Thyroid Nodules and Cancer

Question 1

What is a toxic thyroid nodule?

Answer 1

An autonomous nodule on the thyroid which doesn’t obey the feedback, just autonomously keeps making excess thyroid hormone

Question 2

What are the three ways to diagnose thyroid nodules?

Answer 2

1) Ultrasound (much better at detecting, more sensitive for smaller nodules) or autopsy
2) Neck doppler - find incidental thyroid lump
3) Palpation - not most sensitive way to exclude thyroid nodule

Question 3

What size are palpable nodules?

Answer 3

> 1 cm (if < 1cm, easy to miss)

Question 4

What % of thyroid nodules are benign?

Answer 4

95% (may be lower)

Question 5

What are risk factors for thyroid nodules?

Answer 5

1) Women

2) Age

Question 6

What should be done if a thyroid lump is detected?

Answer 6

Pt should be referred to clinical to do further imaging to determine if it is benign or malignant (US)

Question 7

What are causes of malignant thyroid nodules (thyroid cancer)?

Answer 7

1) Papillary thyroid cancer (85%)
2) Follicular thyroid cancer (11%)
3) Anaplastic - undifferentiated cancer, v poor prognosis
4) Medullary cell thyroid cancer - genetic inherited cancer, autosomal dominant, can also get sporadic cancer
5) Thyroid lymphoma
6) Metastases from cancer elsewhere

Question 8

Describe the features of thyroid cancer

Answer 8

• Most common endocrine cancer
• 1% of all endocrine malignancies
• More common in women than men
• Most of the time is curable - Very good survival rate, most of the time the cancer is well differentiated, v good treatment options
• Overall DTC (differentiated thyroid cancer) 10 year survival 80-90%
• Low risk DTC (majority) - cancer specific mortality is < 1-2%

Question 9

How are most thyroid cancers detected?

Answer 9

1) Clinical detection
2) Imaging - mostly incidental
3) On pathology

Question 10

What factors increase your risk of thyroid cancer?

Answer 10

1) Radiation exposure incl. occupation hazard
2) FH esp. medullary thyroid cancer
3) MEN2 - hereditary condition where you can get multiple endocrine neoplasia (MEN) incl. medullary thyroid cancer
4) Hashimoto’s disease esp. increased risk of lymphoma
5) Cowden’s syndrome - genetic condition where get lots of cancer everywhere incl. skin, bowel, thyroid, renal

Question 11

What are the clinical/presenting features of thyroid cancer?

Answer 11

1) Rapidly enlarging painless mass in neck over past few weeks/months
2) Sudden pain in a thyroid lump
3) Unexplained hoarse voice - due to infiltration into recurrent laryngeal nerves
4) Neck lymphadenopathy - papillary cancer spreads via lymph nodes
5) Stridor - high pitched wheezing sound cause by disrupted airflow/fixation

Question 12

What does a painful lump in the neck typically indicate?

Answer 12

Bleed into a cyst

Question 13

What does stridor in thyroid cancer indicate?

Answer 13

• If the cancer has infiltrated into the trachea
• Usually in anaplastic cancer (locally invasive)
• Not usually seen in papillary or follicular cancer

Question 14

What investigations would you do to diagnose thyroid cancer?

Answer 14

1) TFTs
2) Calcitonin (tumour marker) - elevated
3) US
4) Fine needle aspiration (FNA) - if think the nodule is not benign, take sample

Question 15

When would calcitonin be elevated?

Answer 15

Medullary cancer

Question 16

Where is calcitonin produced?

Answer 16

Parafollicular C cells interspersed throughout the thyroid parenchyma

Question 17

How is an US used to diagnose thyroid cancer?

Answer 17

• Can only see positive signs
• Gold standard
• Can tell if nodule is benign or malignant

Question 18

How do you manage a benign thyroid nodule?

Answer 18

1) Monitor
2) If 2 follow up ultrasounds and no change in size then discharge
3) Surgery

Question 19

How do you treat a malignant thyroid nodule (thyroid cancer)?

Answer 19

1) Lobectomy followed by total thyroidectomy
2) Lymph node clearance.- depends on their involvement
3) Radioiodine if lymph node disease - much higher dose than for Graves’ - 2000/3000 becquerels vs 400
4) Lifelong monitoring - but classified into high risk and low risk

Question 20

Where are prominent thyroid lumps most likely to be?

Answer 20

Isthmus (middle)

Question 21

In what type of cancer might you see a hypoechoic or isoechoic solid lump (lesion) on US and what would you need to do in this case to diagnose?

Answer 21

• Follicular cancer

- Might need to do FNA

Question 22

What features on US indicate thyroid cancer?

Answer 22

1) If hypo-echoic (black) nodule could be tumour
2) If solid, > 4 cm high chance it is cancer
3) Irregular margin, no halo, infiltrative
4) Might see white bits in black nodule = micro calcification within nodule (positive sign of cancer)
5) Lump is more tall than wide (AP diameter is more than breadth)
6) Increased intranodular blood flow

Question 23

What should you do if the US scan is suspicious?

Answer 23

1) Do FNA

2) Refer to surgeon straightaway