Quiz: Pituitary Adenomas — 24 questions

1. Which description best defines a pituitary adenoma?

A. A malignant hypothalamic tumor classified by metastatic spread and hormone loss

B. An inflammatory sellar lesion classified by immune markers and visual symptoms

C. A vascular brain tumor classified by location and degree of hemorrhage

D. A benign pituitary-gland tumor classified by size and hormonal function

Answer: (D)

Explanation

A pituitary adenoma arises from the pituitary gland and is categorized according to its size and hormonal activity. The term benign does not guarantee that every tumor will be clinically harmless, which is why the other descriptions do not fit.

2. Why have pituitary adenomas also been called pituitary neuroendocrine tumors, or PitNETs, since 2017?

A. They arise from neural tissue rather than endocrine pituitary cells

B. The newer term identifies tumors that lack any hormonal activity

C. Most are malignant and commonly spread to distant organs

D. Some can behave aggressively and create significant oncological problems

Answer: (D)

Explanation

The term PitNET reflects the fact that some of these tumors can be aggressive and raise oncological concerns. It does not mean that most are malignant or that they lack endocrine characteristics.

3. What are the reported prevalence and annual incidence of pituitary adenomas?

A. A prevalence of 4 per 100,000 and an incidence of 78–94 per 100,000 per year

B. A prevalence of 10 per 100,000 and an incidence of 15–40 per 100,000 per year

C. A prevalence of 15–40 per 100,000 and an incidence of 10 per 100,000 per year

D. A prevalence of 78–94 per 100,000 and an incidence of 4 per 100,000 per year

Answer: (D)

Explanation

Pituitary adenomas have a prevalence of 78 to 94 per 100,000 inhabitants and an incidence of 4 per 100,000 inhabitants annually. Reversing prevalence and incidence produces the main misleading alternative.

4. A somatotroph adenoma contains an activating mutation affecting the alpha subunit of a G protein; which oncogene is associated with this abnormality?

A. The CDKN2A oncogene

B. The gsp oncogene

C. The PTTG oncogene

D. The AIP oncogene

Answer: (B)

Explanation

The gsp oncogene results from an activating mutation of the alpha subunit of G proteins and occurs in about 40% of somatotroph adenomas. AIP mutations are more closely associated with familial pituitary adenomas.

5. Which statement correctly describes germline AIP mutations in pituitary tumorigenesis?

A. They activate G proteins in approximately 40% of all pituitary adenomas

B. They produce clinically evident hormone hypersecretion in nonfunctional adenomas

C. They cause some familial adenomas but are not implicated in sporadic tumorigenesis

D. They cause most sporadic somatotroph adenomas but rarely affect familial tumors

Answer: (C)

Explanation

Germline AIP mutations account for some familial pituitary adenomas and do not appear to participate in sporadic tumor development. The gsp abnormality, rather than AIP mutation, is prominent in sporadic somatotroph adenomas.

6. What distinguishes a functional pituitary adenoma from a nonfunctional adenoma?

A. A functional adenoma invades bone, whereas a nonfunctional adenoma remains confined to the sella

B. A functional adenoma occurs in families, whereas a nonfunctional adenoma is usually sporadic

C. A functional adenoma secretes hormones, whereas a nonfunctional adenoma lacks clinically evident hormone hypersecretion

D. A functional adenoma is larger, whereas a nonfunctional adenoma is defined by microscopic size

Answer: (C)

Explanation

Functional adenomas produce hormones, while nonfunctional adenomas do not cause clinically evident hormone hypersecretion. Tumor size, inheritance, and bony invasion are separate features rather than the defining distinction.

7. A pituitary tumor measures 8 mm across on imaging; how should it be classified by size?

A. As a macroadenoma because it exceeds the usual microscopic threshold

B. As a microadenoma because it measures less than 10 mm

C. As a macroadenoma because any measurable tumor is considered large

D. As an indeterminate adenoma because size classification begins above 12 mm

Answer: (B)

Explanation

A microadenoma measures less than 10 mm, so an 8-mm lesion meets that definition. A macroadenoma is larger than 10 mm, not merely any measurable lesion.

8. Which Hardy stage describes a pituitary tumor extending laterally toward the cavernous sinus or retro-sellar region?

A. Stage A

B. Stage C

C. Stage D

D. Stage B

Answer: (C)

Explanation

Hardy stage D indicates lateral extension toward the cavernous sinus or extension behind the sella. Stage A is intrasellar, stage B extends toward the optic chiasm, and stage C extends into the sphenoid sinus.

