> 5.5 pmol/L at 9 am and > 2.2 pmol/L at midnight).

At times, venous sampling of ACTH from the petrosal sinuses by means of cerebral venography may be valuable when making the diagnosis is difficult.

Corticotropin-releasing factor (CRF) test

Baseline petrosal sinus levels of CRF distinguish patients with Cushing disease from those with ectopic ACTH secretion.

Other pituitary hormone assessments

Glycoprotein hormones

These include thyroid-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone.

Pituitary adenomas that are associated with thyroid-stimulating hormone (TSH) hypersecretion are uncommon. These patients have increased T3 and T4 levels, hyperthyroidism, and goiter with inappropriately high levels of TSH.

Increased follicle-stimulating hormone (FSH) levels may be apparent in the histologic examination of a pituitary adenoma in patients without apparent preoperative endocrine abnormalities and in some patients with hypogonadism.

Increased luteinizing hormone (LH) levels occur in patients with hypogonadism. The secreted hormone is not intact LH, and serum testosterone levels are not increased.

Free alpha and beta subunits of FSH are unexpectedly secreted by pituitary tumors that are thought to be inactive. A high percentage of these tumors have a paradoxical release of FSH subunits in response to TRH stimulation (200 mcg). Rarely, these tumors are associated with precocious puberty or resumption of bleeding in a postmenopausal woman.

The initial screening endocrine tests should include levels of prolactin, IGF-1, LH, FSH, TRH and alpha subunit, cortisol, and T4; men should have testosterone level checked.

Pituitary apoplexy

CSF may be xanthochromic, with crenated RBCs and high protein level.

Imaging Studies

Magnetic resonance imaging (MRI)

MRI of the brain and sellar region with and without gadolinium contrast is the imaging study of choice for the evaluation of sellar and parasellar lesions. Multiplanar thin sections provide axial, coronal, and sagittal sections of the sellar contents, as well as the relationship between the lesion and the anterior visual pathway. Pituitary adenomas have variable T2 signal and mild to moderate enhancement on post-contrast imaging. Sellar expansion and inability to separate the tumor from the pituitary gland are helpful features to identify pituitary adenomas.[54, 55]

Intraoperative MRI (iMRI)

In cases of transsphenoidal surgery (TSS), iMRI can be invaluable for assessing the extent of tumor resection in real time. In one study evaluating patients with pituitary adenoma who underwent TSS, intraoperative high-field magnetic resonance imaging (iMRI) evaluated extent of tumor removal during the surgical procedure. Use of iMRI allowed wider resections in cases in which suspicious tumor remnants were detected after total resection. According to the researchers, incomplete removal of resectable pituitary adenomas was avoided in many cases by identifying the location of the tumor remnants. Moreover, in cases in which complete resection is not possible, further treatment can be planned earlier, without having to wait for the conventional postoperative MRI scans to be performed.[56]

Computed tomography (CT)

CT scan of the brain with sellar images with fine cuts between 3 mm and 5 mm is possible in patients with MRI contraindications. It is helpful to detect tumor calcifications, typically seen in craniopharyngiomas. However, the detail is inferior to that of MRI.[57]

Cerebral angiography

Cerebral angiography is no longer performed routinely in the workup of sellar mass lesions unless vascular lesions are suspected.

Other Tests

Visual field testing

Visual field testing with static automated perimetry can be used to assess the presence of anterior visual pathway compression by pituitary adenomas, as well as monitor for tumor progression based on afferent visual function. The Carl Zeiss Humphrey Field Analyzer is one of the most used static automatic perimetry devices in clinical practice. It has been shown that algorithms evaluating the central 24 degrees of vision perform as well as those assessing the central 30 degrees while reducing the time of examination.[58]

Optical coherence tomography (OCT)

Visual processing in the retina activates photoreceptors, which relay signals to bipolar cells and retinal ganglion cells (RGCs). RGC cell bodies reside in the inner retina, while their axons form the retinal nerve fiber layer (RNFL) and optic pathways, synapsing in the lateral geniculate nucleus.

