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2: pituitary adenoma > Lecture: Pituitary pathology > Flashcards

Lecture: Pituitary pathology Flashcards

1
Q

Where is the pituitary gland located?

A

sella turnica in the sphenoid bone

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2
Q

What part of the pituitary has a direct connection with the hypothalamus?

A

The posterior pituitary

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3
Q

Describe the arterial supply to the anterior pituitary.

A

It does not have one, only portal venous drainage.

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4
Q

percentage of pituitary that is the anterior pituitary?

A

makes up about 80% of the gland

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5
Q

What is the embryological origin of the anterior pituitary?

A

Derived embryologically from Rathke’s pouch.

Eventually cut-off from its origin by the growth of the sphenoid bone.

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6
Q

Describe blood supply to anterior pituitary.

A

A portal vascular system – carries hypothalamic releasing hormones from the hypothalamus to
the pituitary gland.

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7
Q

What part of the pituitary produces oxytocin and ADH?

A

Posterior pituitary

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8
Q

Describe the structure of the posterior pituitary

A

Composed of modified glial cells known as pituicytes. Additionally axonal processes extending from nerve cell bodies in the hypothalamus, through the pituitary stalk to the posterior lobe these neurons produce ADH and oxytocin – stored in axon terminals in the posterior pituitary and are released into the circulation in response to appropriate stimuli

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9
Q

Causes of hypopituitarism?

A

ischaemia; surgery; radiation; inflammation; compression by nonfunctional adenomas.

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10
Q

Name six types of pituitary tumours

A
  • Pituitary adenoma
  • Pituitary carcinoma
  • Gangliocytoma
  • Mesenchymal tumours
  • Granular cell tumours
  • Secondary tumours
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11
Q

Most common cause of hyperpituitarism?

A

Pituitary adenoma

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12
Q 
What can 
– pituitary hyperplasia
– carcinomas of the anterior pituitary
– secretion of hormones by extra-pituitary tumours
– certain hypothalamic disorders
all cause?
A

Hyperpituitarism

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13
Q

Most common age demographic for pituitary adenomas?

A

Adults 30 - 50 years

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14
Q

What percentage of pituitary adenomas are associated with MEN1 mutations

A 
• 3% of adenomas are associated with MEN1
• germline mutation of MEN1 on chr 11q13
• autosomal dominant inheritance
– pancreas
• 50% G cell tumours
• 30% beta cell tumours
• 12% VIP cell tumours
– parathyroid
• chief cell hyperplasia
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15
Q

When is a pituitary adenoma defined as a macroadenoma rather than a microadenoma?

A

Greater than 1 cm

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16
Q

Name three locations in which ectopic pituitary adenomas can form.

A

– diencephalic infundibulum
– the pituitary stalk
– sphenoid bone between the nasopharynx and the pituitary fossa

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17
Q

Gross histological features of pituitary adenoma?

A

relatively uniform, polygonal cells are arranged in sheets or cords

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18
Q

Pituitary adenoma supportive connective tissue/reticulin histological features?

A

Sparse.

19
Q

Describe mitotic activity in pituitary adenomas

A

modest

20
Q

Describe pituitary adenoma nuclei characteristics?

A

nuclei uniform or pleomorphic

21
Q

Somatotrophs produce?

A

growth hormone

22
Q

Lactotrophs/ mammotrophs produce?

A

prolactin

23
Q

Corticotrophs produce?

A

ACTH

24
Q

Thyrotrophs produce?

A

TSH

25
Q

Gonadotrophs produce?

A

LH and FSH

26
Q

most frequent type of hyperfunctioning

pituitary adenoma

A

prolactinomas (lactotroph adenomas)

27
Q

Typical presentation of women of child bearing age with a prolactinomas?

A

galactorrhoea and aamenorrhoea

28
Q

Describe features of a weakly acidophilic or chromophobic prolactinoma?

A
  • sparsely granulated prolactinoma
  • PAS positive
  • diffuse or less commonly a papillary pattern
  • ± hyalinised stroma
  • microcalcification in about 20%
  • endocrine amyloid not uncommon
29
Q

Describe features of a strongly acidophilic prolactinoma?

A

densely granulated prolactinomas

– rare variant

30
Q

Describe six situations where hyperprolactinaemia can occur.

