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MBBS IV - Junior Clerkship WCS > JC39 (Surgery) - Thyroid mass > Flashcards

JC39 (Surgery) - Thyroid mass Flashcards

1
Q

List all ddx of goitre

A

1) Simple goiter (endemic or sporadic) (70%)
- Diffuse
- Nodular

2) Neoplastic goiter (25%)
- Benign
- Malignant

3) Toxic goiter
- Diffuse toxic (Grave’s)
- Nodular toxic (Plummer’s)
- Toxic/ Functional adenoma

4) Thyroiditis
- Bacterial/ suppurative (acute)
- Viral (subacute)
- Lymphocytic/ Autoimmune (chronic)

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2
Q

List major histological types of thyroid carcinoma

A

1) Thyroid follicular epithelium-derived
a) Differentiated tumour:
o Papillary carcinoma (80 -90%)
o Follicular carcinoma (5 – 10%)
b) Undifferentiated tumour: Anaplastic carcinoma (5 – 10%)

2) Parafollicular cells (C-cells)-derived (produces calcitonin) Neuroendocrine tumour
o Medullary carcinoma (< 10%)

3) Other malignancy
• Lymphoma (1 – 2%)
• Sarcoma
• Metastatic cancer

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3
Q

Define simple goiter

List 5 histological subtypes

A

Any thyroid enlargement
Not due to neoplasia or inflammation
No thyroid dysfunction
Can be uninodular or multinodular

Colloid 
Haemorrhagic cystic 
Complex 
Hyperplastic 
Adenomatous

Adenomatous, hyperplastic, colloid polyps are multifocal

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4
Q

2 most common differentiated thyroid carcinoma

A 
Papillary CA (75%)
Follicular CA (10%)
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5
Q

Papillary CA

  • Specific risk factors
  • Cell origin
  • Histology
  • Number of nodules
  • Route of spread
A

RF: Radiation exposure, FAP, Gardner’s syndrome

Origin: Thyroid follicular epithelium, differentiated tumor

Histology: Orphan Annie eye nuclei, nuclear pseudoinclusions, papillary architecture, Psammoma bodies (microcalcs on USG),
tall cell variant (a/w poorer prognosis)

Number: Multifocal, Unilateral

Spread: Local or Lymphatics (Level VI LN first), hematogenous rarely

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6
Q

Follicular CA

  • Specific risk factors
  • Cell origin
  • Histology
  • Number of nodules
  • Route of spread
A

RF: Multinodular goitre

Cell: Thyroid follicular epithelium, differentiated tumor

Histology: capsular/vascular invasion cf follicular adenoma, Hurthle cell variant (a/w poorer prx)

Number: Solitary, Unilateral

Spread: haematogenous predilection
→ liver, lung, bone, brain

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7
Q

6 “P” Mnemonic for papillary CA of thyroid

A 
Popular (most common)
Palpable LNs
Positive 131I uptake
Positive prognosis
Post-op 131I to guide treatment
Psammoma bodies
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8
Q

4 “F” Mnemonic for Follicular CA of thyroid

A

Female predilection (3:1)
Far away metastasis (lungs, bones)
FNAC cannot diagnose
Favourable prognosis

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9
Q

Medullary CA

  • Cell origin
  • Specific Marker
  • Specific risk factor
  • Number of nodules
  • Mode of spread
  • Histology
A

Cell: Parafollicular cell (C-cell) derived, neuroendocrine tumor

Marker: CALCITONIN + CEA

RF: MEN2 syndrome, Familial MTC

Number: Multifocal, bilateral

Mode: Local, Lymphatics (70%)

Histology: Acellular amyloid deposit, multicentric C-cell hyperplasia

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10
Q

Anaplastic CA

  • Cell origin
  • Specific RF
  • Number of nodules
  • Spread
  • Histological features
A

Cell: thyroid follicular epithelium, Undifferentiated tumor

RF: Previous differentiated thyroid carcinoma

Number: Solitary, Unilateral

Spread: Local (main), hematogenous, lymphatic

Histological: Small blue round anaplastic cells

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11
Q

S/S of thyroid cancer

A

Thyroid nodule and neck swelling - Discomfort mainly (pain due to sudden increased mass in inflammation or hemorrhage)