OCT allows precise measurement of RNFL thickness at the peripapillary region (pRNFL) and the ganglion cell-inner plexiform layer complex (mGCIPL) at the macula. Compression of the optic chiasm by pituitary tumors leads to retrograde axonal degeneration, causing RGC apoptosis. This results in early thinning of the mGCIPL (3–4 weeks) and pRNFL (4–6 weeks), making OCT essential for detecting anterior visual pathway compression in pituitary macroadenomas.[38]

The pattern of RNFL and GCIPL thinning on OCT can also aid in localizing lesions along the visual pathway. For example, optic chiasm compression typically causes bilateral hemi-nasal thinning of the mGCIPL, while pRNFL may show nasal and temporal thinning. OCT is also valuable for predicting visual outcomes based on pRNFL and mGCIPL thickness.[38]

Optical coherence tomography angiography (OCT-A)

OCT-A is an advanced OCT technique that visualizes the retinal microvasculature. Studies indicate a decrease in retinal microvasculature in cases of chiasmal compression.[38, 59]

Combining visual field testing and OCT

Visual field testing and OCT are complementary diagnostic tools, frequently used together for evaluating patients with pituitary adenomas:

A thorough understanding of both visual field testing and OCT results is crucial for accurately evaluating patients with pituitary adenomas, as they provide different insights into disease status and progression.

Procedures

Petrosal sinus sampling is used selectively in cases of suspected adrenocorticotropic hormone (ACTH)- or thyroid-stimulating hormone (TSH)-producing adenomas. This procedure is particularly valuable when imaging findings are inconclusive or when there is a need to distinguish between pituitary and ectopic sources of hormone production.

Cerebral angiography is occasionally performed to rule out vascular lesions that may present with similar features to pituitary adenomas. This includes evaluating for conditions such as a thrombosed aneurysm that can mimic a pituitary tumor on imaging.

Histologic Findings

Pathologic examination of pituitary tumors resected during surgery is essential for accurate diagnosis. Routine assessments include standard histologic examination, electron microscopy, and immunohistochemistry, which help correlate findings with clinical and imaging data. Pathology can also reveal nonpituitary lesions that mimic pituitary tumors. However, distinguishing between hyperplasia and adenoma can be challenging in some cases. The histologic characteristics of pituitary adenomas are further discussed in the pathophysiology section.

Approach Considerations

Managing pituitary adenomas requires a multidisciplinary team, ideally comprising specialists in endocrinology, neurosurgery, neuro-ophthalmology, radiation oncology, neuroradiology, neuro-oncology, and neuropathology. Treatment options include medical therapy, surgery, and radiation therapy, with the choice of modality depending on various factors such as tumor type, size, location, and the patient’s overall health. As a result, treatment is tailored to each patient to achieve the best outcomes.

Medical Care

Prolactinomas

Dopamine agonist therapy is the first line of treatment in patients with prolactinoma.[1, 15, 53]  Tumor shrinkage, improvement in visual field abnormalities, and resolution of symptoms associated with hyperprolactinemia are achieved in many patients with this treatment.[1, 15, 53, 62]  Both cabergoline and bromocriptine are dopamine agonists used in the treatment of prolactinomas. Cabergoline is preferred because of its longer half-life, greater efficacy, and better tolerance. Side effects secondary to dopamine agonist treatment include gastrointestinal symptoms, orthostatic hypotension, and impulse control disorder. Valvular disease is a rare complication of chronic treatment with cabergoline.[62]  Therefore, periodic echocardiography is indicated in these patients. Withdrawal may be considered after a minimum of two years if there is complete tumor regression and normalized prolactin levels. MRI should be repeated 3–6 months after treatment initiation to assess response.

Acromegaly

Medical treatment is used in patients with persistent or recurrent acromegaly post surgery, or preoperatively in patients who are poor surgical candidates or require improved surgical outcomes.[1, 15, 63]

Pituitary-targeted therapy

Growth hormone receptor antagonist

Pegvisomant blocks GH receptor activation, lowering IGF-1 levels. It can be a first- or second-line treatment for persistent/recurrent acromegaly. Poor response predictors include younger age, female sex, obesity, and higher baseline IGF-1 levels. Side effects, occurring in fewer than 3% of patients, include potential tumor growth or elevated liver enzymes.

