Thyroid Nodules Flashcards
1
Q
solitary thyroid nodules - proportion of benign and malignant
A
5% malignant
95% benign
2
Q
benign solitary thyroid nodules
A
cyst
benign follicular adenoma
hyperplastic nodule
3
Q
what are most malignant nodules
A
papillary thyroid carcinoma - 95%
4
Q
how would one determine if the nodule was in the thyroid
A
if it moves upwards on swallowing
5
Q
what fascia are the thyroid gland and thryoglossal duct invested in
A
pre tracheal fascia
6
Q
pain?
A
uncommon feature
7
Q
risk factors
A
- Previous irradiation
- E.g. MEN2 (medullary thyroid)
- Family history
- Low iodine diet
- note, smoking and lifestyle have no influence
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
9
Q
neck lymph node involvement on examination
A
papillary thyroid carcinoma until proven other wise - this spreads via the lymph nodes
10
Q
hoarseness on examination
A
indication of recurrent laryngeal nerve palsy, as this supplies the vocal chords
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
12
Q
what investigation is performed if recurrent laryngeal nerve palsy is suspected
A
pre operative laryngoscopy
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
14
Q
toxic adenoma
A
- produce thyroid hormones causing hyperthyroidism and suppressed TSH
- positive uptake on scan - hot nodule
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
16
Q
what are the FNA and USS stages used
A
17
Q
Thy1 on FNA
A
only blood aspirated, no cells
18
Q
what percentage of Thy3 and U3 are malignant
A
30%
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
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
21
Q
epidemiology of DTC
A
seen worldwide, lower incidence in Afro-Americans
strong association with exposure to radiation: medical or environmental
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
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
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
25
TFT for papillary thyroid cancer
TSH lower level of normal (0.4-4 mU/L)
Tg
26
what does papillary thyroid cancer increase the risk of
Hashimoto's thyroiditis
27
prognosis of papillary thyroid cancer
very good with 10 year mortality rate being under 5%
28
who do follicular thyroid cancers tend to occur in
middle aged
29
where is the incidence of follicular thyroid cancers slightly higher
regions of relative iodine deficiency
30
what does the diagnosis of follicular thyroid cancers depend on
whether the capsule and vasculature has been invaded
31
how do follicular thyroid cancers spread
via the blood
32
medullary thyroid cancer
tumour of the parafollicular cells, which secrete calcitonin - this can be used as a tumour cell marker
33
how can medullary thyroid cancer be diagnosed
on FNA, or by the presence of amyloid or calcitonin positive stains
34
who is lymphoma of the thyroid gland often seen in
females, on a background of autoimmune hypothyroidism, and hence longstanding thyroxine treatment
35
how does lymphoma tend to present
sudden onset of mass in the thyroid
may present with stridor or dysphagia
36
treatment and diagnosis of lymphoma
core biopsy for histology diagnosis
then chemo/radio, or steroids if patient is acutely unwell
37
anaplastic carcinoma
* 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
outline management of DTC
39
what risk stratification is used in Ninewells
AMES
Age
Metastases
Extent of primary tumour
Size of primary tumour
40
low risk AMES group
**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
what is the 20 survival rate for low risk group
99%
42
treatment for low risk group
lobectomy with isthmusectomy
- less invasive with a lower morbidity
- however, the leftover thryoid may be a source of further malignancies
43
high risk AMES group
**all patients with distant metastases, primary tumour \>5cm in older patients**
≥T3
TSH \<1
44
what is the 20 year survival rate for the high risk group
61%
45
treatment for the high risk group
total or subtotal thyroidectomy
46
how much of the thyroid does a subtotal thyroidectomy leave
5-10%
47
lymph node surgery?
controversial area, patients with macroscopic lymph node disease should undergo nodal clearance
48
post operative care
patient must be discharged with **thyroxine supplementation eg levothryoxine**
49
thyroid surgery complications
* 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
what is performed after surgery
* **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
what is performed prior to TRA
whole body iodine scanning
52
ideal level of TSH for iodine sensitivity
\>20
53
how long after op is iodine scanning performed
3-6 months
54
preparation for iodine scanning
* 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
what is the benefit of rsTSH
patients do not have to stop their normal thyroxine medication
56
when would the rsTSH be given
about 4 days before, then oral **I-131** adminstered 2 days before
57
what is the rationale for TRA
ablate residual thyroid tissue in order to destroy occult microfoci
58
pre treatment for TRA
rsTSH and then adminstered a high dose of oral I-131
59
side effects of radio iodine
few
sialadenitis (infection of salivary gland) and sore throat sometimes seen
60
how much iodine is excreted within the first 24 hours
80%
61
follow up of TRA
TSH levels must be kept low now to prevent recurrence
aim for TSH \<0.1 mU/L and fT4 \<24
62
what can be used as a tumour marker after treatment
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
how is recurrent disease detected
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
who is recurrent disease more common in
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
what investigation is recommended in patients who have a rising Tg but negative whole body I-131 scan
PET scan - identify sites of disease to allow surgery/radio therapy to be targeted
66
systemic anti cancer therapy
there is evolving evidence for protein kinase inhibitors Sorafenib and Lenvatinib
67
prognosis of metastatic or recurrent disease
still good
68
T1
tumour size \<2 cm
69
T2
tumour size between 2 and 4 cm
limited to the thyroid
70
T3
tumour size \>4cm
limited to the thyroid or any tumour with minimal extrathyroid extension
71
T4a
tumour of any size extending beyind the thyroid capsuke to invade subcutaenous soft tissue, larynx, oesophagus, trachea or recurrent laryngeal nerve
## Footnote
**contained in pre tracheal fascia**
72
T4b
very advanced disease
tumour invades preverterbal fascia or encases carotid artery or mediastinal vessels
73
N0
no regional lymph node metastasis
74
N1
regional lymph node metastases
N1a - metastases to level VI
N1b - metasteses to other levels
75
M0 and M1
no/distant metastases present
76
MNG
the most common goitre in the UK
50% of those who present with a single nodule actually have MNG
77
what must be assessed in MNG
function of thyroid gland - TSH levels
structure of thyroid gland - CT scan
78
what will TSH scan show in MNG
patients may be hyperthyroid or euthyroid
anti-thyroid drugs may be required
79
purpose of CT scan in MNG
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
management of MNG
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
describe the tracheal flow loops in intrathoracic and extrathoracic comrpession
intrathoracic = L
extrathoracic = R
NB tests may be normal in a sitting position, so consider a supine test
82
when are tracheal flow loops indicated
if there are other respiratory problems causing orthopnoea/breathing difficulties
