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RB Y2 Endocrine - 2 Thyroid > Thyroid Nodules > Flashcards

Thyroid Nodules Flashcards

1
Q

solitary thyroid nodules - proportion of benign and malignant

A

5% malignant

95% benign

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2
Q

benign solitary thyroid nodules

A

cyst

benign follicular adenoma

hyperplastic nodule

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3
Q

what are most malignant nodules

A

papillary thyroid carcinoma - 95%

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4
Q

how would one determine if the nodule was in the thyroid

A

if it moves upwards on swallowing

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5
Q

what fascia are the thyroid gland and thryoglossal duct invested in

A

pre tracheal fascia

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6
Q

pain?

A

uncommon feature

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7
Q

risk factors

A
  • Previous irradiation
  • E.g. MEN2 (medullary thyroid)
  • Family history
  • Low iodine diet
  • note, smoking and lifestyle have no influence
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8
Q

determinants in history

A

previous neck irradiation predisposes one to thyroid cancer

FH

  • there is no association with lifestyle factors, smoking or other malignancies
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9
Q

neck lymph node involvement on examination

A

papillary thyroid carcinoma until proven other wise - this spreads via the lymph nodes

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10
Q

hoarseness on examination

A

indication of recurrent laryngeal nerve palsy, as this supplies the vocal chords

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11
Q

investigations

A
  • TSH for thyroid status
  • Thyroid antibodies to exclude autoimmune aetiology
  • US
    • Delineate nodule and demonstrate whether they are cystic or solid
  • Chest and thoracic X ray/CT
    • Detect tracheal compression and large retrosternal extensions
  • USS-FNA (US Guided Fine Needle Aspiration)
    • Gives no indication of the morphology of the lump
  • Radionuclide scan
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12
Q

what investigation is performed if recurrent laryngeal nerve palsy is suspected

A

pre operative laryngoscopy

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13
Q

radionuclide scan of thyroid

A

used to diagnose thyroid problems

  • low uptake suggests thyroiditis
  • high uptake suggests Grave’s
  • uneven uptake suggests a nodule
    • cold/hypofunctioning - malignant
    • hot/hyperfunctioning - adenoma
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14
Q

toxic adenoma

A
  • produce thyroid hormones causing hyperthyroidism and suppressed TSH
  • positive uptake on scan - hot nodule
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15
Q

what are the clinical predictors of malignancy

A
  • new thyroid nodule aged <20 or >50
  • male
  • nodule increasing in size
  • lesion >4cm in diameter
  • history of head and neck irradiation
  • vocal cord palsy
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16
Q

what are the FNA and USS stages used

A
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17
Q

Thy1 on FNA

A

only blood aspirated, no cells

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18
Q

what percentage of Thy3 and U3 are malignant

A

30%

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19
Q

what does differentiated refer to

A

how much the histological appearance and physical characteristics of the tumour are like the normal tissue they came from

well differentiated will look and behave like normal cells (eg take up iodine and produce thyroglobulin - TSH driven) and spread more slowly

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20
Q

incidence of DTC

A

5% incidence in females, rates increase from 15-40 then plateau

in males there is a steady increase with age

the incidence is rising, but the mortality is falling

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21
Q

epidemiology of DTC

A

seen worldwide, lower incidence in Afro-Americans

strong association with exposure to radiation: medical or environmental

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22
Q

common presentation of DTC

A

majority present with palpable nodules

a small percentage are chance findings on a histological section of thyroidectomy tissue

5% present with local or disseminated metastases

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23
Q

what is used as a marker of tumour

A
  • thyroglobulin - papillary and follicular cancers produce thyroglobulin, can be used as a marker and for follow up
  • calcitonin for medullary cancers
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24
Q

papillary thyroid cancer

A

95% of thyroid carcinomas

are found in younger patients

spread via the lymph nodes mainly, less so by blood

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25
Q

TFT for papillary thyroid cancer

A

TSH lower level of normal (0.4-4 mU/L)

