Pathology of the Thyroid Gland Flashcards

(56 cards)

1
Q

What are the 4 main histological classifications of thyroid cancer?

A

Papillary - 6%
Follicular - 17%
Medullary - 3%
Anaplastic - 2%

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2
Q

What does differentiated thryoid cancer refer to?

A

Papillary and Follicular thryoid cancer

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3
Q

What do most DTCs do?

A

Take up iodine and secrete thyroglobulin - can act like normal thryoid cells
They are TSH driven

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4
Q

Decribe the rates of incidence of DTC in females and males.

A

Females - Rates increase from 15-40 then plateau

Males - Steady increase with age

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5
Q

How do DTC present?

A

Majority have palpable nodules
small % are chance findings
5% with local or disseminated mets

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6
Q

Give 5 points about Papillary thyroid cancer.

A
Associated with ionising radiation 
Usually solitary nodule 
Activates MAP kinase pathway 
Spreads via lymphatics - lungs, bone, liver and brain
Associated with Hasimoto's thyroiditis
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7
Q

Give 4 points about Folicular thyroid cancer.

A

Associated with iodine deficiency
Usually single slow growing nodule - painless and non-functional
Mutations in PI3K/AKT pathway
Spreads haematogenously

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8
Q

What is the prognosis of DTC?

A

Generally good with 10 year mortality <5%

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9
Q

What Ix are used for suspected DTC?

A

USS guided FNA

Excision biopsy of lumh node

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10
Q

What are the clinical predictors of DTC?

A
New thyroid nodule 50 y.o 
Nodule increased in size 
Male 
Lesion >4cm 
History of head and neck irridation 
Vocal cord palsy - do pre-operative laryngoscopy
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11
Q

What exactly is the best management option for DTC?

A

Sub total thyroidectomy with RAI

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12
Q

What risk stratification tool is used post op for patients with DTC and why is this used?

A
A - age 
M - ets 
E - extent of primary tumour 
S - Size of primary tumour
Used to stratify pts as low or high risk
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13
Q

When and why is whole body iodine scanning used?

A

Pts who have had total or sub-total thyroidectomy
Given low dose iodine capsule which will be taken up by thyroid and any DTC cells in the body to see of tumour all removed or mets

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14
Q

If uptake at thyroid bed >0.1% of ingested activity, what does the patient undergo?

A

Thyroid remnant ablation

then whole body iodine scan repeated to ensure uptake in thyroid bed now <0.1%

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15
Q

What can be used as a tumour marker in DTC?

A

Thyroglobulin - produced by DTC cells and normal thyroid cells but 0 from them as removed

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16
Q

What is a follicular adenoma?

A

Discrete solitary mass derived from thyroid follicular cells encapsulated by a surrounding collagen cuff –> very well circumbscribed

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17
Q

Is a follicular adenoma functional or non-functional?

A

Usually non-functional but can secrete thyroid hormones

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18
Q

Can medullary thyroid cancers be familial?

A

Yes (bilateral/ mulitcentric) or sporadic (solitary nodule)

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19
Q

What are medullary thryoid cancers composed of?

A

Spindle or polygonal cells arranged in nest, trabeculae or follicles

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20
Q

What can medullary thyroid cancers cause?

A

dysphagia
hoarseness
airway compromise

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21
Q

Give 4 points about Anaplastic thyroid cancer.

A

Undifferentiated and aggressive tumours
Usually older patients
May occur in pts with a history of DTC
Rapid growth and involvement of neck structures and death

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22
Q

What is the Thy scale and why is it used?

A

Thy 1 - insufficient sample
Thy 2 - benign
Thy 3 - atypia probably benign/ equivocal
Thy 4 - atypia suspicious of malignancy
Thy 5 - malignant
USS FNA used to provide a minimally invasive assessment of the likelihood of malignancy

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23
Q

What can cause primary hyperparathyriodism?

A

Adenoma involving a single gland or hyperplasia involving all glands

24
Q

What causes secondary hyperparathyroidism?

