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Flashcards in pituitary pathology Deck (60):
1

Function of T-pit

Trxn factor which promotes differentiation of rathe pouch stem cells into corticotrophs which will secrete ACTH. Also involved in ACTH secreting pituitary adenoma.

2

Function of Pit-1

Trxn factor which promotes differentiation of Rathke pouch stem cells into somatotroph stem cells. Can also be involved in mixed GH/TSH secreting adenomas

3

What do somatotroph stem cells differentiate into

1. Somatotrophs (secrete GH). 2. Thyrotrophs (secrete TSH)- can also convert back into somatotroph stem cells. 3. mammosomatotroph- further differentiates into somatotroph (GH) or latotroph (PRL)

4

distribution of cell types in anterior pituitary

Corticotrophs (ACTH) and thyrotrophs (TSH) in middle. Lactotrophs (PRL) and somatotrophs (GH) towards the sides

5

Staining of somatotrophs

Acidophilic (orangish) on PAS-orange G staining

6

normal anterior vs posterior pituitary histology

anterior: glandular with acidophilic, basophilic and chromophobic staining cells. Posterior: eosinophilic, fibrillar appearance with occasional swollen axonal processes (herring bodies)

7

Infundibulum histology

Congested, thin walled closely juxtaposed hypothalamic-hypophyseal portal system

8

Causes of pituitary adenomas

<5% are familial, the rest are sporadic with an unknown cause.

9

Genes associated with familial pituitary tumor syndromes

MEN1, CDKN1B, PRKAR1A and AIP (GH secreting adenomas)

10

Features suggesting an inherited pituitary tumor syndrome

parathyroid tumors, pancreatic endocrine tumors, atrial myxomas, lentigines, Schwann-cell tumors (Carney complex), family history and young age at onset

11

Pituitary tumor clinical presentation

1. hormone hypersecretion: acromegaly, Cushings, amenorrhea/galactorrhea. 2. Sx from mass effect: headaches, vision loss, piuitary gland dysfunction

12

pituitary adenoma grade

Almost all are WHO grade 1

13

Microadenoma vs macroadenoma of anterior pituitary

Micro: 10mm, distorts adjacent tissues such as the dura of the sellar floor or diaphragma sella causing headaches

14

pituitary adenomas and diabetes insipidus

DI is quite uncommon with pituitary adenomas of any size

15

Macroadenomas most common growth patterns

Most commonly grows directly upwards, compressing the optic chiasm and resulting in bitemporal hemianopsia (loss of lateral visual fields due to compression of medial retinal fields).

16

Less common growth patterns of macroadenomas of pituitary

1. compression of hypothalamus- hypothalamic dysfunction is rare. 2. Lateral growth outside the sella may compress the medial temporal lobe causing seizures. 3. May compress brain parenchyma but lack ability to infiltrate into brain parenchyma as single cells. 4. May extend laterally and compress the wall of the cavernous sinus, enwrapping the carotid artery (but not compromising) and distorting cranial nerves III, IV, and VI (cranial nerve palsies). 5. May extend into sphenoid sinus

17

Giant adenomas

Invasive adenomas >4cm

18

Imaging of macroadenomas and giant adenomas

Often show cysts and hemosiderin pigment in neuroimaging or in tumor specimen

19

Which pituitary tumors are responsive to medical therapy

Prolactinomas and GH secreting tumors (after surgical debulking)

20

Piuitary adenoma histology

intraoperative touch preparation shows abundant exfoliation of cytologically monotonous cells. Nuclear pleomorphism is uncommon. Mitoses are rare in microadenomas but occasionally seen in macro.

21

Histochemical stain for adenomas

Reticulin- normal pituitary has a nested pattern whereas adenoma has a disrupted reticulin pattern

22

Most frequency pituitary adenomas found incidentally at autopsy

prolactinoma, followed by null cell/gonadotroph

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clinical signs of prolactinoma

galactorrhea, amenorrhea, infertility, hypogonadism

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prolactinoma histology and immunoreactivity

Diffuse growth pattern, monotonous cell population with increased nuclear chromatin content and conspicuous vasculature. Diffuse immunoreactivity for PRL only.

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How does the size of a prolactinoma correlate with PRl levels

In premenopausal women, size of adenoma parallels serum levels closely. NOT true for men or post menopausal women.

26

Treatment of prolactinomas

Medical management with dopamine agonist usually prevents the need for surgery. Surgery is used when pts have low tolerance for meds, tumor doesn’t shrink appropriately with meds, or limited preoperative testing available

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Histology of prolactinoma after treatment with dopamine agonist

If recent and long term treatment, severe cytoplasmic shrinkage with near-naked nuclei that should not be mistaken for lymphocytes. Also often shows fibrosis

28

Clinical signs of gonadotroph cell adenoma/non secretor

headaches, visual field defects, cranial nerve palsies (ptosis, diplopia), pituitary hormone deficits, and rarely-seizzures, stroke or CSF leak.Also hypogonadism or clinically silent

29

gonadotroph cell adenoma histology

Sheet like architecture, perivascular arrangement of tumor cells, clear cell appearance, can have regions with more abundant oncocytic cytoplasm and regions with more scant cytoplasm.