Tg

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26
Q

what does papillary thyroid cancer increase the risk of

A

Hashimoto’s thyroiditis

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27
Q

prognosis of papillary thyroid cancer

A

very good with 10 year mortality rate being under 5%

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28
Q

who do follicular thyroid cancers tend to occur in

A

middle aged

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29
Q

where is the incidence of follicular thyroid cancers slightly higher

A

regions of relative iodine deficiency

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30
Q

what does the diagnosis of follicular thyroid cancers depend on

A

whether the capsule and vasculature has been invaded

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31
Q

how do follicular thyroid cancers spread

A

via the blood

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32
Q

medullary thyroid cancer

A

tumour of the parafollicular cells, which secrete calcitonin - this can be used as a tumour cell marker

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33
Q

how can medullary thyroid cancer be diagnosed

A

on FNA, or by the presence of amyloid or calcitonin positive stains

34
Q

who is lymphoma of the thyroid gland often seen in

A

females, on a background of autoimmune hypothyroidism, and hence longstanding thyroxine treatment

35
Q

how does lymphoma tend to present

A

sudden onset of mass in the thyroid

may present with stridor or dysphagia

36
Q

treatment and diagnosis of lymphoma

A

core biopsy for histology diagnosis

then chemo/radio, or steroids if patient is acutely unwell

37
Q

anaplastic carcinoma

A
  • Poorly differentiated, very aggressive
  • Local invasion is common
  • Most commonly presents in the elderly as a hard lump in the thyroid
  • Responsible for 50% of deaths due to thyroid malignancies.
38
Q

outline management of DTC

A
39
Q

what risk stratification is used in Ninewells

A

AMES

Age

Metastases

Extent of primary tumour

Size of primary tumour

40
Q

low risk AMES group

A

aged<50, tumour <4cm and no evidence of metastases

OR, older patients with intrathyroidal papillary lesion, minimally invasive follicular lesions and primary tumour <5cm and no distant metastases

TSH lower range/normal, baseline Tg

41
Q

what is the 20 survival rate for low risk group

A

99%

42
Q

treatment for low risk group

A

lobectomy with isthmusectomy

  • less invasive with a lower morbidity
  • however, the leftover thryoid may be a source of further malignancies
43
Q

high risk AMES group

A

all patients with distant metastases, primary tumour >5cm in older patients

≥T3

TSH <1

44
Q

what is the 20 year survival rate for the high risk group

A

61%

45
Q

treatment for the high risk group

A

total or subtotal thyroidectomy

46
Q

how much of the thyroid does a subtotal thyroidectomy leave

A

5-10%

47
Q

lymph node surgery?

A

controversial area, patients with macroscopic lymph node disease should undergo nodal clearance

48
Q

post operative care

A

patient must be discharged with thyroxine supplementation eg levothryoxine

49
Q

thyroid surgery complications

A
  • It carries a risk of damage to the recurrent laryngeal nerve (hoarseness several days after surgery)
  • Bleeding: haematomas may rapidly develop leading to respiratory compromise owing to laryngeal oedema
  • Damage to the parathyroid glands resulting in hypocalcaemia
  • Thyroid storm
50
Q

what is performed after surgery

A
  • Thyroid remnant ablation is performed after surgery, particularly in high risk patients.
  • Thyroid cells store radio-iodine, it accumulates in them and destroys any leftover gland.
51
Q

what is performed prior to TRA

A

whole body iodine scanning

52
Q

ideal level of TSH for iodine sensitivity

A

>20

53
Q

how long after op is iodine scanning performed

A

3-6 months

54
Q

preparation for iodine scanning

A
  • TSH levels must be high (as the cancer cells are TSH driven/dependent high levels of TSH will make the cancer cells ‘hungry’ for the radio iodine)
    • recombinant human TSH (rsTSH) is given
    • or Thyroid medication must be stopped: T4 4 weeks prior and T3 2 weeks prior
55
Q

