Thyroid nodules Flashcards
When should thyroid nodules be evaluated for malignancy?
- Solid nodules ≥ 10 mm size
- Spongy nodules ≥ 20 mm size
- Suspicious ultrasound features
• Hypoechoic, microcalcification, increased vascularity, infiltrative margins, absent halo, taller than wide - Family history of thyroid cancer
- History of head & neck irradiation or exposure to ionizing radiation (especially as a child or adolescent)
- Rapid growth of nodule, hoarseness, associated lymphadenopathy
How can you evaluate thyroid nodules for malignancy?
Ultrasound-guided FNA
It produces lower rates of nondiagnostic and false-negative cytology
What are the suspicious ultrasound features of thyroid nodule?
Hypoechoic, microcalcification
Increased vascularity, infiltrative margins, absent halo, taller than wide
What classification do you use for thyroid FNA results and what are the 6 major categories?
Bethesda Classification: 6 major categories of results that are obtained from FNA
- Non-diagnostic
- Benign
- Follicular lesion or atypia of undetermined significance (5-10% malignant)
- Follicular neoplasm (20-30% malignant)
- Suspicious for malignancy (50-75% risk of malignancy)
- Malignant
What are the categories of thyroid FNA results and How is your management different according to FNA result of the thyroid nodule?
- Non-diagnostic -> repeat (US-FNA)
- Benign (macrofollicular) -> follow up with US in 6-12 months
- Follicular lesion/atypia of undetermined significance -> repeat FNA after 3-6 months
- Follicular neoplasm (microfollicular): check TSH, thyroid stratigraphy etc. Diagnostic hemithyroidectomy.
- suspicious for malignancy -> surgery
- Malignant -> surgery
What would you see microscopically in a thyroid papillary carcinoma?
- enlarged atypical epithelial cells with oval nuclei and moderate amounts of pale cytoplasm.
- Numerous papillary structures with fibrovascular cores
- Frequent nuclear grooves and intranuclear cytoplasmic pseudoinclusions
What is the indication for total thyroidectomy?
For thyroid cancer >1 cm, the initial surgical procedure should be total thyroidectomy.
What are the arguments FOR total thyroidectomy in thyroid cancer?
- PTC (papillary thyroid cancer) is often multifocal and bilateral
- Radioactive iodine ablation of thyroid bed remnant and treatment of metastatic disease is facilitated by resection of as much thyroid tissue as possible
- Measurements of serum thyroglobulin as a tumour marker is facilitated by removal of nearly all normal thyroid tissue
- Prevention of recurrence in the contralateral lobe
- Avoids ultrasound identified nonspecific abnormalities in the remaining contralateral lobe during follow-up that is a source of concern to both the clinician and the patient
What are the arguments AGAINST total thyroidectomy in thyroid cancer?
- Absence of a survival benefit with more extensive surgery
* Fewer complications with unilateral surgery
What is the indication for therapeutic & prophylactic lymph node dissection in thyroid cancer?
Therapeutic central neck dissection:
- clinically involved central or lateral lymph nodes along with total thyroidectomy
Prophylactic central neck dissection:
- PTC with clinically uninvolved central neck lymph nodes, especially for advanced tumours (≥4 cm)
What is the indication for therapeutic lateral neck compartmental dissection in thyroid cancer?
biopsy-proven metastatic lateral cervical lymphadenopathy
When is total thyroidectomy without prophylactic central neck dissection appropriate?
small (less than 4cm), non invasvie, clinically node-negative PTCs and most follicular cancer
Which adjunctive treatments are frequently used following surgery for thyroid cancer?
1.Radioactive iodine remnant ablation
•Recombinant human TSH (Thyrogen)
•Thyroxine withdrawal
2.Thyroid hormone suppression therapy
•TSH
How do you Follow-Up of Patients With Thyroid Cancer Based on Risk Stratification Long-Term?
- Clinical examination every 12 months
- Thyroid bed/neck ultrasound at one year, then frequency based on risk
- Serum thyroglobulin estimation every 12 months
- Thyroglobulin antibodies should be quantitatively assessed with every measurement of serum thyroglobulin
How should multinodular goitres be evaluated for malignancy?
- preferential FNA for suspicious sonographic nodes
- if non suspicious sonographically & multiple sonographically similar nodules, low risk of malignancy -> aspirate the largest & observe others with serial US
- Radionuclide scanning for multiple nodules -> FNA the hypofunctioning nodules
What is the microscopic appearance of a colloid nodule?
abundant colloid and scant follicular cells
The cells are grouped into follicles
small cells and uniform with a central nucleus
NB: colloid nodules are benign
What are the Indications for Surgery in Multinodular Goitre?