Cushing disease

Medical treatment is recommended for severe hypercortisolism preoperatively, recurrent/persistent disease after surgery, or when surgery is contraindicated. The aim is to decrease cortisol secretion. Medical treatment is often used alongside radiation therapy until effects of the latter manifest.[1, 15, 62]

Pituitary-targeted therapy

Adrenal steroidogenesis inhibitors

Fast and effective control of hypercortisolism, using drugs like etomidate, ketoconazole, levoketoconazole, osilodrostat, metyrapone, and mitotane.[62]

Glucocorticoid receptor antagonists

Mifepristone blocks peripheral glucocorticoid action.[62]

Combination therapy

Often required for comprehensive control of hypercortisolism.

Thyrotrophinomas

Medical therapy is used in cases of persistent hyperthyroidism or residual tumor following surgery.[1, 15, 62]

Pituitary-targeted therapy

Antithyroid medications

These include methimazole and propylthiouracil to manage hyperthyroidism.

Replacement therapy

Hormone replacement therapy for any absent or decreased hormones can be provided as needed.

All hormone-based treatments should be directed and monitored by a consulting endocrinologist to ensure appropriate management.

Surgical Care

Pituitary surgery has evolved since the days of Harvey Cushing’s research and his pioneering development of the sublabial and transcranial methods of accessing the sella. Surgical approaches for pituitary adenomas can be categorized as transcranial or extracranial.

Transcranial approaches consist of subfrontal and pterional (frontotemporal) approaches. They are less common and reserved for patients with contraindications to transsphenoidal surgery (TSS) or those with large extrasellar tumors. Extracranial approaches include microscopic TSS (transnasal, sublabial) and endoscopic endonasal TSS, which is a commonly used technique.[64]

Transsphenoidal surgery

Microscopic and endoscopic TSS are the most frequently used surgical approaches for resecting pituitary tumors. A meta-analysis comparing microscopic and endoscopic TSS in patients with pituitary adenoma showed no difference in gross tumor removal and hormone-excess secretion remission between these approaches. However, endoscopic TSS was associated with less incidence of diabetes insipidus, hypothyroidism, and septal perforation.[65]  Follow-up MRI should be performed 3–6 months postoperatively to establish a new baseline.

Nonfunctioning adenomas

TSS should be performed in patients with nonfunctioning adenomas if there is mass effect causing hypopituitarism or vision loss, tumor size greater than 10 mm, anterior visual pathway compression, or progressive tumor growth.[15, 17, 66]

Prolactinomas

Although medical treatment is usually the first-line treatment in patients with prolactinomas, TSS is also a reasonable first-line treatment in select patients.  TSS has a success rate of 92% for patients with microprolactinomas, allowing them to avoid prolonged dopamine agonist therapy.[1, 15] In contrast, TSS is less effective for macroprolactinomas, with a success rate of about 70% and a higher recurrence risk compared to microprolactinomas.[1, 15] For patients with prolactinomas who do not respond to medical therapy, adjuvant treatment with TSS or radiation is recommended. TSS is also preferred if rapid decompression of the visual pathway is necessary.

Acromegaly

TSS is first-line treatment in patients with acromegaly. It reduces growth hormone (GH) levels to below 5 mcg/L in approximately 60% of cases.[1, 15]  However, surgical remission rates vary, with success in 40–60% of patients with macroadenomas and 75–90% in those with microadenomas.[62]  For patients with persistent or recurrent adenomas, adjuvant therapy such as medical treatment, radiation, or repeat surgery is recommended.[1, 15, 63]

Cushing disease

TSS with selective adrenalectomy is first-line treatment in patients with Cushing disease. Remission is achieved in approximately 70–80% of microadenomas,[62]  and recurrence in 10%.[1]  In persistent or recurrent disease after TSS, adjuvant medical treatment and radiation therapy is recommended.[1, 15]

Adrenalectomy is a surgical option to reverse hypercortisolism. However, it is associated with the development of pituitary enlargement and a corticotropin-secreting adenoma known as Nelson's syndrome.[1]

Thyrotroph adenomas

TSS is first-line treatment for achieving total remission in approximately 65% of patients.[1, 15]

Radiation Therapy

Radiation therapy (RT) is a second- or third-line treatment used in residual or recurrent, functioning and nonfunctioning, pituitary adenomas.[15]  It is usually delivered as fractionated stereotactic radiotherapy (FSR), or as a single fraction radiotherapy in small tumors distant from the optic chiasm to avoid radiation-induced optic neuropathy. RT is used after surgical and medical treatment in patients with somatotroph adenomas, thyrotroph adenomas, and prolactinomas. Long-term control greater than 95% at 5 years has been reported in patients with pituitary adenomas treated with FSR.[66]  RT may help to control Cushing disease, however, it is associated with a relapse rate of approximately 30%.[1]

Complications

Complications occur throughout the clinical course of patients with pituitary adenomas and some of them related to their treatments.

