Thyroid Nodules and Cancer Flashcards
What is a toxic thyroid nodule?
An autonomous nodule on the thyroid which doesn’t obey the feedback, just autonomously keeps making excess thyroid hormone
What are the three ways to diagnose thyroid nodules?
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
What size are palpable nodules?
> 1 cm (if < 1cm, easy to miss)
What % of thyroid nodules are benign?
95% (may be lower)
What are risk factors for thyroid nodules?
1) Women
2) Age
What should be done if a thyroid lump is detected?
Pt should be referred to clinical to do further imaging to determine if it is benign or malignant (US)
What are causes of malignant thyroid nodules (thyroid cancer)?
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
Describe the features of thyroid cancer
- 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%
How are most thyroid cancers detected?
1) Clinical detection
2) Imaging - mostly incidental
3) On pathology
What factors increase your risk of thyroid cancer?
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
What are the clinical/presenting features of thyroid cancer?
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
What does a painful lump in the neck typically indicate?
Bleed into a cyst
What does stridor in thyroid cancer indicate?
- If the cancer has infiltrated into the trachea
- Usually in anaplastic cancer (locally invasive)
- Not usually seen in papillary or follicular cancer
What investigations would you do to diagnose thyroid cancer?
1) TFTs
2) Calcitonin (tumour marker) - elevated
3) US
4) Fine needle aspiration (FNA) - if think the nodule is not benign, take sample
When would calcitonin be elevated?
Medullary cancer
Where is calcitonin produced?
Parafollicular C cells interspersed throughout the thyroid parenchyma
How is an US used to diagnose thyroid cancer?
- Can only see positive signs
- Gold standard
- Can tell if nodule is benign or malignant
How do you manage a benign thyroid nodule?
1) Monitor
2) If 2 follow up ultrasounds and no change in size then discharge
3) Surgery
How do you treat a malignant thyroid nodule (thyroid cancer)?
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
Where are prominent thyroid lumps most likely to be?
Isthmus (middle)
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?
- Follicular cancer
- Might need to do FNA
What features on US indicate thyroid cancer?
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
What should you do if the US scan is suspicious?
1) Do FNA
2) Refer to surgeon straightaway