9. In the Knosp classification, what does grade 4 indicate?

A. The tumor completely surrounds the internal carotid artery

B. The tumor remains amenable to complete surgical resection

C. The tumor has no invasion of the cavernous sinus

D. The tumor extends beyond the external carotid tangent

Answer: (A)

Explanation

Knosp grade 4 represents complete encasement of the internal carotid artery. Absence of cavernous invasion corresponds to grade 1, while extension beyond the external carotid tangent corresponds to grade 3.

10. Which grouping represents the WHO 2017 immunohistochemical families of pituitary adenomas?

A. Hardy, Knosp, and Trouillas

B. GH, ACTH, and prolactin

C. PIT1, Tpit, and SF1

D. Invasive, proliferative, and metastatic

Answer: (C)

Explanation

The WHO 2017 system groups adenomas into the PIT1, Tpit, and SF1 immunohistochemical families. Hardy and Knosp are radiological classifications rather than immunohistochemical families.

11. When pituitary hormone expression is weak, negative, or discordant, what is the principal value of immunohistochemistry?

A. It determines whether the tumor has metastasized

B. It measures the lesion's cavernous sinus invasion

C. It identifies the degree of chiasmal compression

D. It detects the tumor's hormonal content

Answer: (D)

Explanation

Immunohistochemistry can reveal pituitary hormonal content, including prolactin, TSH, GH, ACTH, FSH, LH, and the alpha subunit, even when expression is unclear. Cavernous sinus invasion and chiasmal compression are anatomical or radiological findings, not the primary information provided by this testing.

12. A pituitary adenoma is invasive but nonproliferative; which Trouillas grade best describes it?

A. Grade 2a

B. Grade 2b

C. Grade 1a

D. Grade 1b

Answer: (A)

Explanation

Trouillas grade 2a denotes an invasive but nonproliferative adenoma. Grade 1a is noninvasive and nonproliferative, while grade 1b is noninvasive but proliferative and grade 2b is both invasive and proliferative.

13. A large pituitary lesion causes visual-field defects but no ocular motor nerve palsy; which mechanism most directly explains the visual-field loss?

A. Disconnection of the pituitary stalk

B. Compression of the visual pathways

C. Involvement of the cavernous sinus

D. Autonomous secretion of pituitary hormone

Answer: (B)

Explanation

Visual-field defects result from compression of the visual pathways by the lesion. Ocular motor nerve palsy instead suggests cavernous sinus involvement, whereas stalk disconnection and hormone secretion do not directly produce this visual pattern.

14. Which presentation most strongly indicates pituitary apoplexy rather than a gradually developing tumor syndrome?

A. Sudden severe headache with acute visual disturbance

B. Gradual reduction in visual acuity from lesion enlargement

C. Progressive visual-field loss with mild recurring headache

D. Chronic ocular motor deficits without an abrupt change

Answer: (A)

Explanation

Pituitary apoplexy presents abruptly, classically with severe headache and acute visual disturbance caused by chiasmal compression. Progressive visual or ocular symptoms without sudden onset are more consistent with an evolving tumor syndrome.

15. How does pituitary stalk disconnection cause hyperprolactinemia?

A. It removes hypothalamic inhibition of prolactin release

B. It causes autonomous prolactin secretion by the adenoma

C. It increases prolactin production during renal failure

D. It stimulates prolactin release through thyroid hormone excess

Answer: (A)

Explanation

Stalk disconnection interrupts hypothalamic dopamine delivery, thereby removing inhibition of prolactin secretion. Autonomous secretion is the mechanism of a prolactinoma, not stalk disconnection.

16. Which manifestation is specifically a menstrual disturbance associated with hyperprolactinemia in women?

A. Amenorrhea

B. Reduced libido

C. Dyspareunia

D. Galactorrhea

Answer: (A)

Explanation

Amenorrhea is the menstrual disturbance associated with hyperprolactinemia and occurs in about 90% of affected cases. Galactorrhea refers to milk secretion, while dyspareunia and reduced libido are other possible consequences.

17. What is the first-line treatment for a prolactinoma?

A. A dopamine agonist such as cabergoline

B. Emergency radiotherapy for hormone suppression

C. Transsphenoidal surgery in every patient

D. A somatostatin analogue as initial therapy

Answer: (A)

Explanation

Dopamine agonists, including cabergoline, bromocriptine, and quinagolide, are first-line treatment for prolactinomas. Surgery is generally reserved for selected cases such as intolerance or ineffective medical treatment, rather than being the routine initial approach.