what is the benefit of rsTSH

A

patients do not have to stop their normal thyroxine medication

56
Q

when would the rsTSH be given

A

about 4 days before, then oral I-131 adminstered 2 days before

57
Q

what is the rationale for TRA

A

ablate residual thyroid tissue in order to destroy occult microfoci

58
Q

pre treatment for TRA

A

rsTSH and then adminstered a high dose of oral I-131

59
Q

side effects of radio iodine

A

few

sialadenitis (infection of salivary gland) and sore throat sometimes seen

60
Q

how much iodine is excreted within the first 24 hours

A

80%

61
Q

follow up of TRA

A

TSH levels must be kept low now to prevent recurrence

aim for TSH <0.1 mU/L and fT4 <24

62
Q

what can be used as a tumour marker after treatment

A

Tg - should be close to 0 as all Tg secreting cells should eb destroyed

apart from in lobectomy - almost impossible to interpret in this case

Tg measured pre-operatively to provide a comparison and anti-Tg antibodies measured as well

63
Q

how is recurrent disease detected

A

Tg rising

imaging

Recurrence in the cervical lymph nodes is more common in papillary cancer, whereas haematogeneous spread to the lungs, bone or brain is more common in follicular lesions.

64
Q

who is recurrent disease more common in

A

those whose Tg levels did not fully fall to 0

it tends to occur within the first 2 years, so for this reason patients are screened every 2 months for the first 2 years

65
Q

what investigation is recommended in patients who have a rising Tg but negative whole body I-131 scan

A

PET scan - identify sites of disease to allow surgery/radio therapy to be targeted

66
Q

systemic anti cancer therapy

A

there is evolving evidence for protein kinase inhibitors Sorafenib and Lenvatinib

67
Q

prognosis of metastatic or recurrent disease

A

still good

68
Q

T1

A

tumour size <2 cm

69
Q

T2

A

tumour size between 2 and 4 cm

limited to the thyroid

70
Q

T3

A

tumour size >4cm

limited to the thyroid or any tumour with minimal extrathyroid extension

71
Q

T4a

A

tumour of any size extending beyind the thyroid capsuke to invade subcutaenous soft tissue, larynx, oesophagus, trachea or recurrent laryngeal nerve

contained in pre tracheal fascia

72
Q

T4b

A

very advanced disease

tumour invades preverterbal fascia or encases carotid artery or mediastinal vessels

73
Q

N0

A

no regional lymph node metastasis

74
Q

N1

A

regional lymph node metastases

N1a - metastases to level VI

N1b - metasteses to other levels

75
Q

M0 and M1

A

no/distant metastases present

76
Q

MNG

A

the most common goitre in the UK

50% of those who present with a single nodule actually have MNG

77
Q

what must be assessed in MNG

A

function of thyroid gland - TSH levels

structure of thyroid gland - CT scan

78
Q

what will TSH scan show in MNG

A

patients may be hyperthyroid or euthyroid

anti-thyroid drugs may be required

79
Q

purpose of CT scan in MNG

A

assess structure of the thyroid gland

determine which nearby structures are being squashed eg symptoms of stridor or choking when lying flat

  • retrosternal extension or tracheal compression
80
Q

management of MNG

A

most can be left alone

RAI may be indicated if there is significant hyperthyroidism

surgery is indicated if there is a structural problem eg tracheal compression or retrosternal extension

81
Q

describe the tracheal flow loops in intrathoracic and extrathoracic comrpession

A

intrathoracic = L

extrathoracic = R

NB tests may be normal in a sitting position, so consider a supine test

82
Q

when are tracheal flow loops indicated

A

if there are other respiratory problems causing orthopnoea/breathing difficulties

RB Y2 Endocrine - 2 Thyroid (8 decks)

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