Classic pituitary apoplexy

Classic pituitary apoplexy is a rare life-threatening condition characterized by headache, visual loss, ophthalmoplegia, and altered mental status, in the setting of sudden pituitary gland hemorrhage or infarction.[67]  One study evaluating patients with pituitary apoplexy showed that headache was the most common symptom in 87% of their cases, visual loss in 56%, ophthalmoplegia in 45%, and altered level of consciousness in 13%. Hypopituitarism was present in 73% of patients and diabetes insipidus in 8%.[68]  The acute panhypopituitarism can be associated with shock, and hypothalamic-brainstem compression can lead to coma and even death. Therefore, patients with pituitary apoplexy require a tertiary care center with access to an intensive care unit.

Subclinical pituitary apoplexy

Subclinical pituitary apoplexy or asymptomatic pituitary hemorrhage and/or infarction is frequent on routine imaging. Most cases occur in patients without a prior known diagnosis of pituitary adenoma.[67] Several mechanisms have been identified as triggers for pituitary apoplexy, including reduced blood flow in the pituitary gland (hypotension or sudden increase in intracranial hypertension), acute increase in blood flow in the pituitary gland, stimulation of the pituitary gland through increased estrogen states or other secretagogues, and anticoagulated states.[67]

MRI is the preferred diagnostic method, although CT is an alternative if MRI is unavailable.

Surgical decompression is often necessary for patients with rapidly worsening vision, altered mental status, or hypothalamic compression. Stable patients may be managed conservatively.

Transsphenoidal surgery (TSS)

Complications related to transsphenoidal surgery (TSS) include:[69]

Radiation therapy

Although rare, radiation therapy can lead to significant complications in patients with pituitary adenomas.[71]  Potential effects include hypothalamic necrosis, radiation-induced optic neuropathy, and radiation-induced oculomotor cranial neuropathies (affecting cranial nerves III, IV, or VI). Another potential complication is ocular neuromyotonia, which involves episodic, involuntary, sustained contraction of one or more extraocular muscles, often triggered by sustained gaze in a specific direction. It results from hyperactivity of motor nerve fibers and can affect eye movements.[72, 73]

Outpatient Care

Adjustment of hormonal therapy is necessary following transsphenoidal surgery (TSS), generally accomplished in the weeks following surgery by the consulting endocrinologist.

Long-term neuro-ophthalmologic surveillance is essential, especially when there is residual tumor close to the anterior visual pathway. A neuro-ophthalmologic examination including visual acuity, color vision, visual field testing, ocular motility, fundus photographs, and pRNFL and mGCIPL OCT should be performed before surgery and within 2–3 months after surgery to provide a baseline for future examinations. Subsequently, neuro-ophthalmologic surveillance should be performed at 3–12-month intervals or earlier if patients develop new visual symptoms.

Consultations

The treatment team should be multidisciplinary and ideally formed by a neuro-ophthalmologist, neuroradiologist, endocrinologist, neurosurgeon, neuropathologist, neuro-oncologist and radiation medicine specialist.

Different specialists may be involved as indicated by the patient's specific symptoms.

Medication Summary

All hormone-related therapy should be initiated and directed by a consulting endocrinologist. Management of specific disorders is as follows:

Prolactinomas - Dopamine agonists (eg, bromocriptine, cabergoline)

Acromegaly - Octreotide (somatostatin analogue), dopamine agonists

Hypothyroidism - Synthroid

Adrenocorticosteroid deficiency - Cortisol

Male hypogonadism - Testosterone

Female hypogonadism - Estrogen/progesterone

Growth hormone deficiency - GH replacement may be needed, more often in children than in adults

Many patients who have undergone surgery may experience posterior pituitary hypofunction with resultant diabetes insipidus and may require transnasal arginine vasopressin (DDAVP).

Octreotide (Sandostatin)

Clinical Context:  Hypothalamic polypeptide that inhibits production of GH. Acts primarily on somatostatin receptor subtypes II and V. Has multitude of other endocrine and nonendocrine effects, including inhibition of glucagon, VIP, and GI peptides. More effective than dopamine agonists in acromegaly.