A

Chronic hypocalcaemia causes compensatory over activity of parathyroid glands

25
What causes tertiary hyperparathyroidism?
Parathyroid activity becomes autonomous associated with hypercalcaemia
26
What causes hypoparathyroidism?
Usually post-operatively (removal by accident) Rarely congenital absence - DiGeorge syndrome Familial - associated with primary adrenal insufficiency and mucocutaneous candidiasis (AI basis)
27
What is the most common cause of hyper/hpothyroidism?
Autoimmune thyroid disease
28
What blood results would you expect to see from primary hyperthyroidism?
TSH low | T4/T3 high
29
What blood results would you expect to see from primary hypothyroidism?
TSH high | T4/T3 low
30
What blood results would you expect to see from secondary thyroid disease - pituitary gland failure?
TSH low | T4/T3 low
31
What blood results would you expect to see from secondary thyroid disease - TSHoma?
TSH high | T4/T3 high
32
What blood results would you expect to see from primary subclinical hypothyroidism?
TSH high T3/T4 normal Probably end up as overt hypothyroidism
33
Define hypothyroidism.
Results from a variety of abnormalities that cause insufficiet secretion of thryoid hormones
34
What causes primary hypothyroidism?
Iodine deficiency #1 AI - Hashimoto's thyroiditis #1 Hereditary biosynthetic defects Maternally transmitted antithyroid agents, iodides Drug induced - amiodarone, lithium, thalidomide
35
What can cause secondary hypothyroidism?
Hypothalamic - congenital, infiltration, infection, malignancy Pituitary - Panhypopituitarism, isolated TSh deficiency
36
What are the symptoms of hypothyroidism?
``` tiredness/ malaise Weight gain Cold intolerance Goitre Contipation Menorrhagia - later oligo or ammenorrhoea Arthralgia Myalgia Physchosis Poor libido ```
37
What are the signs of hypothyroidism?
``` Dry skin and dry thin hair Periorbital puffiness Pitting oedema Mental slowness Slow relaxing reflexes Carpal tunnel syndrome Hyperprolactinaemia bradycardia worsening of heart failure ```
38
What Ix should be used for hypothyroidism and what would their positive result be?
``` TSH high T4/T3 low Elevated CK Increases LDL cholesterol Hyponatraemia Hyperprolactinaemia Macrocytosis is typical – rule out a concurrent Vit B12 deficiency ```
39
What is Hashimoto's Thyroiditis?
Gradual autoimmune destruction through antibody dependent cell mediated cytotoxicity, of the thyroid gland resulting in decreased thyroid hormone production
40
What autoantibodies are present in Hashimoto's thyroiditis?
Anti-TPO (95%) Anti-thyroglobulin antibody (60%) TSH receptor antibody (10-20% - blocking)
41
How is hypothyrodism managed?
Restore normal metabolic rate gradually younger pts - thyroxine at 50-100mcg daily elderly with history of IHD - thyroxine at 25-50mcg daily - adjusted every 4 weeks according to response
42
In pregnancy the dose requirements of thyroxine increaaase by how much?
25-50% (increased TBG)
43
Who is usually affected by a myxoedema coma?
Elderly women with longstanding but frequently unrecognised/ untreated hypothyrodisim
44
How does a myxoedema coma present?
bradycrdia | type 2 respiratory failure
45
If a patient is on amiodarone, what should they have checked frequently?
TFTs
46
List some causes of Hyperthyroidism
``` Graves disease Multi-nodular goite Toxic nodule (adenoma) Subacute thyroiditis/De Quervains Post-partum thyroiditis Rare - iodine and medications (amiodarone, lithium, kelp) ```
47
List the symptoms of hyperthyroidism.
``` Tremor Palpitations Sweating Irritability Diarrhoea Weight loss Lighter/less frequent periods increased appetite intolerance to heat ```
48
What are the clinical signs of hyperthyriodism?
``` Tachycardia or AF Proximal muscle wasting goitre with bruit warm peripheries lid lag palmar erythema onycholysis ```
49
What are the treatment options for hyperthyriodism?
``` Carbimazole Propylthiouracil Fluid restriction Radioiodine and surgery may also be considered Symptom Tx = beta-blocker (Propanolol) ```
50
What positive investigations indicate Graves disease?
High T3/T4, low TSh Anti-TPO +ve (70-80% Anti-thyroglobulin +ve (30-50%) TSH receptor antibody +ve (70-100% - stimulating)
51
What additional S&S are present in Grave's disease?
``` Exophalmus Chemosis visual loss proptosis diplopia pretibial myxoedema ```
52
What may trigger De Quervains?
Viral infection - other symptoms ay be present - sore throat, fever, etc)
53
What blood results are seen in De Quervains?
T4 - high in early stage, low in late stage then normal | TSH - low in early stage, high in late stage then normal
54
What treatment is required for a thyroid storm?
``` ABCDE May require ventilation Lugol's iodine Glucocorticoids PTU beta-blocker fluids monitoring ```
55
How does a thyroid storm present?
Respiratory and cardiac collapse Hypertermia Exaggerated reflexes
56
What precautions should be followed if you are on radio-active iodine?
avoid close prolonged contact with children and pregnancy women Avoid sharing a bed for x days avoid pregnancy for 6-12 months ensure not pregnant at start high risk of hypothyroidism (esp. in Graves)