Ch. 9 - Pituitary Tumors Flashcards by Franz Biehl

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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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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Microadenoma vs. macroadenoma

Micro: < 10mm

Macro: >10mm

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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

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

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)

Nelson-Salassa syndrome

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

Cutaneous findings of Nelson-Salassa syndrome

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

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

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

Scan of choice for pituitary adenomas?

High resolution CT/MRI with contrast

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

Appearance of pituitary micro vs. macroadenoma on MRI?

Micro: T1 - hypointense T2 - hyperintense Macro: T1 - isointense T2 - hyperintense

Ddx of pituitary adenoma

Craniopharyngioma (pituitary gland embryonic tissue) OR suprasellar meningioma (part of sella turcica) Uncommon: optic nerve/hypothalamus glioma, aneurysm, Rathke's cleft cysts

Indications for surgical excision of pituitary adenomas

1. Large tumors compressing adjacent structures (esp. visual pathways) 2. GH-secreting (causing acromegaly) 3. ACTH secreting (causing Cushing's) 4. Refractory prolactinomas

Surgical approaches to pituitary adenomas

Transphenoidal vs. transcranial excision

Post-operative management of pituitary excision

Fluid balance and hormonal status! Endocrine deficiency replacement with (1) parenteral hydrocortisone and (2) vasopressin for transient DI

Indications for postoperative radiotherapy in pituitary adenomas

Subtotal excision or residual hormone secretion

Medical tx of micro prolactinomas

Bromocriptine = dopamine agonist; significant side effects (n/v, postural hypotension)

Craniopharyngioma origin

Epithelial remnants of Rathke's pouch

Craniopharyngioma histology

Cystic tumor with yellow fluid (cholesterol crystals) 1. Adamantinous - all children have this type 2. Papillary - 1/3 of adults, rare in children

Craniopharyngioma presentation

1. Elevated ICP (3rd ventricular obstruction) - HA, vomiting, papilledema 2. Visual impairment - papilledema vs. chiasmal compression (direct) 3. Endocrine abnormalities - hypogonadism, stunted growth, DI

Craniopharyngioma appearance on CT

Cystic tumor in suprasellar region with curvilinear calcification

DDx of craniopharyngioma

Rathke's cleft cyst

Craniopharyngioma tx

Pterional craniotomy vs. bifrontal craniotomy (top-down approach since tumor is suprasellar)

Empty sella syndrome

Communicating extension of subarachnoid space into pituitary fossa 2/2 defect in diaphragma sella OR pituitary surgery/radiotherapy OR increased ICP = herniation of subarachnoid space Considered ANATOMICAL VARIANT

Classic pt with empty sella syndrome

Obese, hypertensive, middle-age woman

Sxs of empty sella syndrome

HA, spontaneous CSF rhinorrhea

Tx of empty sella syndrome with CSF rhinorrhea

Repair leak in floor of sella with crushed muscle and fascia lata + CSF shunt

Anterior pituitary lobe vs. posterior lobe development

Anterior lobe - Rathke's pouch Posterior lobe - infundibulum (floor of diencephalon)

Hormones released by anterior pituitary? Posterior pituitary?

Anterior - GH, TSH, ACTH, prolactin, LH, FSH Posterior - ADH, oxytocin

What is the most common pituitary adenoma?

Prolactinoma (40%) \> GH adenoma (20%) = non-secreting adenoma (20%) \> ACTH adenoma (15%)