Endocrinology: Pathology - Adrenal cortex and medulla Flashcards

1
Q

List six causes of Cushing syndrome. Which of these are ACTH-dependent and which are ACTH-independent? Which is most common?

A
  1. Exogenous glucocorticoids (most common)

ACTH-dependent:
2. ACTH-secreting pituitary adenomas (most common ACTH-dependent, 70%; “Cushing disease”)
3. Corticotroph cell hyperplasia (primary or secondary due to hypothalamic dysfunction with raised CRH)
4. Ectopic ACTH secretion by non-pituitary tumours

ACTH-independent:
5. Primary adrenal neoplasm
6. Primary cortical hyperplasia (rare)

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2
Q

What is the most common non-pituitary tumour to secrete ACTH?

A

Small cell lung Ca

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3
Q

Which primary adrenal neoplasm causes more marked hypercortisolism?

A

Carcinoma

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4
Q

What are the four morphological patterns seen in the adrenal gland in the setting of hypercortisolism, and what causes each?

A
  1. Focal atrophy: due to exogenous glucocorticoids
  2. Diffuse hyperplasia: due to ACTH-dependent causes
  3. Micronodular and macronodular hyperplasia: primary hyperplasia
  4. Pituitary adenoma or carcinoma
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5
Q

What derangements in serum ACTH and response to dexamethasone suppression test are seen in the setting of pituitary causes of Cushing syndrome vs ectopic ACTH syndromes vs adrenal tumours?

A

Pituitary causes:
- Increased ACTH
- No change in ACTH or urinary cortisol excretion with low doses
- Reduced ACTH and suppression of urinary cortisol excretion with higher doses

Ectopic ACTH:
- Increased ACTH
- No change in ACTH or urinary cortisol excretion with low or high doses

Adrenal tumours:
- Decreased ACTH (due to negative feedback)
- No change in ACTH or urinary cortisol excretion with low or high doses

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6
Q

List three causes of primary hyperaldosteronism. Which of these is most common?

A
  1. Bilateral idiopathic hyperaldosteronism (most common, 60%)
  2. Adrenocortical neoplasm (aldosterone-producing adenoma, adrenocortical carcinoma)
  3. Primary familial hyperaldosteronism (including glucocorticoid-suppressible)
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7
Q

What is Conn syndrome?

A

Hyperaldosteronism caused by aldosterone-secreting adenoma

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8
Q

Describe three broad causes of secondary hyperaldosteronism with specific examples of each

A
  1. Decreased renal perfusion (e.g. renal artery stenosis, arteriolar nephrosclerosis)
  2. Arterial hypovolaemia and oedema (e.g. CCF, cirrhosis, nephrotic syndrome)
  3. Pregnancy
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9
Q

What is the pathogenesis of pregnancy-induced hyperaldosteronism?

A

Due to oestrogen-induced increase in plasma renin

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10
Q

What is the difference in plasma renin activity between primary and secondary causes of hyperaldosteronism?

A

Primary: decreased plasma renin activity with increased aldosterone:renin activity ratio (must be confirmed with aldosterone suppression test)
Secondary: increased plasma renin activity

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11
Q

Describe the clinical presentation of primary and secondary hyperaldosteronism

A

Both present with HTN, and Na+ and fluid retention
Primary hyperaldosteronism may also present with hypokalaemia

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12
Q

Describe two broad causes of primary adrenocortical insufficiency with specific examples of each

A
  1. Loss of cortex (e.g. congenital hypoplasia, AI adrenalitis, infection, systemic AI conditions such as sarcoidosis and amyloidosis, metastatic carcinoma)
  2. Failure of metabolism (e.g. congenital hyperplasia, drug- or steroid-induced ACTH inhibition)
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13
Q

Describe two broad causes of secondary adrenocortical insufficiency with specific examples of each

A
  1. Hypothalamic-pituitary disease (e.g. neoplasm, infection, infiltrative disease such as sarcoidosis, inflammation)
  2. Hypothalamic-pituitary suppression (e.g. long-term steroid administration, steroid-producing neoplasms)
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14
Q

What are the three syndromes that adrenocortical insufficiency may present as?

A
  1. Primary acute adrenocortical insufficiency
  2. Primary chronic (Addison disease) adrenocortical insufficiency
  3. Secondary adrenocortical insufficiency
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15
Q

Give three causes of primary ACUTE adrenocortical insufficiency

A
  1. Acute stress (e.g. surgery, infection) in setting of chronic adrenocortical insufficiency
  2. Rapid withdrawal of exogenous steroids after prolonged treatment
  3. Massive adrenal haemorrhage (e.g. in newborns, Waterhouse-Friderichsen syndrome)
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16
Q

What is Waterhouse-Friderichsen syndrome? Who does it most commonly affect?

A

Acute adrenal failure due to adrenal haemorrhage secondary to severe bacterial infection
More common in children

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17
Q

What is the usual causative organism in Waterhouse-Friderichsen syndrome? What are some other implicated organisms?

