thyroid Flashcards

1
Q

What histological features are seen in papillary thyroid cancer

A

Orphan Annie nuclei
psammoma bodies

Psammoma bodies also seen in ovarian cancer and meningioma

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2
Q

Why can follicular thyroid cancer not be diagnosed on FNA

A

Needs capsule or vascular invasion, so can only be seen at thyroidectomy

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2
Q

What is the complication of Hurthle cell variant FTC

A

Does not take up RAI

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3
Q

What cells do medullary thyroid cancer arise from
What needs to be screened for
What is the treatment for MTC

A

Parafollicular c cells
Need to be screened for MEN2
Tx is surgery as far as possible

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4
Q

What features distinguish FAP from Gardners syndrome

A

Extra teeth

Colorectal adenomatous polyps, osteomas (skull & mandible), desmoid tumours, desmoid cysts, sebaceous cysts

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5
Q

What is Turcot syndrome

A

AD

Colonic polyps associated with CNS tumours (ependymomas and medulloblastomas)

Increased risk of thyroid/adrenal/BCC

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6
Q

What is Cowdens syndrome and what is the lifetime risk of thyroid cancer

A

AD PTEN mutation - hamartoma syndrome
30-40% lifetime risk of thyroid cancer (follicular, then papillary)
Also breast, endometrial, colorectal, melanoma

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7
Q

How is a T1 thyroid cancer defined

T2

A

tumour <2cm
T1a = <1cm
T1b = 1-2cm

T2 = 2-4cm

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8
Q

How is a T3 thyroid cancer defined

A

T3a - >4cm but limited to thyroid
T3b - extra thyroid extension

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9
Q

How is a T4 thyroid cancer defined

A

T4a - Local invasion into trachea, larynx, oesophagus, recurrent laryngeal nerve

T4b - Invasion into prevertebral fascia, mediastinal vessels or carotids

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10
Q

How is thyroid nodal staging defined

A

N1a - Involvement of level 6 or 7
N1b - involvement elsewhere

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11
Q

When is cross sectional imaging indicated for thyroid cancer

A

T3-4 disease ie evidence of local invasion or tumour >4cm

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12
Q

What are the indications for a hemithyroidectomy

A

T1a (<1cm) - T2 differentiated thyroid cancer

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13
Q

What are the indications for a total thyroidectomy

A

T3-4
Nodal involvement
Extra-thyroid spread, multifocal disease
High risk features
Pre-RAI - distant mets

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14
Q

What are the indications for radioactive iodine

A

Post total thyroidectomy

Tumour >4cm (T3)
>T1b with unfavourable characteristics (Tall cell, Columnar, Insular, Diffuse sclerosing papillary cancer, Poorly differentiated)
Gross extra-thyroidal extension
Distant metastases
Recurrence

RAI not indicated if all of:
Tumour <1cm unifocal or multifocal
Classic papillary or follicular variant of papillary or follicular thyroid cancer
No vascular invasion AND no extra-thyroid extension

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15
Q

what are the RAI doses and indications

A

1.1Gbq - T1b-T3, N0 with R0 resection

3.7GBq - T4 or N1 disease or metastatic disease

5.5GBq - recurrence disease

16
Q

What needs to be done ahead of radio-iodine treatment

A

Stop Breast-feeding ≥ 8 weeks before RAI and do not resume
Sperm banking – esp if likely to have 2+ high dose RAI
Low-iodine diet (<50mcg/day) for 2 weeks before RAI
Avoid sea-food, iodised salt & ‘red’ food colouring. Eggs, butter & cheese
No iodine IV contrast for 8 weeks before treatment
No Amiodarone for a year prior to RAI

17
Q

What precautions need to be taken after RAI?

A

Pt
Avoid constipation – to reduce bowel dose
Drink fluids, suck sweets (dry mouth) – to reduce bladder and salivary gland dose

Others
Visitors – none <16 years, max. 20-60 mins at distance
No close contact with pregnant women or children for up to 3 weeks
Sleep alone for one week
No public transport /crowded places

Double flush toilet for 1 week
Avoid incontinence pads / store for time
Pregnancy
Avoid pregnancy for 6 months after or fathering a child for 4 months
Increased risk miscarriage within 1yr

18
Q

What are the side effects of RAI?

