Histo: Endocrine disease Pt.2 Flashcards

1
Q

Describe the effect of TSH receptor-stimulating antibodies.

A

They stimulate thyroid hormone release and increase proliferation of the thyroid epithelium.

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2
Q

What is the triad of Grave’s?

A
  • Hyperthyroidism
  • Infiltrative ophthalmopathy - exopthalmos (40%)
  • Infiltrative dermopathy - pretibial myoedema (minority)

Also associated with other autoimmune diseases e.g. SLE, T1DM, pernicious anaemia, Addison’s

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3
Q

List some primary and secondary causes of hypothyroidism.

A

Primary

  • Post-ablative
  • Autoimmune (Hashimoto’s)
  • Iodine deficiency
  • Congenital biosynthetic defect

Secondary

  • Pituitary or hypothalamic failure (uncommon)
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4
Q

Describe the presentation of Hashimoto’s thyroiditis.

A
  • Painless enlargement of the thyroid gland
  • Symptoms of hypothyroidism.
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5
Q

Describe the histology of Hashimoto’s thyroiditis.

A
  • There are lots of lymphoid cells with germinal centres
  • The epithelial cells become large with lots of eosinophilic cytoplasm (Hurthle cells)
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6
Q

Types of thyroid neoplasms:

A
  • Adenoma - benign tumours of follicular epithelium
  • Carcinoma - uncommon (accounts for < 1% of solitary thyroid nodules)
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7
Q

List some features of a thyroid lump that would be suggestive of neoplasia.

A
  • Solitary rather than multiple
  • Solid rather than cystic
  • Younger patients
  • Male more than female
  • Less likely to take up radioiodine (cold nodules)
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8
Q

How thyroid neoplasms diagnosed?

A
  • Fine needle aspiration cytology
  • Histology
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9
Q

List some features of adenomas of the thyroid gland.

A
  • Usually solitary
  • Well circumscribed
  • Well-formed capsule
  • Small proportion will be functional
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10
Q

List the four types of thyroid cancer in order of decreasing prevalence.

A
  • Papillary (80%)
  • Follicular (15%)
  • Medullary (5%)
  • Anaplastic (< 5%)
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11
Q

What are some risk factors for thyroid cancer?

A
  • Genetic factors (e.g. MEN)
  • Ionisation radiation (mainly papillary)
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12
Q

What is the histological features of papillary thyroid cancer?

A

Nuclear features

  • Optically clear nuclei (Orphan Annie Eye)
  • Intranuclear inclusions

There may also be psammoma bodies (round calcifications)

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13
Q

What are some clinical features of papillary thyroid cancer?

A
  • Non-functional
  • Presents with painless neck lump
  • Can metastasize
  • 90% 10 year survival
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14
Q

Where does papillary thyroid cancer tend to metastasise to?

A

Cervical lymph nodes

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15
Q

Where does follicular thyroid cancer tend to metastasise?

A

Lungs, bone and liver (via the bloodstream)

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16
Q

Which cells are medullary thyroid cancers derived from?

A

Parafollicular C cells

NOTE: 80% are sporadic (50-60 yrs), 20% are familial (MEN - younger patients)

17
Q

What tends to happen to the calcitonin produced by tumour cells in medullary thyroid cancer?

A
  • It is broken down and deposited as amyloid within the thyroid
18
Q

What is the most aggressive thyroid cancer?

A

Anaplastic

  • Occurs in elderly
  • Metastases common
  • Usually death in < 1 year
19
Q

What are the parathyroid glands derived from?

A

Developing pharyngeal pouches

20
Q

What controls PTH secretion?

A

Serum calcium concentration (sensed by CaSR)

21
Q

List the actions of PTH.

A
  • Activates osteoclasts
  • Increased renal absorption of calcium
  • Increases activation of vitamin D
  • Increases urinary phosphate exretion
  • Increases intestinal calcium absorption
22
Q

What is hyperparathyroidism usually caused by?

A
  • 80% solitay adenoma
  • 20% due to hyperplasia of all four glands (sporadic or part of MEN1)
  • < 1% carcinoma
23
Q

Describe the histological appearance of a parathyroid adenoma.

A

Very cellular tissue with no fat (whereas the normal parathyroid gland is quite fatty)

24
Q

What bone change is seen in hyperparathyroidism?

A

Osteitis fibrosa cystica - caused by bone resorption with thinning of the cortex

25
Q

What are the effects of primary hyperparathyroidism?

A
  • Bone - increased resorption (OFC)
  • Kidneys - stones and obstructive nephropathy
  • GI - constipation, pancreatitis, gallstones
  • CNS - depression, lethary, seizures
  • Muscular weakness
  • Polyuria and polydipsia

“Painful bones, renal stones, abdominal groans, psychic moans”