18. Which finding best distinguishes adult acromegaly from childhood growth-hormone excess?

A. Reduced soft-tissue growth with normal facial features

B. Rapid height increase before epiphyseal closure

C. Generalized short stature with delayed skeletal maturation

D. Acquired enlargement of extremities after epiphyseal closure

Answer: (D)

Explanation

Acromegaly develops in adults after epiphyseal closure and produces enlargement of the extremities and characteristic soft-tissue changes. Childhood growth-hormone excess instead causes gigantism, primarily through excessive linear growth.

19. Which oral glucose tolerance test result supports a diagnosis of acromegaly?

A. Growth hormone nadir greater than $0.1\ \text{µg/L}$

B. Growth hormone nadir below $0.1\ \text{µg/L}$

C. Growth hormone peak below $1\ \text{IU/L}$

D. Growth hormone level that normalizes after fasting

Answer: (A)

Explanation

A growth hormone nadir greater than $0.1\ \text{µg/L}$, equivalent to $1\ \text{IU/L}$, supports acromegaly after oral glucose administration. A suppressed nadir below this threshold would argue against the diagnosis.

20. What is the usual treatment sequence for a somatotroph adenoma when surgery is feasible?

A. Observation first, followed by surgery after symptoms progress

B. Surgical treatment, followed by radiotherapy if surgery fails

C. Medical therapy first, followed by radiotherapy in every case

D. Radiotherapy first, followed by surgery for residual disease

Answer: (B)

Explanation

Somatotroph adenomas are often treated surgically, with radiotherapy considered after surgical failure and medical therapy used when those approaches are contraindicated or before surgery for invasive tumors. Routine radiotherapy or observation as the initial approach does not reflect the stated sequence.

21. Which clinical pattern is most consistent with a corticotroph adenoma?

A. Polyuria, hypernatremia, visual loss, and severe thirst

B. Proximal muscle wasting, thin bruisable skin, and wide purple striae

C. Pallor, fatigue, weight loss, and generalized hormone deficiency

D. Cold intolerance, dry skin, bradycardia, and weight gain

Answer: (B)

Explanation

Corticotroph adenoma causes cortisol excess, producing proximal and abdominal muscle wasting, thin bruisable skin, and wide purple striae, along with metabolic and cardiovascular effects. The last pattern reflects pituitary hormone deficiency rather than cortisol excess.

22. Which hormonal testing pattern is characteristic of a corticotroph adenoma?

A. Elevated cortisol, failed low-dose suppression, and high-dose ACTH suppression

B. Low cortisol, successful low-dose suppression, and high-dose ACTH elevation

C. Normal cortisol rhythm, failed high-dose suppression, and reduced ACTH

D. Elevated cortisol, successful low-dose suppression, and absent ACTH secretion

Answer: (A)

Explanation

Corticotroph adenoma produces elevated cortisol with loss of its circadian rhythm; low-dose suppression tests fail, while ACTH is elevated but suppressible with high-dose testing. Successful low-dose suppression would not fit autonomous cortisol excess from a corticotroph adenoma.

23. Why should anterior pituitary insufficiency be assessed in every patient with a pituitary adenoma?

A. Pituitary adenomas invariably cause complete hormone excess

B. Anterior pituitary function remains unaffected by tumor growth

C. Hormonal deficits occur only when the tumor secretes cortisol

D. Each pituitary hormone axis may show clinical deficiency

Answer: (D)

Explanation

A pituitary adenoma can impair multiple anterior pituitary axes, so patients should be evaluated for signs of deficiency across each axis. Hormonal abnormalities are not limited to cortisol-secreting tumors, and adenomas do not invariably produce complete hormone excess.

24. Which statement correctly describes pituitary MRI and delayed recognition of acromegaly?

A. MRI has limited value, and diagnosis is typically delayed a few weeks

B. CT is the reference test, and diagnosis usually occurs within one year

C. Plain radiography is preferred, and diagnosis follows immediately after symptoms begin

D. MRI is the reference test, and diagnosis may be delayed 4 to 10 years

Answer: (D)

Explanation

MRI is the reference examination for detecting pituitary microadenomas and macroadenomas, while clinical recognition of acromegaly may be delayed for 4 to 10 years. CT and plain radiography are not the stated reference methods for this purpose.