Endocrine Neoplasia

Question 1

What is the key histology of the thyroid gland?

Answer 1

Thyroid follicular cells form circular edges around colloid = thyroid follicle
Colloid contains thyroglobulin which is secreted from follicular cells -> formation of T3 andT4
Parafollicular cells or C cells ->secrete calcitonin
Stroma

Question 2

What is meant by a thyroid nodule?
How does it present?

Answer 2

A solitary thyroid nodule - unusual growth on thyroid (fluid or solid)
Palpable/visible swelling of the thyroid gland
Up to 10% incidence
Pressure symptoms
Pain

Question 3

What is thyroid neoplasia?
How does it normally present?

Answer 3

Abnormal growth in the thyroid gland
Thyroid nodules are common
Benign : Malignant 10:1
Increased frequency with age
Solitary nodule > neoplastic
Solitary nodule in young person more likely to be cancerous than in older person
More common in female

Question 4

What test should be done to identify thyroid malignancy?

Answer 4

Serum TSH
(as growth factor stimulate growth of thyroid tissue including cancer cells)

Question 5

What factors are important to understand in a history surrounding the thyroid lump?

Answer 5

Duration of swelling
Risk factors - radiation to head/neck
Family history - MEN syndrome
Concerning features - rapid growth, pressure symptoms, hoarseness of voice (vocal cord paralysis)
Lump - fixed and hard, lymphadenopathy, signs of hyper/hypothyroidism

Question 6

What is thyroid scintigraphy?
How to interpret it?

Answer 6

Type of nuclear imaging, uses a radiotracer that mimics Iodine
Taken up by thyroid gland - shows activity of te thyroid gland in terms of T3/4 production
Hot nodules - more intense signal - increased uptake
Cold nodules - less intense signal - reduced uptake.

Question 7

What type of thyroid nodule is more common hot or cold?

Answer 7

Cold nodules are more common (85%) compared to hot/functional nodules (15%)

Question 8

How does hot(functional) or cold thyroid nodule relate to cancer risk?

Answer 8

Cold - 15% malignant
Hot - 5% malignant

Note patients are more likely to have a cold nodule, cold nodules are more likely to be malignant that hot.

Question 9

What is the gold standard test for evaluation of a thyroid nodule?

Answer 9

Fine needle aspiration cytology (FNAC)
Safe, accurate and cost effective

Question 10

When/how is a fine needle aspiration done for a thyroid nodule?

Answer 10

For nodules >1cm
Is palpation or ultraound guided
Uses a 23-27 gauge needle

Question 11

What are the signs on cytology of thyroid cancer?

Answer 11

Look at thyroid follicular cells
Bubble in nucleus = intranuclear inclusion
Line through nucleus = nuclear groove

Question 12

What are the different rating for thyroid cytology results?

Answer 12

Thy1 to Thy5
Thy1 - non diagnostic (not enough cells) cancer risk 5 to 10%
Thy2 - benign, up to 3% risk
Thy3a - insignificant atypia (up to 30% risk)
Thy3f - follicular neoplasm - up to 40% risk
Thy4 - suspicious for malignancy - up to 75% risk
Thy5 - malignant up to 99% risk

Question 13

Give an example of a benign thyroid neoplasia

Answer 13

Thyroid adenoma / follicular adenoma

Question 14

Give some examples of malignant thyroid neoplasia

Answer 14

Follicular thyroid carcinoma
Papillary thyroid carcinoma
Medullary carcinoma
Anaplastic carcinoma

Question 15

What is the most common malignant thyroid tumour?

Answer 15

Papillary thyroid carcinoma = 85%

Question 16

How does the lump in papillary thyroid carcinoma present?

Answer 16

Solitary or multifocal
Well-circumscribed or encapsulated or infiltrative
Cauliflower like gross appearance

Question 17

What is the histological appearance of a papillary thyroid carcinoma?

Answer 17

Branching Papillae - finger like projections lined by cancerous cells
Cancerous cells appear empty
On closer inspect have a circular ring to the nucleus (intranuclear inclusions)

Question 18

What is the clinical course of papillary thyroid carcinoma?

Answer 18

Tends to metastasise through the lymphatic channels -> cervical lymph nodes
Excellent prognosis with a 95% 10 year survival

Question 19

What are the treatment options commonly used for papillary thyroid carcinoma?