A
  • physiologic hyperprolactinaemia in pregnancy
  • lactotroph hyperplasia such as when there is
    interference with normal dopamine inhibition of prolactin: – post head injury – section of the pituitary stalk – drugs
    • the stalk effect – any mass in the suprasellar compartment may disturb the normal inhibitory influence of the hypothalamus on prolactin secretion.
    • drugs such as dopamine receptor agonists (haloperidol), reserpine
    • oestrogens; renal failure; hypothyroidism
31
Q

Second most common type of pituitary adenoma?

A

Growth hormone adenoma (somatroph adenoma)

32
Q

Clinical signs of a growth hormone adenoma?

A 
Acromegaly: A-B-C-D-E-F-G-H-I-J 
A Arthropathy B Big boggy hands 
C Carpal tunnel syndrome D Diabetes 
E Enlarged tongue, heart and throat 
F Fields (bitemporal hemianopia) 
G Gynaecomastia, Galactorrhoea and Greasy skin 
H Hypertension 
I Increasing size (of shoes, hat, gloves, dentures, rings)
J Jaw enlargement and prognathism..
33
Q

What type of GH adenoma is:
– slow growing, well differentiated tumour
– typically arises in older patients

A

densely granulated GH cell adenoma

34
Q 
What type of GH adenoma is:
– larger at presentation
– presents in younger patients
– more aggressive
– greater likelihood to be invasive and to recur
A

sparsely granulated tumour

35
Q

What type of pituitary adenoma commonly has perinuclear filaments?

A

perinuclear filaments are usually present and are an important diagnostic feature of ACTH producing neoplasms
– in extreme cases almost the entire cytoplasm is occupied by Crooke’s hyaline
– dependent on sustained hypercortisolism and corticoid treatment
• usually monohormonal

36
Q

Define pituitary apoplexy

A 
• sudden haemorrhage into the gland
• sudden onset of severe headache; diplopia and
hypopituitarism
• in severe cases
– cardiovascular collapse
– loss of consciousness
– sudden death
37
Q

What type of pituitary tumour is responsible for cushings disease?

A

Corticotroph cell adenoma.
Other causes:
• hypothalamic dysregulation
• possibly ectopic ACTH production (such as small cell lung tumour)

38
Q

how common are pituitary carcinomas?

A

rare

39
Q

How are pituitary carcinomas diagnosed?

A
  • diagnosis requires the demonstration of metastases
  • non functioning as well as secretory
  • transformation of pre-existing benign tumour as well as de novo malignant tumours
  • poor correlation between histology and behaviour
40
Q

Common sites of metastasis of pituitary adenoma?

A

not rare
• metastasis is more common in the neurophypohysis, leading to DI
• most common primary lesions
– breast
– lung
– GIT
- melanoma especially in australia
• occasionally the primary lesion remains occult
• most pituitary metastases are asymptomatic and constitute
incidental findings at autopsy in patients with disseminated
malignancy
• cases have been described where it has been the presenting
symptom
• metastasis to an adenoma has also been described

41
Q

Basic overview of Ischaemic necrosis and Sheehan syndrome

A

• during pregnancy the anterior pituitary enlarges to almost twice its normal size
• not accompanied by an increase in blood supply from the low pressure venous
system → relative ischaemia
• further reduction in BP may precipitate infarction
• less common causes
– DIC
– sickle cell anaemia
– raised ICP
– traumatic injury
– shock of any origin

42
Q

Where do crangiopharyngiomas derive from?

A

derived from vestigial remnants of Rathke’s pouch
• slow growing
• 1-5% of intracranial tumours
• a small number will arise within the sella but most are suprasellar ± intrasellar extension
– ventral or dorsal to the optic chiasm or in rare cases within the chiasm itself
– occasional cases have been described within the third ventricle
• can be implanted into other parts of the brain by repeated needle aspiration

43
Q

Describe age distribution of crangiopharyngiomas.

A

– bimodal age distribution
• children 5-15 presenting with growth retardation, hydrocephalus
• adults > 50 presenting with visual disturbances
– hypopituitarism and DI are common

44
Q

What lesion has the typical features of:
– 3 to 4 cm diameter
– encapsulated/ solid but more commonly cystic and sometimes multiloculated
– cysts contain ‘machine oil’ – a viscous fluid sparkling with cholesterol crystals
– focal calcification almost invariable – detectable by X-ray in about 75% of cases

A

crangiopharyngiomas

2: pituitary adenoma (6 decks)

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