How do you follow a thyroid nodule that has a benign FNA biopsy.
1) The false-negative rate of FNA biopsy is about 5%
2) Nodule growth alone is not an indication of malignancy, but growth is an indication for repeat FNA biopsy
3) ATA guidelines recommend serial clinical exam for easily palpable nodules at 6-18 month intervals
4) All other benign nodules should be followed with serial U/S examinations 6-18 months after initial FNA bx
- Pts with nodules that are stable at this f/u U/S may have subsequent examinations at longer time intervals
- Pts with evidence of nodule growth should have a repeat FNA bx, preferably with U/S guidance
Diagnostic algorithm for evaluation of thyroid nodules
2017 Bethesda System for Reporting Thyroid Cytopathology and Implied Risk of Malignancy - Treatment Algorithm
I. Bethesda Category I - Non Diagnostic or Unsatisfactory
1. Risk of Malignancy if NIFTP does not = CA : 5-10%
2. ROM if NIFTP = CA: 5-10%
3. Usual Management: Repeat FNA bx with U/S guidance
II. Bethesda Category II - Benign
1. Risk of Malignancy if NIFTP not = CA: 0-3%
2. ROM if NIFTP = CA: 0-3%
3. Usual Management: Clinical and U/S f/u
III. Bethesda Category III - Atypical of Undetermined Significance (AUS) or Follicular Lesion of Undetermined Significance (FLUS)
1. ROM if NIFTP not = CA: 6-18%
2. ROM if NIFTP = CA: 10-30%
3. Usual Management: Repeat FNA, Molecular Testing, or Lobectomy
IV. Bethesda Category IV - Follicular Neoplasm (FN) or Suspicious for Follicular Neoplasm (SFN)
1. ROM if NIFTP not = CA: 10-40%
2. ROM if NIFTP = CA: 25-40%
3. Usual Management: Molecular Testing, Lobectomy
V. Bethesda Category V - Suspicious for Malignancy
1. ROM if NIFTP not = CA: 45-60%
2. ROM if NIFTP = CA: 50-75%
3. Usual Management: Near Total Thyroidectomy or Lobectomy
VI. Bethesda Category VI - Malignant
1. ROM if NIFTP not = CA: 94-96%
2. ROM if NIFTP = CA: 97-99%
3. Usual Management: Near Total Thyroidectomy or Lobectomy
How should you approach/evaluate a PET-avid thyroid nodule?
FNA biopsy is recommended for any PET-avid nodule > 1cm
What are the American College of Radiology (ACR) guidelines for evaluation of incidentally found thyroid nodules?
I. You should obtain a dedicated U/S only for:
1) Patients 35 years old or older with nodules >/= 1.5cm in size
2) In patients </= 35 with nodules >/= 1.0cm in size
II. FNA biopsy should be obtained for incidentally found thyroid nodules based on risk stratification based on:
1) Size of the nodule
2) Radiographic U/S features
3) Clinical risk factors
What are the U/S features of a thyroid nodule that are correlated with thyroid cancer?
1) Macrocalcifications
2) Irregular margins
3) Taller than wide shape
4) Hypoechoic and solid nodules are higher risk for malignancy
5) Spongiform nodules - nodules with > 50% small multicystic composition have an extremely low likelihood of malignancy
- FNA biopsy is recommended if these nodules are > 2cm diameter
6) Purely cystic thyroid nodules are benign - no diagnostic evaluation is required.
What size of thyroid nodule should be evaluated with FNA biopsy?
Generally, only thyroid nodules > 1cm diameter will require evaluation due to the greater likelihood of clinical significance.
What is a papillary thyroid microcarcinoma and what is its clinical significance?
A malignant Papillary Thyroid Microcarcinoma (PTMC) is a Papillary Carcinoma that is less than 1cm in diameter.
1) They have an extremely low locoregional recurrence rate (2% to 6%)
2) The disease specific mortality rate for PTMC is < 1%
3) Nodules > 2cm show higher rates of distant mets for PTC and FTC histologies
4) There is a 99.4% 10 year relative survival rate for patients with thyroid cancers < 3cm
What is the relationship between thyroid nodule growth rates and malignancy?