Answer 19

Surgery for >1cm
If less than 1cm - papillary microcarcinoma may use active surveillance.

Question 20

How does a thyroid adenoma/follicular adenoma lump present?

Answer 20

Benign
Solitary and painless
Encapsulated - does NOT invade surrounding capsule/vasculature
Large = pressure symptoms and difficulty swallowing

Question 21

How does thyroid adenoma/follicular adenoma appear on diagnostics?

Answer 21

On radioiodine scan - is a cold nodule
Fine needle aspiration - Thy3f

Question 22

What is the typical treatment for a thyroid adenoma/follicular adenoma?

Answer 22

Surgical excision with capsule intact

Question 23

How common are follicular carcinoma of the thyroid?

Answer 23

5-15% of thyroid carcinoma

Question 24

How does follicular carcinoma present on exam and investigation?

Answer 24

Solitary nodule, slowly enlarging
Frequently cold on scintigraphy, but may appear warm - requires FNA

Question 25

How to differentiate between follicular adenoma v follicular carcinoma on cytology/histology?

Answer 25

On histology both show colloid containing follicles uniform nuclei, encapsulated In histology adenoma does not show capsular and vascular invasion Carcinoma - shows capsular and vascular invasion (mushroom-shaped) Must have histology and FNAC will not show a difference

Question 26

Is this a follicular adenoma or carcinoma? How can you tell?

Answer 26

Adenoma Intact capsule surrounding the tumour - no capsular or vascular invasion

Question 27

In reference to the histology below, how do you differentiate between a follicular adenoma/carcinoma?

Answer 27

Adenoma = A = respects thin capsule boundaries Carcinoma = B = mushroom shaped invasion of tumour (more purple) into surrounding capsule and tissue (Light pink)

Question 28

What is the clinical coures of follicular thyroid carcinoma?

Answer 28

Tends to metastasise through the blood vessels to the bone, lungs and liver. (commonly lumps on scalp) Prognosis depends on extent of invasion and stage at presentation Widely invasive <10yrs Minamally invasive - >90% survival at ten years

Question 29

What is the most common treatment for follicular thyroid carcinoma?

Answer 29

Total thyroidectomy Radioactive iodine for Mets

Question 30

What is meant by anaplastic carcinoma of the thyroid?

Answer 30

"Lack of differentiations" to form backwards Agressive tumour - mean age of honest is 65yrs. Invasion of neck structures - dyspnea, dysphagia, hoarness and cough Metastatsis Mortality rate near 100%

Question 31

What carcinoma of the thyroid is this?

Answer 31

Anaplastic carcinoma of the thyroid High pleomorphic, multinucleated cells High grade tumour

Question 32

What is medullary carcinoma of the thyroid?

Answer 32

Originates from parafollicular cells or C cells Neuroendocrine tumour Increase calcitoninc levels 70% are sporadic rest are associated with MEN2A/2B

Question 33

What thyroid carcinoma is this?

Answer 33

Salt and pepper chromatin Forms sheets and layers Calcitonin deposits (pink material ) in the stroma are termed amyloid. Medullary thyroid carcinoma

Question 34

What is multiple endocrine neoplasia?

Answer 34

MEN syndrome Autosomal dominant - genetic disorder Causes proliferative/neoplastic disorders in multiple endocrine organs Starting asymptomatic hyperplasia of organs Tumours occur at younger age Can affect multiple organs - simultaneous or different times

Question 35

What are the two different types of MEN syndrome?

Answer 35

MEN 1 MEN 2A/2B

Question 36

What are the genetics of MEN 1 syndrome?

Answer 36

Affects the menin gene on chromosome 11 Inactivating mutation

Question 37

What is the genetics of the MEN2A/2B syndrome?

Answer 37

Affects the RET protoncogene Chromosome 10 Gain of function mutation.

Question 38

What endocrine organs are commonly affected in MEN 1?

Answer 38

Pituitary Parathyroid Pancreatic endocrine

Question 39

What are the endocrine organs commonly affect in MEN2A syndrome?

Answer 39

Medullary thyroid Parathyroid Bilateral phaeochromocytoma

Question 40

What are the endocrine organs commonly affected in MEN 2B syndrome?

Answer 40

Neuromas (nerves in mouth, lips, tongue) Medullary carcinoma of the thyroid Phaeochromocytoma