Thyroid dysfunction - Hyper- or hypothyroidism

Local pressure symptoms - Dysphagia/ choking/ aspiration; SOB/ cough/ sputum; Hoarseness/ vocal cord paralysis/ stridor

SVC obstruction - retrosternal extension

Cervical lymphadenopathy

Distant metastatic symptoms (e.g. pleural effusion, neurological signs, bone pain…etc)

Constitutional symptoms

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12
Q

List 4 risk stratification systems for thyroid CA

A

TNM staging: predicts disease-specific mortality

MACIS system: predicts disease-specific mortality

AMES risk stratification: predicts disease-specific mortality
→ Age >45y, Metastasis, Extrathyroid extension, Size >4cm

ATA risk stratification: predicts disease recurrence risk

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13
Q

Outline investigations for thyroid nodule: biochemical, radiological and histological

A
  1. Biochemical:
    - CBC with differentials
    - Serum Ca and PO4
    - TFT: Serum TSH and fT3, fT4
    - Thyroid autoantibodies: Anti-thyroglobulin (recurrence after total resection)
    - Serum thyroglobulin (marker for differentiated tumor)
    - Serum calcitonin (marker for differentiated tumor, medullary carcinoma)
    - Serum CEA (marker for differentiated tumor, medullar carcinoma)
    - Genetic test: RET mutation in MEN2, TSH receptor mRNA RT-PCR
  2. Radiological:
    - Ultrasound of neck
    - FNAC
    - Thyroid Radioscintigraphy
    - CXR: Tracheal deviation, retrosternal extention
    - CT thorax: retrosternal extension, local invasion
    - Bronchoscopy and OGD: upper aerodigestive tract invasion
    - PET/CT, CT/MRI for distant metastasis
  3. Histological:
    Thyroidectomy for biopsy
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14
Q

Thyroid mass characteristics that suggest malignancy

A

Mass factors:

  • Solitary or multiple nodules (solitary more likely malignant)
  • Nodule characteristics (size, consistency, fixation)
  • Cervical LN enlargement
  • RLN palsy
  • Distant metastatic symptoms (e.g. pleural effusion, bone pain…etc)
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15
Q

Ultrasound evaluation of thyroid mass

  • Mode
  • Advantage
  • Disadvantage
  • Indication
A

Mode: B-mode real-time scanner at 10mHz probe

Advantage:

  • Non-invasive
  • No radiation
  • Convenient and cheap

Disadvantage:

  • High sensitivity but low specificity, cannot confirm Dx
  • Operator dependent

Indication:

  • All patients with goiter/ palpable nodule
  • Guide needle aspiration
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16
Q

Patient risk factors of malignant thyroid mass

A

Female sex

Middle age

Family history: Thyroid cancer, FAP (Papillary carcinoma), MEN2 (medullary carcinoma), Gardner’s syndrome

Head and neck irradiation: childhood leukaemia, bone marrow transplant, environmental radiation

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17
Q

Outline T staging of TNM staging for thyroid cancer (AJCC UICC)

A

TX: Primary tumour cannot be assessed
T0: No evidence of primary tumour

T1: ≤ 2 cm in greatest dimension limited to thyroid

T2: > 2 cm but ≤ 4 cm in greatest dimension limited to thyroid

T3: > 4 cm in greatest dimension limited to thyroid OR gross extrathyroid extension invading only strap muscles

T4: gross extrathyroidal extension to subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve; prevertebral fascia or encases carotid artery or mediastinal vessels

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18
Q

Outline the N and M staging of TNM staging for thyroid cancer

A

N0 - No met/ histologically confirmed benign LN

N1 - Regional LN metastasis to Level VI or VII; metastasis to Level I-V; metastasis to retropharyngeal LN

M0 - No distant met.
M1 - Distant met. present

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19
Q

Ddx midline neck mass

A 
 Thyroid nodule (isthmus)
 Thyroglossal cyst
 Dermoid cyst
 Ranula
 Level I lymph node
20
Q

