Ch. 9 - Pituitary Tumors Flashcards Preview

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Flashcards in Ch. 9 - Pituitary Tumors Deck (54)
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Incidence of pituitary tumors

8-10% of all intracranial tumors

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Pituitary adenoma origin

From anterior lobe (adenohypophysis)

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Microadenoma vs. macroadenoma

Micro: < 10mm

Macro: >10mm

3

Pituitary adenoma spread and consequences

Local invasion inferiorly through floor of sella (CSF rhinorrhea)

Superiorly to suprasellar cisterns (compression of optic chiasm, hypothalamus, 3rd ventricle)

Laterally to cavernous sinus (CN disturbance)

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Lateral microadenomas are more likely to produce which hormones?

Prolactin and GH

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Central microadenomas are more likely to produce which hormone?

ACTH

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Effects of prolactin

Breast growth and promotion of lactation; important in spermatogenesis

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How is prolactin secretion regulated?

Dopamine blocks prolactin secretion (UNLIKE ALL OTHER PITUITARY HORMONES)

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Characteristic presentation of prolactinomas

Young females with amenorrhea and galactorrhea; males with impotence

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Prolactin level suggestive of pituitary adenoma

>2000 ng/mL (nl 70-550)

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Other pituitary adenomas associated with hyperprolactinemia

GH and null cell can cause hyperprolactinemia 2/2 mass effect blocking DA secretion

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Consequences of ACTH adenoma

ACTH stimulates adrenal cortex to secrete cortisol = CUSHING'S DISEASE

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Null cell adenoma histology

Chromophobic (no cytoplasmic granules) + accumulation of mitochondria (then called 'oncocytomas')

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Null cell adenoma presentation

Aggressive and grow quickly = visual disturbances

Hormonally silent

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Factors affecting presentation of pituitary adenomas

Size of tumor + endocrine fxn of secreted hormones

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Visual field deficits a/w pituitary adenoma

Compression of optic chiasm -> bitemporal hemianopsia

Compression of optic tract -> homonymous hemianopsia

Compression of posterior chiasm -> bilateral central scotomas

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Extraocular deficits a/w pituitary adenomas

CN3, 4, 6 palsies

CN5 damage 2/2 cavernous sinus invasion causes facial pain

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Sxs of hypopituitarism

Pre-pubertal: retards development of 2ndary sex characteristics

Post-pubertal: fatigue, muscle weakness, anorexia --> episodic confusion/drowsiness (severe) can be precipitated by stressful events

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Sxs of pituitary apoplexy

Spontaneous hemorrhage into pituitary tumor = sudden severe HA, transient LOC + extraocular muscle paralysis (looks like SAH + EOM involvement)

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What do GH-secreting tumors cause?

Kids - gigantism

Adults (30-40) - acromegaly (enlarged hands/feet, coarse/greasy skin, sweat profusely, HTN, cardiac hypertrophy, diabetes)

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Cushing's disease

ACTH-producing pituitary adenoma (80% microadenomas)

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Cushing's disease mortality

50% at 5 years

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Cushing's disease sxs

Obesity, thin skin, striae, fat redistribution (moon face, buffalo hump), easy bruising, acne, facial hair, weakness/muscle atrophy, osteoporosis, glucose intolerance

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Causes of Cushing's syndrome

90% of cases 2/2 Cushing's disease (ACTH-producing pituitary adenoma)

OTHER: adrenal adenoma/carcinoma or ectopic ACTH (small cell lung CA)

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Nelson-Salassa syndrome

ACTH-producing pituitary adenoma in pt w/ bilateral adrenalectomy -> no negative feedback -> accelerated growth of existing adenoma (usually macroadenoma)

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Cutaneous findings of Nelson-Salassa syndrome

Hyperpigmentation 2/2 beta-MSH production (ACTH breakdown product)

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How is GH-secreting tumor diagnosed?

Glucose suppression test - measure GH following glucose bolus (should suppress normally)

IGF-1 levels - indicator of GH activity

Other: measure GHRH or TRH

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How is Cushing's disease diagnosed?

1. Hypercortisolemia on 24 hr urine cortisol

2. Dexamethasone suppression test (high-dose will suppress pituitary adenoma but NOT ectopic or adrenal ACTH source)

3. Administer CRH and measure differential ACTH level in periphery/pertrosal sinus

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Scan of choice for pituitary adenomas?

High resolution CT/MRI with contrast

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Appearance of pituitary micro vs. macroadenoma on CT?

Micro: hypodense, upward bulging, deviation of pituitary stalk, thinning of sella

Macro: contrast-enhancing lesion in sella, best seen on coronal section