Solitary Thyroid Nodule

Question 1

Patient presents with solitary thyroid nodule. What is first line of investigation?

Answer 1

Order serum TSH. If low (meaning hyperthyroid), then do radioisotope scan.

If normal or elevated TSH, do ultrasound and FNAB

Question 2

Based on radioisotope scan results, what would you do next?

Answer 2

Hot nodule- send for surgery or 131-iodine or surgery

Cold nodule- ultrasound and FNAB

Question 3

At what size cut-off would you consider doing an FNAB on a nodule?

Answer 3

1 cm

Question 4

What are the six diagnostic categories on the Bethesda system for reporting cytopathology?

What is the corresponding course of action for each category?

Answer 4

1) Non-diagnostic–> repeat
2) Benign–> follow in 3-6 months if high suspicion

3) AUS/FLUS (atypia of undetermined significance, or follicular lesion of undetermined significance)
called indeterminate
–> repeat or surgery or genetics

4) FN/SFN (follicular neoplasm or suspect follicular neoplasm)
- -> surgery (diagnostic lobectomy usually)

5) suspect malignancy –> surgery
6) malignancy –> surgery

Question 5

What % of population have solitary thyroid nodules?

Of these people what % are malignant?

Answer 5

5 and 5

5% of general population will have thyroid nodule
5% of thyroid nodules are malignant

Question 6

Typical latency period between radiation exposure and clinically evident cancer?

Answer 6

3-8 years

Question 7

What is risk of malignancy with FLUS or AUS category?

Answer 7

5-15% (TO Manual)

Question 8

Indications for resection if you have thyroid nodule?

Answer 8

• Symptomatic- compressive or inflammatory symptoms
• Hyperfunctioning
• Suspicion or malignancy or frank malignancy

Question 9

What to ask on history of patient with thyroid nodule?

Answer 9

HPI:

• duration of nodule
• growth
• compressive or invasive symptoms: dysphonia, dysphagia, choking sensation, dyspnea
• hyperthyroid or hypothyroid symptoms

PMHx: radiation exposure, childhood cancers

Fam Hx: H&N cancers, familial syndromes

Soc Hx: EtOH, smoking

Question 10

Physical exam of thyroid nodule?

Answer 10

• Vitals
• Thyroid exam- inspection, palpation (usually from behind), comment on qualities of nodule- mobile, size, firmness
• Head and Neck exam- feel for lymphadenopathy
• Oral exam- look inside mouth at all mucosal surfaces

Question 11

Risk factors for malignancy in a thyroid nodule?

Answer 11

1) Age- extremes of age are bad (<30 or >60)
2) Male
3) previous radiation exposure

Question 12

What are some worrisome features on ultrasound that nodule may be malignant?

Answer 12

• microcalcifications
• rim calcifications
• taller than wide
• extrathyroidal extension
• irregular borders
• hypervascularity
• hypoechoic
• solid component

Question 13

Difference between hot and cold nodules on 123-iodine scintigraphy (RAI scan).

Answer 13

hot nodules- hyperfunctioning on thyroid scan
elevated uptake throughout enlarged gland
still 5% chance for malignancy

cold nodules

• hypofunctioning
• 15-20% chance of malignancy

Question 14

What is the gold standard for initial evaluation and diagnostic tool for thyroid masses?

Answer 14

Fine needle aspiration biopsy

-determine with 70-90% accuracy whether nodule is benign, malignant or suspicious

Question 15

Describe genetic testing possibilities when you have a Bethesda 3.

Answer 15

mutational analysis- currently looks for 7 gene panel including:

• BRAF, RAS, RET/PTC, PAX8, PPAR/gamma mutations
• low sensitivity, but high specificity
• also 167 GEC available

Other possibilities are: mRNA gene expression classifier, or microRNA gene expression combined with mutational analysis

Question 16

Can you use FNA to diagnose follicular thyroid cancer?

Answer 16

No
based on demonstration of capsular or vascular invasion by follicular cells

FNA can show you cellular features, but does not show tissue architecture