A

Acute
Discomfort / swelling over neck and salivary glands (sialadenitis)
Fatigue
Nausea
Change in taste
Cystitis / gastritis

Late
Dry mouth (RI goes to salivary gland)
Sialoadenitis and lacrimal gland dysfunction
Radiation lung fibrosis – if lots of lung mets
2nd malignancy (0.5%)
Risk is highest with high cumulative dose – e.g. >18.5GBq
Leukaemia, Salivary gland, Breast, Bladder, Colon
Reduce Male Fertility – if ≥2 high dose I131 treatments.
Women unaffected (dose <6Gy) but pt mustn’t be pregnant at time of treatment and shouldn’t become pregnant for 6mths (men shouldn’t father a child for 6wks)

19
Q

What are the outcomes of a dynamic risk stratification?

A

USS & Thyroglobulin

Low risk - If Suppressed & Stimulated Tg <1 & US neck normal:
Aim TSH 0.3 - 2

Int risk - Tg 0.2-1 and sTg 1-10, Neck US: non-specific changes or Stable LN <1cm:
Aim TSH 0.1- 0.5 for 5-10 years

High risk - Suppressed Tg >1 or Stimulated Tg >10, rising Tg, residual disease on imaging:
Aim TSH <0.1

20
Q

What are the indications for EBRT to the thyroid

A

Following RAI / Non-iodine-avid disease

Macroscopic disease after surgery
Recurrent neck disease not amenable to surgery
Palliation of metastases

21
Q

What is the treatment for metastatic thyroid cancer

A

Surveillance & TSH suppression
RAI following total thyroidectomy - likely 5.5Gq dose
Systemic treatment with TKI - lenvatinib

22
Q

What are the side effects of lenvatinib

A

Htn (Aim <140/90), proteinuria, Long QT - monitor
Skin toxicity and palmar-plantar syndrome

23
Q

When is a neck dissection indicated in the management of thyroid cancer

A

Level VI neck dissection if node positive

Prophylactic level VI/VII neck dissection – consider if node neg, but high risk features
Age>55
Tumours >4cm (T3)
Extra-thyroidal disease

24
Q

What must be done before surgery in medullary thyroid cancer

A

Exclude phaeochromocytoma - 24hr urine catecholamines and metanephrines, and plasma metanephrines

25
Q

What is the management of medullary thyroid cancer

A

≤2cm -> Total thyroidectomy + central node dissection
If central nodes +ve -> ipsilateral lateral ND
If lateral nodes +ve -> selective ND (II-V)

> 2cm -> Total thyroidectomy + central ND + prophylactic bilateral selective ND II-V

26
Q

When is EBRT indicated for medullary thyroid cancer

A

Primary RT - if inoperable disease

Adjuvant RT - Locally advanced disease, multiple involved LNs, or raised calcitonin post op indicative of residual disease

27
Q

What is the treatment for metastatic medullary thyroid cancer

A

Assess for RET mutation
Thyroidectomy and further surgery as needed

TKI - cabozantinib (SE - risk of fistulation), selpercatinib 2nd line if RET mutation

28
Q

What mutation should be tested for in anaplastic thyroid cancer

What is the treatment

A

B-raf V600E

Surgical resection

Palliative RT: AP POP: 40Gy in 20# or 20Gy in 5#

Dab/tram if B-raf mut

If early (stage 4A) - can be treated with surgery and adjuvant ChemoRT (H&N fractionation)

29
Q

What proportion of hyper-PTHism is due to parathyroid carcinoma

A

1-2%

30
Q

What gene is associated with parathyroid carcinoma

A

HRPT2 (CDC73)

31
Q

What defines a T3 thyroid cancer

A

> 4cm & limited to thyroid (T3a) or locally invasive into strap muscles (T3b)

32
Q

What thyroid cancer is most likely following radiation exposure

A

Papillary

33
Q
A