Class Summary

These agents are somatostatin receptor ligands used to treat disorders associated with acromegaly. 

Bromocriptine (Parlodel)

Clinical Context:  Semisynthetic ergot alkaloid derivative; strong dopamine D2-receptor agonist; partial dopamine D1-receptor agonist. Inhibits prolactin secretion with no effect on other pituitary hormones.

Cabergoline

Clinical Context:  Semisynthetic ergot alkaloid derivative; strong dopamine D2-receptor agonist with low affinity for D1 receptors. Prolactin secretion by anterior pituitary predominates under hypothalamic inhibitory control exerted through dopamine.

 

Class Summary

Activate dopamine receptors on pituitary lactotrophs, reducing prolactin secretion. They can also inhibit other anterior pituitary cells, such as pituitary somatotrophs.

Hydrocortisone (Cortef, Solu-Cortef)

Clinical Context:  Glucocorticoid drug of choice because of its mineralocorticoid activity and glucocorticoid effects and its equivalency to the adrenal product (eg, cortisol). 

Class Summary

Used in the management of adrenocortical insufficiency.

Levothyroxine (Synthroid, Levoxyl, Euthyroid, Unithroid, Tirosint)

Clinical Context:  DOC. Rapidly inhibits the release of thyroid hormones via a direct effect on the thyroid gland and inhibits the synthesis of thyroid hormones. Iodide also appears to attenuate cAMP-mediated effects of thyrotropin. In active form, influences growth and maturation of tissues. Involved in normal growth, metabolism, and development.

Class Summary

These agents are used as supplemental therapy in hypothyroidism.

Estrogens (Premarin)

Clinical Context:  Contains a mixture of estrogens obtained exclusively from natural sources, occurring as the sodium salts of water-soluble estrogen sulfates blended to represent the average composition of material derived from pregnant mares' urine. Mixture of sodium estrone sulfate and sodium equilin sulfate. Contains as concomitant components, sodium sulfate conjugates, 17-alpha-dihydroequilenin, 17-alpha-estradiol, and 17-beta-dihydroequilenin.

Restores estrogen levels to concentrations that induce negative feedback at gonadotrophic regulatory centers, which, in turn, reduces release of gonadotropins from pituitary. Increases synthesis of DNA, RNA, and many proteins in target tissues.

Important in developing and maintaining female reproductive system and secondary sex characteristics; promotes growth and development of vagina, uterus, fallopian tubes, and breasts. Affects release of pituitary gonadotropins; causes capillary dilatation, fluid retention, and protein anabolism; increases water content of cervical mucus; and inhibits ovulation. Predominantly produced by the ovaries.

Class Summary

These agents are used in the treatment of hypoestrogenism.

Testosterone (Depo-Testosterone, Aveed, Testim)

Clinical Context:  Anabolic steroid that promotes and maintains secondary sex characteristics in androgen-deficient males.

Class Summary

These agents are used in the treatment of male hypogonadism.

Human growth hormone (Genotropin, Humatrope, Nutropin, Omnitrope)

Clinical Context:  Stimulates growth of linear bone, skeletal muscle, and organs. Stimulates erythropoietin, which increases red blood cell mass.

Currently widely available in SC injection form. Adjust dose gradually based on clinical and biochemical responses assessed at monthly intervals, including body weight, waist circumference, serum IGF-1, IGFBP-3, serum glucose, lipids, thyroid function, and whole body dual-energy x-ray absorptiometry. In children, assess response based on height and growth velocity. Continue treatment until final height or epiphysial closure or both occur.

Class Summary

These agents are used in the replacement of endogenous growth hormone in patients with adult growth hormone deficiency.

Desmopressin (DDAVP)

Clinical Context:  Synthetic analog of hypothalamic/posterior pituitary hormone 8-arginine vasopressin (antidiuretic hormone [ADH]). Has no effect on V1 receptors, which are responsible for vasopressin-induced vasoconstriction. Instead, acts on V2 receptors at renal tubule, increasing cellular permeability of collecting ducts, which are responsible for antidiuretic effect. Effect is prevention of nocturnal diuresis and elevated BP in the mornings, resulting in reabsorption of water by kidneys. Formulated as a tab and a nasal spray. Tab is more convenient to administer.