Ddx anterior neck mass

A

Cysts and nodules:
 Thyroid nodules, thyroglossal cyst
 Branchial cleft cyst
 Laryngocele

Carotid artery:
 Carotid body tumour (Chemodectoma)
 Carotid artery aneurysm

 Submandibular gland mass

 Level II – IV lymph node enlargement

21
Q

Ddx posterior neck mass

A

 Schwannoma
 Cystic hygroma
 Cervical rib
 Level V lymph node (from NPC)

22
Q

Ddx supraclavicular neck mass

A

Supraclavicular lymph node

• Malignancy metastasize from below the clavicle such as gastrointestinal, lung and gynaecological sources

23
Q

Differentiate reactive, infective, lymphoma and malignant LN on P/E

A
  • Discrete, mobile, firm or rubbery but not rocky hard, slightly tender = Reactive LN
  • Isolated, asymmetric, tender, warm and erythematous, fluctuant = Infected LN
  • Firm, rubbery, rapidly expanding = Rapidly growing lymphoma
  • Rock-hard, fixed (invasion through capsule and fixed to underlying structures) and non-tender = Malignancy
24
Q

Ultrasound features of low-risk vs high-risk thyroid cancer

A
25
Q

Outline the Bethesda classification for thyroid mass

A
26
Q

Indications for performing FNAC after US exam of thyroid mass

A
27
Q

Why is core needle biopsy of thyroid mass not performed?

A

Core needle biopsy is NOT performed
o Lead to massive bleeding since thyroid is a very vascularized structure
o FNAC is very accurate in identifying type of thyroid cancer

28
Q

Indications of FNAC for thyroid mass Dx

A

Indications
o Sonographic criteria for FNA
o Hypofunctioning (cold) nodules in thyroid scintigraphy
o Dominant or atypical nodule in multinodular goitre
o Nodules associated with abnormal LN
o Complex or recurrent cystic nodules

29
Q

Thyroid scintigraphy

  • Function
  • Isotopes
  • Results (hot vs cold?)
  • Disadvantages
A

Function:
• Functional assessment of thyroid nodule
• Combined with LOW Serum TSH level indicates overt or subclinical hyperthyroidism which increases the possibility that a thyroid nodule is hyperfunctioning

Isotopes:
- IV radioisotope I-123 or Tc-99m

Results:

  • Hyperfunctioning (hot) nodules (uptake is greater than surrounding thyroid tissues) are rarely cancer and hence does NOT require FNA
  • Hypofunctioning (cold) nodules (uptake is less than surrounding thyroid tissues) has 10 – 20% of being cancer and hence requires FNA provided that sonographic criteria are met

Disadvantage:
Expensive, radiation, low specificity and sensitivity

30
Q

ATA guideline on USG evaluation and FNAC criteria for Thyroid mass

A
31
Q

Indications of surgery for benign thyroid nodules/ nodular goiter

A
  1. Pressure symptoms
  2. Rapid increasing size
  3. Retrosternal extension
  4. Suspected malignancy/ malignant potential
  5. Cosmetics and patient wish
32
Q

Surgical Treatment options for benign thyroid nodules (2)

Indication, risks, advantages

A

Hemithyroidectomy

  • Indication: uninodular goiter
  • Risks: Low chance of hypothyroidism, safe, minimal morbidities
  • Advantage: easy to re-operate on contralateral lobe in Completion Total Thyroidectomy

Bilateral Thyroidectomy

  • Indication: Multinodular goiter
  • Risks: Surgical risk, hypoparathyroidism, long-term thyroxine
  • Advantage: No recurrence
33
Q

Non-surgical treatment options for benign thyroid nodule

  • Types
  • Indication
  • Advantages and disadvantages
A

Types:

1) Ethanol injection (PEI)
2) HIFU
3) Radiofrequency ablation (RFA)
4) Percutaneous laser ablation (LA)
5) Microwave ablation (MWA)

