JC39 (Surgery) - Thyroid mass Flashcards
List all ddx of goitre
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)
List major histological types of thyroid carcinoma
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
Define simple goiter
List 5 histological subtypes
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
2 most common differentiated thyroid carcinoma
Papillary CA (75%) Follicular CA (10%)
Papillary CA
- Specific risk factors
- Cell origin
- Histology
- Number of nodules
- Route of spread
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
Follicular CA
- Specific risk factors
- Cell origin
- Histology
- Number of nodules
- Route of spread
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
6 “P” Mnemonic for papillary CA of thyroid
Popular (most common) Palpable LNs Positive 131I uptake Positive prognosis Post-op 131I to guide treatment Psammoma bodies
4 “F” Mnemonic for Follicular CA of thyroid
Female predilection (3:1)
Far away metastasis (lungs, bones)
FNAC cannot diagnose
Favourable prognosis
Medullary CA
- Cell origin
- Specific Marker
- Specific risk factor
- Number of nodules
- Mode of spread
- Histology
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
Anaplastic CA
- Cell origin
- Specific RF
- Number of nodules
- Spread
- Histological features
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
S/S of thyroid cancer
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
List 4 risk stratification systems for thyroid CA
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
Outline investigations for thyroid nodule: biochemical, radiological and histological
- 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 - 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 - Histological:
Thyroidectomy for biopsy
Thyroid mass characteristics that suggest malignancy
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)
Ultrasound evaluation of thyroid mass
- Mode
- Advantage
- Disadvantage
- Indication
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
Patient risk factors of malignant thyroid mass
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
Outline T staging of TNM staging for thyroid cancer (AJCC UICC)
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
Outline the N and M staging of TNM staging for thyroid cancer
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
Ddx midline neck mass
Thyroid nodule (isthmus) Thyroglossal cyst Dermoid cyst Ranula Level I lymph node
Ddx anterior neck mass
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
Ddx posterior neck mass
Schwannoma
Cystic hygroma
Cervical rib
Level V lymph node (from NPC)
Ddx supraclavicular neck mass
Supraclavicular lymph node
• Malignancy metastasize from below the clavicle such as gastrointestinal, lung and gynaecological sources
Differentiate reactive, infective, lymphoma and malignant LN on P/E
- 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
Ultrasound features of low-risk vs high-risk thyroid cancer
Outline the Bethesda classification for thyroid mass
Indications for performing FNAC after US exam of thyroid mass
Why is core needle biopsy of thyroid mass not performed?
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
Indications of FNAC for thyroid mass Dx
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
Thyroid scintigraphy
- Function
- Isotopes
- Results (hot vs cold?)
- Disadvantages
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
ATA guideline on USG evaluation and FNAC criteria for Thyroid mass
Indications of surgery for benign thyroid nodules/ nodular goiter
- Pressure symptoms
- Rapid increasing size
- Retrosternal extension
- Suspected malignancy/ malignant potential
- Cosmetics and patient wish
Surgical Treatment options for benign thyroid nodules (2)
Indication, risks, advantages
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
Non-surgical treatment options for benign thyroid nodule
- Types
- Indication
- Advantages and disadvantages
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
Surgical Tx plan for Papillary CA of thyroid
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
Surgical Tx plan for Follicular thyroid CA
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
Surgical Tx plan for Medullary thyroid CA
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
Surgical Tx plan for Anaplastic thyroid CA
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
Pre-operative preparation before thyroidectomy
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
Compare total thyroidectomy vs hemithyroidectomy
- Risk of recurrence
- Risk of hypoparathyroidism
- Risk of RLN palsy
Compare post-op management plan after hemithyroidectomy vs total thyroidectomy
Total thyroidectomy needs:
- RAI scan for recurrence
- Adjuvant RAI ablation for residual tumor
- Lifelong T4 replacement
- Thyroglobulin monitoring for recurrence
None for hemithyroidectomy
Outline 3 techniques of LN dissection for thyroid cancer
Advantage and disadvantage of cervical LN dissection for thyroid cancer
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
Induction of radioactive Iodine uptake in thyroid cancer (check)
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
Indication for post-operative radioactive Iodine
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
Papillary thyroid microcarcinoma
- Typical TNM stage
- Risk
- Prognosis
- Treatment
Typical:
< 1cm and incidentally detected, Stage I
Risk: Extremely low, rare metastasis
Prognosis: Excellent survival
Treatment: Active observation after biopsy confirmation