Class Summary

These agents are used in the treatment of diabetes insipidus.

Pegvisomant (Somavert)

Clinical Context:  GH-receptor antagonists have demonstrated effective suppression of GH and IGF-I levels in patients with acromegaly resulting from pituitary tumors or ectopic GHRH hypersecretion.

Class Summary

Analogs of human growth hormone selectively bind to growth hormone receptors and block the binding of endogenous GH, decreasing growth hormone effects.

Etomidate (Amidate)

Clinical Context:  Shown to depress adrenal cortical function. Inhibits enzymatic biosynthesis of steroid hormones.

Ketoconazole (Nizoral)

Clinical Context:  Imidazole broad-spectrum antifungal agent that acts on several P-450 enzymes, including the first step in cortisol synthesis, cholesterol side-chain cleavage, and conversion of 11-deoxycortisol to cortisol. It may inhibit ACTH secretion when used at therapeutic doses.

Levoketoconazole (Recorlev)

Clinical Context:  Inhibits key steps in the synthesis of cortisol and testosterone, including cholesterol side-chain cleavage, the first step in the conversion of cholesterol to pregnenolone for subsequent cortisol synthesis.  

Osilodrostat (Isturisa)

Clinical Context:  Inhibits 11 beta-hydroxylase, the enzyme responsible for the final step of cortisol synthesis in the adrenal gland. 

Metyrapone (Metopirone)

Clinical Context:  Inhibits 11 beta-hydroxylase, preventing conversion of 11 deoxycortisol to cortisol. 

Mitotane (Lysodren)

Clinical Context:  Decreases the production of cortisol by causing adrenal atrophy and affecting mitochondria in adrenocortical cells.

Class Summary

Effective and fast method to control hypercortisolism.

Mifepristone (Korlym)

Clinical Context:  At high doses blocks effect of cortisol at the glucocorticoid receptor, antagonizing the effects of cortisol.

Class Summary

These agents block peripheral glucocorticoid action. 

What are pituitary tumors?What is the pathophysiology of pituitary tumors?How are pituitary tumors classified?What are the clinical effects of growth hormonal deficiencies in pituitary tumors?What are clinical effects of gonadotrophin deficiency in pituitary tumors?What are clinical effects of thyrotropin deficiency in pituitary tumors?What are clinical effects of corticotrophin deficiency in pituitary tumors?What are clinical effects of panhypopituitarism in pituitary tumors?What are clinical effects of prolactin overproduction in pituitary tumors?What are clinical effects of growth hormone overproduction in pituitary tumors?What are clinical effects of Cushing disease in pituitary tumors?What is the prevalence of pituitary tumors in the US?What is the global prevalence of pituitary tumors?What is the mortality and morbidity associated with pituitary tumors?What is the sexual predilection of pituitary tumors?Which age groups have the highest prevalence of pituitary tumors?What are the signs and symptoms of pituitary tumors?Which physical findings are characteristic of pituitary tumors?Which neuro-ophthalmologic findings are characteristic of pituitary tumors?What are the ophthalmoscopic exam findings in patients with pituitary tumors?Which physical changes are associated with pituitary tumors?Which physical findings are characteristic of Cushing disease in patients with pituitary tumors?Which physical findings are characteristic of hypopituitarism in patients with pituitary tumors?How are pituitary tumors differentiated from other neoplasms?Which causes of hyperprolactinemia should be included in the differential diagnoses of pituitary tumors?What are the differential diagnoses for Pituitary Tumors?Which studies are performed to assess a pituitary mass in patients with pituitary tumors?Which studies are performed to assess prolactinomas in patients with pituitary tumors?Which studies are performed to assess growth hormone abnormalities in patients with pituitary tumors?How are Cushing disease and Cushing syndrome diagnosed in patients with pituitary tumors?How are glycoprotein hormones assessed in patients with pituitary tumors?What is the role of MRI in the workup of pituitary tumors?What is the role of CT scanning in the workup of pituitary tumors?What is the role of cerebral angiography in the workup of pituitary tumors?Which tests are performed in the workup of pituitary tumors to assess granulomas or infections?Which procedures may be helpful in the workup of pituitary tumors?What is the role of a pathologic exam in the diagnosis of pituitary tumors?How are pituitary tumors treated?What is the role of surgery in the treatment of pituitary tumors?What is the role of transsphenoidal surgery in the treatment of pituitary tumors?What is the surgical treatment for prolactinomas in patients with pituitary tumors?What is the surgical treatment for acromegaly in patients with pituitary tumors?What is the surgical treatment for Cushing disease in patients with pituitary tumors?Which specialist consultations are beneficial to patients with pituitary tumors?Which dietary modifications are used in the treatment of pituitary tumors?Which activity modifications are used in the treatment of pituitary tumors?What is the role of medications in the treatment of pituitary tumors?Which medications in the drug class Vasopressin Analogs are used in the treatment of Pituitary Tumors?Which medications in the drug class Growth Hormone are used in the treatment of Pituitary Tumors?Which medications in the drug class Androgens are used in the treatment of Pituitary Tumors?Which medications in the drug class Estrogen Derivatives are used in the treatment of Pituitary Tumors?Which medications in the drug class Thyroid Products are used in the treatment of Pituitary Tumors?Which medications in the drug class Corticosteroids are used in the treatment of Pituitary Tumors?Which medications in the drug class Dopamine Agonists are used in the treatment of Pituitary Tumors?Which medications in the drug class Somatostatin Analogs are used in the treatment of Pituitary Tumors?