A

N. meningitidis
May also be caused by Pseudomonas, streptococcus, Haemophilus influenzae, staphylococci

18
Q

Four features of Waterhouse-Friderichsen syndrome

A
  1. Sepsis
  2. Hypotension -> shock
  3. DIC with widespread purpura
  4. Acute adrenocortical insufficiency
19
Q

What causes >90% of cases of Addison disease?

A

Autoimmune adrenalitis
Tuberculosis
AIDS
Metastatic cancers

20
Q

What is the most common cause of Addison disease?

A

Autoimmune adrenalitis

21
Q

Which two autoantibodies are implicated in autoimmune adrenalitis?

A

Antibodies to 21-hydroxylase and 17-hydroxylase

22
Q

What are the two underlying syndromes which cause autoimmune adrenalitis and what are their other features?

A
  1. APS1: with polyendocrinopathy and skin changes (due to AIRE mutation)
  2. APS2: with autoimmune thyroiditis or T1DM, no skin changes
23
Q

What are the most common infectious causes of Addison disease?

A

Tuberculosis
Fungi (e.g. Histoplasma capsulatum)

24
Q

How does AIDS cause adrenal insufficiency?

A

May be due to opportunistic infection (e.g. CMV, MAC) or malignancy (e.g. Kaposi sarcoma)

25
Q

Which two metastatic cancers most commonly cause Addison disease?

A

Lung
Breast

26
Q

Describe five clinical features of Addison disease

A
  1. Non-specific progressive weakness and fatigue
  2. GI disturbances: anorexia, nausea and vomiting, diarrhoea, weight loss
  3. Hyperpigmentation
  4. Hypoaldosteronism: hyperkalaemia, Na+ and fluid loss leading to volume depletion and hypotension
  5. Acute crisis if stressed
27
Q

Three clinical features of acute adrenal crisis

A
  1. Intractable vomiting
  2. Abdominal pain
  3. Cardiovascular collapse
28
Q

What causes the hyperpigmentation seen in Addison disease?

A

Due to increased production of POMC, precursor to ACTH but also MSH -> stimulates melanocytes

29
Q

Which clinical feature of Addison disease differentiates it from secondary causes of adrenocortical insufficiency?

A

Hyperpigmentation not seen in secondary adrenocortical insufficiency (because ACTH release is decreased)

30
Q

What is phaeochromocytoma?

A

Adrenal medullary neoplasm composed of chromaffin cells which secrete catecholamines (but may also secrete peptide hormones or other steroids, including cortisol)

31
Q

What is the “rule of 10s” of phaeochromocytoma?

A
  • 10% extra-adrenal (“paragangliomas”)
  • 10% sporadic cases are bilateral (50% if familial)
  • 10% malignant
  • 10% not associated with HTN
  • Now 25% (previously thought to be 10%) associated with germline mutations (e.g. von Hippel-Lindau, NF1, Sturge-Weber, MEN)
32
Q

Describe the clinical presentation of phaeochromocytoma

A

90% have HTN
Two-thirds present with paroxysmal catecholamine release, characterised by episodic diaphoresis, headache, anxiety, tremor, visual disturbance, abnormal pain and nausea

33
Q

List three malignancies associated with MEN-1. Which of these are most common?

A

3 (+1) P’s:
1. Parathyroid (most common)
2. Pancreas (endocrine)
3. Pituitary (usually Prolactinoma)

34
Q

List three malignancies associated with MEN-2

A
  1. Phaeochromocytoma
  2. Medullary carcinoma
  3. Parathyroid hyperplasia
35
Q

What is pre-eclampsia and how does it present?

A

Systemic syndrome characterised by widespread maternal endothelial dysfunction, likely due to placental ischaemia
Presents with HTN, oedema and proteinuria (usually in third trimester)

36
Q

In which demographic is pre-eclampsia more common?

A

Primiparas

37
Q

Five symptoms which suggest severe pre-eclampsia (with likelihood of transition to eclampsia)

A
  1. Hypercoagulability
  2. AKI
  3. Pulmonary oedema
  4. Headache
  5. Visual disturbances
38
Q

What is eclampsia?

A

Severe form of pre-eclampsia characterised by seizures

39
Q

What is HELLP syndrome? How common is it?

A

Occurs in 10% of women with eclampsia
Characterised by:
- Haemolysis
- Elevated Liver enzymes
- Low Platelets

40
Q

Describe the three pathogenic factors involved in pre-eclampsia

A
  1. Abnormal placental vasculature -> placental ischaemic
  2. Endothelial dysfunction
  3. Coagulation abnormalities: decreased PGI2, increased thromboxane
41
Q

Six morphological features seen in the placenta in pre-eclampsia

A
  1. Placental infarcts and villous ischaemia with hypovascularity
  2. Fibrinoid necrosis
  3. Retroplacental haemorrhage
  4. Intramural lipid deposition
  5. Prominent syncytial knots
  6. Thickened trophoblastic basement membrane