Thyroid cancer

Question 1

Very simply, describe the basis of thyroid carcinoma.

Answer 1

Overtime, uncontrolled cell division in the thyroid will lead to formation of a nodule. These nodules tend to be ‘cold’, non-functional nodules and do not produce thyroid hormones.

Question 2

Name the 5 types of thyroid carcinoma,

Answer 2

Papillary
Follicular
Hürthle cell
Medullary 
Anaplastic

Question 3

1) Describe what is meant by differentiated thyroid carcinoma.
2) Which types of thyroid carcinoma are differentiated?

Answer 3

1) Carcinomas arising from follicular cells which look and act like normal thyroid cells.
2) Papillary, follicular and Hürthle cell neoplasms.

Question 4

1) What is the most common thyroid cancer?

2) What is the second most common thyroid cancer?

Answer 4

1) Papillary

2) Follicular

Question 5

1) Where do papillary thyroid cancers spread to?
2) What mutations are papillary thyroid cancers associated with?
3) What environmental factor is papillary thyroid cancer associated with?

Answer 5

1) Cervical lymph nodes
2) Associated with RET and BRAF gene mutations.
3) Exposure to ionising radiation in childhood.

Question 6

What is the basis behind the name ‘papillary thyroid carcinoma’?

Answer 6

Due to finger-like projections which tend to grow slowly near to lymphatic vessels and invade lymph nodes in the neck.

Question 7

Describe the cells visible in papillary thyroid cancer.

Answer 7

Cells contain an empty looking nucleus with few proteins and a small amount of DNA.
There will also be the presence of psammoma bodies which are calcium deposits within the papillae.

Question 8

1) Where does follicular thyroid cancer spread to?
2) What is follicular thyroid cancer associated with environmentally?
3) What occurrences within genes can follicular thyroid cancer be associated with?
4) What structures do follicular thyroid cancers not typically invade?

Answer 8

1) Bone and lungs.
2) Associated with low dietary iodine.
3) Activation of RAS oncogene or deactivation of PTEN tumour suppressor gene.
4) Do not typically invade nearby lymph nodes.

Question 9

Describe the basic pathophysiology of follicular thyroid cancer.

Answer 9

Tumour develops from follicular cells and grows until it breaks through the fibrous capsule.
Follicular carcinomas can then invade nearby blood vessels and spread to the lungs, liver, bone and brain.

Question 10

1) What is Hürthle cell thyroid carcinoma?
2) How are Hürthle cells formed?
3) Where are Hürthle cells also seen?

Answer 10

1) A rare variant of follicular cell carcinoma.
2) Follicular cells adapt to inflammation and stress by becoming Hürthle cells. They do this by increasing the production of mitochondria, giving cells a granular appearance. These cells can then form neoplastic tumours which can break through the fibrous capsule and invade the bloodstream.
3) In Hashimoto’s thyroiditis.

Question 11

1) Where do medullary thyroid carcinomas arise from?
2) Where do medullary thyroid tumours normally arise and why?
3) What is usually the cause of the formation of medullary thyroid carcinomas?

Answer 11

1) Parafollicular cells.
2) In the upper third of the thyroid medulla as there are higher concentrations of parafollicular cells present there. Normally develop unilaterally.
3) A sponteneous mutation in the RET oncogene.

Question 12

1) What does familial medullary thyroid carcinoma cause?

2) What do type 2a and 2b multiple endocrine neoplasia cause?

Answer 12

1) Multiple thyroid carcinomas.

2) Multiple tumours across different endocrine glands (thyroid, parathyroid and adrenals).

Question 13

1) What are multiple endocrine neoplasia tumours made up of?

2) Where do medullary thyroid carcinomas often spread to?

Answer 13

1) Spindle shaped cells.

2) Lymph nodes.

Question 14

1) What can anaplasitc thyroid carcinomas develop from?
2) Whom is more likely to be affected by Anaplastic thyroid carcinomas?
3) Where do anaplastic thyroid carcinomas often spread to?
4) What types of cells do anaplastic thyroid carcinomas contain?

Answer 14

1) Existing papillary/ follicular cancers, and then can mutate further, creating unrecognisable cells.
2) Tends to affect older patients and is more aggressive than other types, giving a poor prognosis.
3) Lymph nodes. They can grow beyond the fibrous capsule and cause local invasion as well by invading nearby structures.
4) Spindle shaped cells and pleomorphic giant cells (enlarged cells that vary in shape).

Question 15

1) What does thyroid carcinoma most commonly present as?
2) Describe the presentation of a thyroid carcinoma in terms of the nodule.
3) Upon palpation, which types of nodules are more likely to be thyroid tumours?

Answer 15

1) An asymptomatic thyroid nodule detected by palpation of USS in a woman in her 30s/ 40s.
2) Often a solitary, painless nodule.
3) Hard, immovable nodules are more likely to be tumours.

Question 16

Aside from a nodule, give 6 other potential characteristics of thyroid carcinoma on clinical presentation.

Answer 16

Hoarseness/ trouble swallowing: if tumour invades larynx or oeseophagus.
Diarrhoea: usually in medullary thyroid cancer.
Flushing of skin: usually in medullary thyroid cancer due to increased serotonin levels.
Dyspnoea: if there is tracheal pressure
Tracheal deviation
Cervical lymphadenopathy.

Question 17

Which blood tests should be carried out if a thyroid carcinoma is suspected?

Answer 17

TFTs: TSH, T3 and T4 should be normal in thyroid carcinoma.
Calcitonin: elevated in medullary thyroid carcinoma.

Question 18

1) What is often the first line investigation for suspected thyroid carcinoma?
2) How should malignant lesions appear on an isotope scan?
3) What is a hyper functioning/ hot lesions more likely to represent?

Answer 18

1) USS to identify the nodule.
2) Should appear cold.
3) An adenoma (benign)

Question 19

1) What is the most important diagnostic test for thyroid carcinoma?
2) Why might a laryngoscopy be required in patients with suspected thyroid carcinoma?

Answer 19

1) Fine needle aspiration cytology which use used to identify the type of tumour.
2) To investigate vocal cords. Paralysed vocal cords may be suggestive of malignancy.

Question 20

1) What does management of thyroid cancer depend on?
2) How is anaplastic thyroid carcinoma often managed?
3) Before any thyroid surgery for thyroid cancer, what needs to be done?

Answer 20

1) Histological classification.
2) De-bulking surely, palliative radiotherapy and palliative care.
3) The patient needs to be rendered euthyroid by using medication.

Question 21

1) How should differentiated thyroid cancers be treated?
2) How should medullary thyroid cancer be treated?
3) What should be given after thyroid surgery and radio ablation for thyroid cancer?

Answer 21

1) Partial/ total thyroidectomy ± node excision + post-operative radioactive ablation (if tumour was >1cm)
2) Total thyroidectomy + node clearance. External beam radiotherapy may prevent regional recurrence.
3) Levothyroxine to suppress TSH (lifelong).