Author

Jorge C Kattah, MD, Head, Associate Program Director, Professor, Department of Neurology, University of Illinois College of Medicine at Peoria

Disclosure: Nothing to disclose.

Coauthor(s)

Andrew J Tsung, MD, Assistant Professor of Neurosurgery, University of Illinois College of Medicine at Peoria; Director, INI Brain Tumor Center, Director of Neurosurgery Research, Department of Neurosurgery, Illinois Neurological Institute; Physician Director, Intermediate Neuroscience Care Unit, OSF St Francis Medical Center; Attending Physician, Illinois Neurological Institute Physicians, LLC

Disclosure: Nothing to disclose.

Fernando Labella Álvarez, MD, Degree of Medicine

Disclosure: Nothing to disclose.

Specialty Editors

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Nicholas Lorenzo, MD, CPE, MHCM, FAAPL, Co-Founder and Former Chief Publishing Officer, eMedicine and eMedicine Health, Founding Editor-in-Chief, eMedicine Neurology; Founder and Former Chairman and CEO, Pearlsreview; Founder and CEO/CMO, PHLT Consultants; Former Chief Medical Officer, MeMD Inc

Disclosure: Nothing to disclose.

Additional Contributors

Frederick M Vincent, Sr, MD, Clinical Professor, Department of Neurology and Ophthalmology, Michigan State University Colleges of Human and Osteopathic Medicine

Disclosure: Nothing to disclose.

Joseph V Hanovnikian, University of Illinois College of Medicine

Disclosure: Nothing to disclose.

Robert A Egan, MD, NW Neuro-Ophthalmology

Disclosure: Received honoraria from Biogen Idec and Genentech for participation on Advisory Boards.

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This is a characteristic bitemporal hemianopic visual field defect.

This contrast-enhanced coronal MRI was obtained in a patient who complained of visual loss.

This visual field was plotted using a Goldman perimeter (ie, kinetic perimetry). It was obtained from a patient who reported visual loss and had a normal endocrine workup. The dark areas correspond to the impaired peripheral visual field. This visual field defect is consistent with an intrasellar lesion.

Coronal T1 precontrast MRI A (left panel), B postcontrast (middle panel) and T2 (right panel) showing a sellar mass causing obvious left and upward displacement of the optic chiasm. The mass is a histologically proven pituitary macroadenoma, which presented initially with a large cystic subfrontal extension that was successfully resected in April of 2006. This patient has been observed closely for 2.5 years and despite obvious mass effect, he has no visual complaints and the neuro-ophthalmologic evaluation is normal. Although infrequent, clinicians should be aware of this possibility. Close follow-up is required.

Axial, sagittal, and coronal MRI of the sellae in a patient with a severe headache, normal neuro-ophthalmologic examination, and no evidence of endocrine failure. A hyperintense mass is observed in the sella with suprasellar extension. This case illustrates the clinical spectrum of pituitary apoplexy. Transsphenoidal resection confirmed the diagnosis of pituitary apoplexy.