- Evidence of malignancy
- Increasing size of dominant nodule(s)
- Symptomatic – pressure symptoms, hoarseness
- Retrosternal extension
How do you follow up pts with multinodular goitre?
- annual clinical exam & serial US
- nodules increasing in size (>50% volume or >20% increase in >2 nodule dimensions) should have repeat FNA
- if stable for 12-24 months, longer interval b/w exam & US
DDx of thyrotoxicosis + singe nodule
- thyroid nodule autonomously producing thyroid hormone (toxic nodule)
- Graves disease with an incidental nodule
- Subacute thyroiditis: Px with neck pain/general malaise
What are 3 Rx options for a toxic thyroid nodule?
- Anti-thyroid drug treatment
- Surgery
- Radioactive Iodine (I131) treatment (most recommended)
What are the advantages and disadvantages of anti-thyroid drug treatment?
Advantages:
•Useful as a short term measure
•Will rapidly correct thyroid function and alleviate symptoms
•Can be used prior to surgery to ensure patient is euthyroid and fit for surgery.
•Can be used prior to I131 treatment if patientis very symptomatic.
Disadvantages:
•Will not effect a permanent “cure”
•Possible side effects: rash – common (5%), agranulocytosis – rare, abnormal LFT’s – PTU only.
Name 2 examples of anti-thyroid drug
Carbimazole
Propylthiouracil (PTU)
What are the advantages and disadvantages of toxic thyroid nodule surgery?
Advantages:
•Rapid total cure
•Targeted minimally invasive surgery
•Very low risk of hypothyroidism
Disadvantages:
•Surgical risk
•Scar
•Specific risks of thyroid surgery: damage to recurrent laryngeal nerve, hypoparathyroidism (very unlikely with unilateral surgery)
What are the advantages and disadvantages of radioactive iodine treatment?
Advantages:
•High chance of total cure
•One single oral administration
•Essentially non-invasive
Disadvantages:
•Possibility of long term hypothyroidism
•slow onset (4wk-6months)
•Imprecise dosing: a second dose may be required if initial dose is insufficient.
•C/I: pregnancy, wishing to conceive soon.
•Must stay away from children for 2-3 weeks (radiation)
What is a reasonable approach to follow up after radioactive iodine treatment?
check TFT’s in 3 months, and if normal 6 months later, and then annually
Slightly high TSH, T4 but normal T3. What can you make out of this? What further Ix would you do?
Hypothyroid -> high TSH
But T4 is also up at the same time.
Wait 6 weeks and repeat the TFT.
When you order TFT, what should you also look for in hypo & hyper?
Hypo:
- anti-thyroglobulin antibodies
- anti-thyroid peroxidase antibodies (Anti-TPO)
Hyper:
- anti TSH receptor (Grave’s)
What is the investigation of choice in thyroid nodule?
FNA (mostly under US control)
Perhaps even better than core biopsy
When (6) would you decide to do a FNA on thyroid nodule?
1. solid nodules >10mm 2 Spongy nodules >20mm 3. Suspicious US features - microcalficiations - irregular margins - hypoechoic - posterior shadowing - increased blood flow on Doppler
- FMHx of thyroid cancer
- Hx of head & neck irradiation or exposure to ionising radiation (esp as a child)
- Rapid growth of nodule, hoarseness, associated lymphadenopathy
What is the main type of differentiating thyroid cancers?
Papillary thyroid cancer (80%)
in young people
Which thyroid cancer is associated with irradiation?
Papillary cancer
Why can thyroid cancer present with hoarse voice?
The cancer can affect recurrent laryngeal nerve
What lymph nodes should you consider in thyroid malignancy? Ix?
Central/paratracheal lymph nodes (C6)
Lateral lymph nodes
FNA of lymph node -> see if the cells are from thyroid malignancy.
SE of contrast (radioactive iodine) in thyroid Ix?
- Can precipitate hyperthyroidism in Goitre
- Radioactive iodine after surgery for months
What can you use as a tumour marker for thyroid cancer to check after total thyroidectomy?
Serum thyroglobulin
What levels are central/lateral lymph nodes at in the neck?
6, 7: central lymph nodes
2, 3, 4: lateral lymph nodes
(3) SE of longterm thyroid hormone suppression therapy/radioactive iodine remnant ablation
- Proximal myopathy
- osteoporosis
- arrhythmias/AF
Prognosis of differentiated thyroid cancer
98% at 20 year survival
DDx of hyperthyroid + solitary nodule in mid part of left lobe found on ultrasound.
- Single toxic nodule
- Grave’s disease (diffuse)
Difference b/w single toxic nodule & Grave’s disease on nuclear thyroid scan
Single toxic nodule: hot on the spot & cold in the rest (it takes all the iodine to it)
Grave’s disease: hot diffusely overall.