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gonadotroph cell adenoma immunohistochem

Immunoreactivity with alpha subunit and FSH/LH. Patchy distribution

31

Growth and treatment of non-secretory adenomas including gonadotroph adenomas

Slow growing- usually don’t require post operative radiotherapy

32

clinical signs of GH secretion tumor

acromegaly- acral enlargement, soft tissu swelling, cardiac hypertrophy, HTN, hyperglycemia, sleep apnea

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clinical signs of TSH-cell adenoma

thyroid goiter, hyperthyroxinemia

34

Clinical signs of corticotroph adenoma

Cushings- hypercortisolism, central obesity, striae, hyperglycemia, osteroporosis, hirsutism

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histology of ACTH adenoma

densely granulated ACTH cells growing as sheets of monotonous round cells. Immunoreactivity with ACTH only

36

How do serum levels of ACTH correlate with size of corticotroph cell adenoma

They do not correlate at all! A small adenoma may cause profound cushings

37

What is ACTH hyperplasia and how is it diagnosed

An uncommon cause of pituitary ACTH excess. Diagnosed by histology showing expansion, rather than destruction, of acini by reticulin stain. Will show larger acini containing relatively homogenous populations of ACTH reactive cells. Look for ectopic source of CRF

38

what is pituitary apoplexy

Sudden headache, acute visual changes, ophthalmoplegia (Acute visual loss or inability to move eyes) and altered mental status (confusion) caused by the sudden hemorrhage or infarction of the pituitary gland

39

What cuases pituitary apoplexy

Occurs in 10-15% of pituitary adenomas, but of varying degree of severity.Not clearly cell type or size dependent. 65% occur in patients with undiagnosed pituitary tumors. Anterior pituitary dysfunction is common.

40

Pituitary apoplexy treatment

ICU care, steroids, surgery sometimes

41

pituitary apoplexy histology

necrosis with areas of discernible adenoma

42

Histology of Rathke cleft cyst

Ciliated columnar cyst lining, abundant amorphous eosinophilic nucin cyst contents in which are embedded small strips of pseudostratified ciliated columnar epithelium. Also squamous metaplasia (associated with cyst recurrence)

43

What is lymphocytic hypophysitis

Inflammatory process involving the pituitary (usually anterior but posterior can be involved). Primary hypophysitis is an autoimmune disorder involving classically affecting young women during late pregnancy or in the early postpartum period. Secondary type is caused by other factors

44

Lymphocytic hyophysitis histology

sheets of cytologically bland pure lymphocytic infiltrates

45

testing for lymphocytic hypophysitis

anti-pituitary autoantibodies is not reliable test.

46

Primary lymphocytic hypophysitis presentation, diagnosis, treatment

Usually presents as a mass lesion of the pituitary gland simulating pituitary adenoma on neuroimaging studies. Diagnosis: histological. Treatment: corticosteroids usually the only treatment needed. Sometimes surgery

47

Causes of secondary lymphocytic hypophysitis

TB, sarcoidosis, Wegeners granulomatosis, Sjogren syndrome, Langerhands cell histiocytosis, germ cell tumors, lymphoma, and rarely- pituitary adenoma, craniopharyngioma, or rathke cleft cysts with secondary tissue damage

48

Craniopharyngioma gross anatomy

Cystic and solid components.

49

craniopharyngioma histology

ghost cells

50

What is a hypothalamic hamartoma

Mass of neurons and glial cells. NOT a true neoplasm. fully differentiated neuroglial tissue that closely resembles normal hypothalamus but is jumbled

51

hypothalamic hamartoma presentation

Clinical manifestations, if any, are those of endocrine hyperfunction due to overproduction of hypothalamic gonadotropin-releasing hormone that can cause precocious puberty. Also can see convulsive laughter known as gelastic seizures

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hypothalamic hamartoma treatment

surigcal resection alone IF symptomatic

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most common sellar region mass

pituitary adenoma

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Who usually gets pituitary adenomas

young to middle age adults

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Who usually gets crainpharyngiomas

children and adults- often calcified

56

GH tumors recurrence

sparsely granulated GH tumors are more aggressive and have increased recurrence

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complications of GH tumors

mortality (increases with increasing levels of GH), DI, CSF leak, meningitis.

58

GH cell adenoma histology

monotonous cells, slightly pleomorphic medium sized cells often wth angular profile. Densely granulated with diffuse, strong staining for GH and keratin reactivity. OR sparsely granulated with cells that lack acidophilia and may show more eccentrically place nuclei and perinuclear clearing in cytoplasm.

59

Feature of sparsely granulated GH adenomas

often invade bone- will see entrapped bony spicules surrounded by tumor

60

GH cell adenoma treatment

Somatostatin analog, radiotherapy- convential, stereotactic (less radiation to surrounding structures), and lmited experience wit gamma knife, LINAC and proton beam