I. Malignant thyroid nodules are more likely to grow > 2mm/year compared to benign thyroid nodules
II. The current ATA guidelines on growth of a nodule:
1) When growth of a thyroid nodule [> 20% growth in two dimensions and a minimal increase of 2mm, or (>/=) 50% increase in volume] is detected during U/S surveillance, consider one of the following interventions:
- Shorter interval observation
- Repeat FNA biopsy
- Diagnostic lobectomy
III. Although nodule growth should be considered, malignancy in nodules that are followed is better predicted by changes in sonographic appearance than in growth patterns
What is the cancer risk associated with multinodular goiter?
I. Each nodule > 1cm carries an independent risk of malignancy
II. MNG does not predict a lower risk of malignancy
III. The risk of malignancy per patient is similar whether a single nodule or multiple nodules > 1cm are detected
Which nodules withing a Multinodular Goiter (MNG) should be chosen for biopsy?
1) Nodules in a MNG should be chosen for bx based on sonographic appearance and size cutoff.
2) Radionucleotide scan should be performed in patients with suppressed TSH, and only iso- or hypo-functioning nodules should be considered for biopsy.
3) The ACR TI-RADS committee recommends targeting no more than two nodules with the highest suspicion for FNA bx
- Do not use the term ‘dominant nodule (largest).’ The largest nodule in a MNG is malignant 72% of the time.
- Among patients with multiple thyroid nodules > 1cm in diameter who proved to have thyroid CA, the malignancy was located in the largest nodule only 72% of the time.
- The predictive value of largest-nodule aspiration decreased as the quantity of nodules in the gland increased.
What are the radiographic features suggestive of malignancy in lymph nodes?
1) Absence of an echogenic hilum
2) Round shape
3) Cystic component
4) Irregular borders
5) Hyper-echogenicity
6) Peripheral vascularity
Where does regional spread of thyroid cancer occur?
1) Most commonly involves the central neck (level VI)
2) Next most common area is the lateral neck (levels II to IV)
3) The least common area is the posterior neck (level V)
What is the risk of malignancy in a PET-Avid thyroid nodule?
Approximately 25%
How should a ‘Non Diagnostic’ FNA biopsy of a thyroid nodule be managed?
1) Repeat U/S guided FNA bx should be performed
- 50% of such repeat FNA biopsies yield diagnostic information
2) Thyroid lobectomy should be considered for a thyroid nodule with multiple non diagnostic results
- Core needle biopsy may also be considered
3) The risk of malignancy in a ‘Non diagnostic’ thyroid nodule is approximately 10%
4) Nodules that have a highly suspicious appearance on U/S or that demonstrate significant growth on U/S should be considered for thyroid lobectomy
5) Clinical risk factors for malignancy should also be considered in surgical decision making
How should a ‘Benign’ FNA biopsy of a thyroid nodule be managed?
1) Surgery is deferred in lieu of serial U/S surveillance
2) Occasionally, thyroid lobectomy should be considered in the following scenarios:
- When the nodule is greater than 3-4 cm
- With compressive symptoms
- Need for absolute assurance by the patient
What is the overall risk of malignancy in a thyroid nodule?
8% to 15%
What elements of the patient’s history are concerning for thyroid malignancy?
1) H/O childhood irradiation to the head or neck
2) Exposure to radioactive fallout
3) Family h/o thyroid cancer in a first-degree relative
4) Family h/o hereditary syndromes associated with thyroid cancer
- MEN 2 syndrome associated with hereditary medullary thyroid cancer
Note: The strongest risk factors for differentiated thyroid cancer (DTC) are:
1) Family h/o DTC is a known risk factor for thyroid malignancy
2) Prior head and neck radiation exposure
What syndromes are associated with DTC in first degree relatives?
1) Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (Cowden’s disease)
2) Familial adenomatous polyposis (FAP)
3) Carney complex
Should patients be screened for thyroid nodules?
1) For patients who o/w do not have symptoms or risk factors, routine screening for thyroid nodules by neck palpation, neck U/S, or other techniques should not be performed.
2) There is currently no evidence to support reduced mortality or improved quality of life when patients with low-risk thyroid malignancy (most commonly papillary thyroid CA) are treated at an asymptomatic stage.
