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ACEM Primary Written > Endocrinology: Pathology - Pituitary adenoma > Flashcards

Endocrinology: Pathology - Pituitary adenoma Flashcards

1
Q

Pituitary microadenoma

A

<1cm diameter

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2
Q

Pituitary macroadenoma

A

> 1cm diameter

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3
Q

Most common pituitary adenoma

A

Lactotroph adenoma (~30%)

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4
Q

Hormones produced by lactotroph adenoma

A

Prolactin

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5
Q

Hormones produced by somatotroph adenoma

A

GH

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6
Q

Hormones produced by corticotroph adenoma

A

ACTH

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7
Q

Hormones produced by gonadotroph adenoma

A

FSH, LH

Most are hormonally silent

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8
Q

Hormones produced by thyrotroph adenoma

A

TSH

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9
Q

Least common adenoma

A

Thyrotroph adenoma (<1%)

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10
Q

Hormones produced by plurihormonal adenoma

A

GH, PRL, TSH

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11
Q

Peak incidence of pituitary adenoma

A

35-60 years

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12
Q

Prevalence of pituitary adenoma

A

~14%

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13
Q

Macroscopic characteristics of pituitary adenoma

A

Typically soft/gelatinous and well-circumscribed
Up to 30% are aggressive adenomas (unencapsulated and infiltrate surrounding tissues e.g. cavernous and sphenoid sinuses, dura, occasionally brain itself)

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14
Q

Microscopic characteristics of pituitary adenoma

A

Cellular monomorphism

Sparse reticulin

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15
Q

Clinical features of non-functional pituitary adenoma

A

Present with symptoms related to mass effect:

  1. Radiographic abnormalities of sella turcica
  2. Visual field defects (classically bitemporal hemianopia)
  3. Signs and symptoms of raised ICP (headache, nausea, vomiting)
  4. Hypopituitarism (occasionally)
  5. Pituitary apoplexy (rarely)
  6. Mild hyperprolactinaemia
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16
Q

Why is bitemporal hemianopia the typical VF defect seen with pituitary adenomas?

A

Proximity of sella turcica to decussating optic nerve fibres at level of optic chiasm

17
Q

Why can mild prolactinaemia be seen in pituitary adenomas that do not produce prolactin?

A

Due to disturbance of dopamine release from hypothalamus (dopamine has inhibitory effect on prolactin production)

18
Q

Clinical features of lactotroph adenoma

A
  1. Amenorrhoea (causes ~1/4 of all cases of amenorrhoea)
  2. Galactorrhoea
  3. Loss of libido
  4. Infertility
19
Q

Clinical features of somatotroph adenoma

A
  1. Gigantism (in children prior to closure of epiphyses)
  2. Acromegaly (adults or children post closure of epiphyses)
  3. Wide range of metabolic disturbances including: gonadal dysfunction, diabetes mellitus, generalised muscle weakness, HTN, arthritis, CCF, increased risk of GI cancers
20
Q

How are many of the clinical features of gigantism mediated?

A

GH stimulates hepatic secretion of IGF-1

21
Q

Clinical features of gigantism

A

Generalised increase in body size with disproportionately long arms and legs

22
Q

Clinical features of acromegaly

A
  1. Growth of skin and soft tissues; viscera (thyroid, heart, liver, adrenals); and bones of face, hands and feet
  2. Hyperostosis (increased bone density) in spine and hips
  3. Enlargement of jaw causes prognathism (protrusion) and broadening of lower face
23
Q

How do the symptoms of somatotroph adenoma change with treatment?

A

Characteristic tissue overgrowth and related symptoms recede with treatment, and metabolic abnormalities improve

24
Q

Clinical features of corticotroph adenoma

A
  1. Cushing syndrome (called Cushing disease when caused by pituitary adenoma)
  2. Nelson syndrome
25
Q

What is Nelson syndrome and what causes it? How do patients present?

A

Development of large destructive pituitary adenoma post-adrenalectomy for treatment of Cushing syndrome
Due to loss of inhibitory effect of adrenal corticosteroids on corticotroph microadenoma
Hypercortisolism does not result because adrenals are absent, but patients can present with mass effects and with hyperpigmentation due to trophic effects of melanotropin (derived from POMC) on melanocytes

26
Q

Clinical features of gonadotroph adenoma

A
  1. Generally non-functional (most frequently present in middle-aged men and women with neurologic symptoms)
  2. Impaired LH secretion (may be due to impairment of function of normal gonadotrophs by adenoma, or by negative feedback of high oestrogens on LH secretion)
27
Q

How does a functional gonadotroph adenoma present?

A

Decreased testosterone in males (decreased energy and libido)
Amenorrhoea in premenopausal females

28
Q

Treatment of lactotroph adenomas

A

Bromocriptine (dopamine receptor agonist)

Surgery

29
Q

Treatment of somatotroph adenoma

A

Somatostatin analogues (e.g. octreotide)
GH receptor antagonists (e.g. pegvisomant)
Surgery

30
Q

Diagnosis of somatotroph adenoma

A

Elevated serum GH and IGF-1

GH suppression test (failure to suppress GH production in response to oral glucose load)

31
Q

Hormones produced by mammosomatotroph adenoma

A

PRL + GH

32
Q

Which cells of the anterior pituitary arle acidophilic and which are basophilic?

A

Acidophilic: somatotrophs, lactotrophs
Basophilic: corticotrophs, thyrotrophs, gonadotrophs

ACEM Primary Written (150 decks)

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