Indications:
- Patient factors: symptomatic, single hyperfunctional nodule with growth, histologically benign on 2 FNAC

Advantage:
- Preserve function, minimal invasive, better cosmetics, no GA

Disadvantage:
- Fail to cure, regrowth, risk of ablation, expensive, long follow-up procedures

34
Q

Surgical Tx plan for Papillary CA of thyroid

A 
Hemithyroidectomy (1-4cm without extra-thyroidal extension)
Total thyroidectomy (>4cm with extra-thyroid extension and metastasis)

LN dissection:

  • Central compartment (Level VI) dissection as prophylaxis (high risk tumor) or therapeutic
  • Lateral compartment dissection for therapeutic removal
35
Q

Surgical Tx plan for Follicular thyroid CA

A

Hemithyroidectomy first after FNAC
Completion thyroidectomy for follicular carcinoma

LN dissection:

  • Central compartment (Level VI) dissection as prophylaxis (high risk tumor) or therapeutic
  • Lateral compartment dissection for therapeutic removal
36
Q

Surgical Tx plan for Medullary thyroid CA

A

ALL patients undergo Total Thyroidectomy (high risk, aggressive tumor, prone to metastasis)

LN dissection:

  • Central compartment (Level VI) dissection as prophylaxis for ALL patients
  • Lateral compartment dissection for therapeutic removal
37
Q

Surgical Tx plan for Anaplastic thyroid CA

A

Total thyroidectomy with post-operative chemotherapy/ combined chemo and radiotherapy

Chemotherapy or Radiotherapy with External Beam Radiotherapy (EBRT) for surgically inoperable tumor

Tracheostomy for upper airway obstruction

38
Q

Pre-operative preparation before thyroidectomy

A

 Anti-thyroid drugs or β-blockers
• Prevention of thyroid storm

 Calcium supplements and vitamin D
• Prevention of postoperative hypocalcemia
• Prevention of hungry bone syndrome (HBS)

 Lugol’s solution
• Block iodine uptake and secretion of thyroid hormone
• Decrease vascularity of thyroid gland to reduce intraoperative bleeding

39
Q

Compare total thyroidectomy vs hemithyroidectomy

  • Risk of recurrence
  • Risk of hypoparathyroidism
  • Risk of RLN palsy
A
40
Q

Compare post-op management plan after hemithyroidectomy vs total thyroidectomy

A

Total thyroidectomy needs:

  • RAI scan for recurrence
  • Adjuvant RAI ablation for residual tumor
  • Lifelong T4 replacement
  • Thyroglobulin monitoring for recurrence

None for hemithyroidectomy

41
Q

Outline 3 techniques of LN dissection for thyroid cancer

A
42
Q

Advantage and disadvantage of cervical LN dissection for thyroid cancer

A

Advantages:

  • Lower recurrence rate
  • Prevent mircometastasis

Disadvantage:

  • Detection of LN micrometastasis may lead to upstaging of disease
  • Risk of damaging parathyroid gland
  • Cosmetic: Lateral LN dissection require separate incision and scar
43
Q

Induction of radioactive Iodine uptake in thyroid cancer (check)

A

Thyroxine withdrawal for 4 weeks to induce hypothyroidism and increase TSH uptake

Give Thyrogen (synthetic TSH) 1-2 days before operation to increase radioactive iodine uptake

44
Q

Indication for post-operative radioactive Iodine

A

Stage I and II, Low risk tumor:

  • RAI for short-term ablation of occult microscopic tumor foci
  • Use for disease surveillance and recurrence

Stage III and IV, High risk tumor:

  • RAI for longer therapy to clear persistent/ residual tumor
  • RAI to clear nodal or distal metastasis
45
Q

Papillary thyroid microcarcinoma

  • Typical TNM stage
  • Risk
  • Prognosis
  • Treatment
A

Typical:
< 1cm and incidentally detected, Stage I

Risk: Extremely low, rare metastasis

Prognosis: Excellent survival

Treatment: Active observation after biopsy confirmation

MBBS IV - Junior Clerkship WCS (131 decks)

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