Pathology of the thyroid gland

Question 1

What does the thyroid gland develop from embryologically?

Answer 1

an evagination of pharnygeal epithelium

Question 2

What causes inlgual thyroid?

Answer 2

failure of descne of thyroid from tongue

Question 3

How do you tell a thyroglossal duct cyst?

Answer 3

will move on swallowing; in the midline of the neck

Question 4

What type of cells surrounds each follicle?

Answer 4

flat to cuboidla follicaular epithelial cells

Question 5

What does TSH bind to in the thyroid?

Answer 5

TSH receptor on surface of thyroid epithelial cells

Question 6

How does binding to the TSH receptor induce release of T3 and T4?

Answer 6

G proteins stimulate production of cAMP which increases production and release of T3 and T4

Question 7

What do T3 and T4 bind to the nucleus?

Answer 7

thyroid response elements

Question 8

Aside from Grave’s, what else can cause hyperthyroidism?

Answer 8

hyperfunctioning nodules/ tumours, thyroiditis; TSH secreting pituitary adenoma; ectopic production (struma ovarii); factitious (exogenous intake)

Question 9

What are the 2 autoimmune diseases affecting the thyroid gland?

Answer 9

Hashimoto’s thyroiditis and Grave’s disease

Question 10

What are antibodies produced against in Grave’s disease?

Answer 10

TSH receptor; thyroid peroxisomes; thyroglobulin

Question 11

What are the types of anti-TSH receptor antibody in Grave’s disease?

Answer 11

thyroid stimulaating immunoglobulin; thyroid growth stimulating immunoglobulin; TSH biding inhibitor immunoglobulin

Question 12

What is the most specific Ab for Grave’s?

Answer 12

thyroid stimulating immunoglobulin

Question 13

What might the presesnce of TSH binding inhibitor immunoglobulin hlpe explain?

Answer 13

episodes of hypofunction

Question 14

What are the triad of features seen with Grave’s disease?

Answer 14

hyperthyroidisim with diffuse enlargement of the thyroid; eye changes; pretibial myxoedema

Question 15

What do the eye changes in Grave’s result from?

Answer 15

fibroblasts etc. expressing TSH receptors

Question 16

What are the antibodies found in Hashimoto’s thyroiditis?

Answer 16

anti-thyroglobulin and anti-peroxidase

Question 17

What is the difference in antibodies in Hashimoto’s and Grave’s and why does this cause differences in clinical picture?

Answer 17

the main antibody in Grave’s is anti-TSH receptor antibody, which stimulates the receptor to produce more T3 and T4 but is not affected by the feedbakc loop. In Hashimoto’s, the main antibodies are made against thyroglobulin- a precursor of T3 and T4 and peroxidase- an ezyme used to make T3 and T4

Question 18

What is Hashitoxicosis?

Answer 18

transient hyperfunction before decrease in function in Hashimoto’s

Question 19

What are pts with Hashimoto’s more at risk of developing in the thyroid?

Answer 19

B cell NHL (lymphoma)

Question 20

What causes diffuse goitre?

Answer 20

reduced T3/T4 production causes rise in TSH stimulating gland enlargement to maintain euthyroid state

Question 21

What can cause diffuse goitre?

Answer 21

ingestion of substances limiting T3/T4 production; inborn errors of metabolism (dyshormonogenesis)

Question 22

What is seen on blood tests in patients with diffuse goitre?

Answer 22

T3/T4 normal but TSH high or upper limit of normal

Question 23

What do patients usually present with with diffuse goitre?

Answer 23

mass effects (usually euthyroid)

Question 24

What can dyshormonogenesis lead to in children?

Answer 24

cretinism

Question 25

What does multi-nodular goitre develop from?

Answer 25

long-standing simple goitre- recurrent hyperplasia and involution

Question 26

What should you suspect in patients with multi-nodular goitre?

Answer 26

thyroid neoplasm

Question 27

Why can people with multi-nodular goitre develop hyperthyroidism?

Answer 27

may develop an autonomous nodule

Question 28

What is the type of adenoma seen with thyroids?

Answer 28

follicular adenoma

Question 29

What types of carcinoma are seen in the thyroid?

Answer 29

papillary; follicular; medullary; anaplastic

Question 30

What are the features of a follicular adenoma?

Answer 30

discrete solitary mass; encapsulated by a surroudning collagen cuff; compaosed of neoplastic thyroid follicles

Question 31

What can an adenoma be difficult to distinguish from?

Answer 31

dominant nodule in multinodular goitre; follicular carcinoma

Question 32

Are thyroid carcinomas more common in females or males?

Answer 32

females

Question 33

What age group gets thyroid carcinoma?

Answer 33

early adulthood

Question 34

What type of carcinoma is associated with ionising radiation?

Answer 34

papillary carcinoma

Question 35

What type of carcinoma is associated with iodine deficiency?

Answer 35

follicular carcinoma

Question 36

What is the most common form of thyroid cancer?

Answer 36

papillary carcinoma

Question 37

How does papillary carcinoma usually present?

Answer 37

solitary nodule- can be mulitofcal; often cystic; may be calcified- Psammoma bodies on biopsy

Question 38

What is the difference between the spread of papillary and follicular carcinoma?

Answer 38

papillary goes through lymph whereas follicular tends to spread haematogenously

Question 39

How do you distinguish between follicular carcinoma and adenoma?

Answer 39

carcinoma will have vascular or capsular invasion

Question 40

What cells are medullary thyroid carcinomas derived from?

Answer 40

c-cells

Question 41

What does amyloid represent?

Answer 41

deposition of an abnormally folded protein

Question 42

What is anaplastic carcinoma?

Answer 42

undifferentiated and aggressive tumours- may arise in patients with a Hx of differentiated thyroid chancer whic hhas then dedifferentiated

Question 43

How many parathyroid glands do most people have?

Answer 43

4

Question 44

What type of cells are parathyroid glands composed of?

Answer 44

chief cells

Question 45

How do chief cells appear?

Answer 45

roudn cells with moderate cytoplasm and bland roudn central nuclei

Question 46

What type of cell suppports the chief cells in the parathyroid?

Answer 46

oxyphil cells

Question 47

What type of cytoplams do oxyphil cells have?

Answer 47

acidophilic

Question 48

What does PTH do?

Answer 48

acts on calcium homeostasis

Question 49

What does hyperparathyroidism normally result from?

Answer 49

small adenomas

Question 50

What else can causes hyperparathyroidism?

Answer 50

hyperplasia; carcinoma

Question 51

What is the difference between an adenoma nad hyperplasia in the parathyroid glands?

Answer 51

adenoma is a single gland involved but hyperplasia typically involves all the glands

Question 52

What causes secondary hyperparathyroidism?

Answer 52

chronic hypocalcaemia

Question 53

What is tertiary hyperparathyroidism?

Answer 53

when parathyroid activity becomes autonomous - hypercalcaemia

Question 54

What are the consequences of hyperparathyroidism?

Answer 54

bone disease; nephrolithiasis; GI complications- constipation; nausea; peptic ulcer disease; pancreatitis; glla stones; CNS- depression; lethargy; seizures; calcification of aortic and mitral valves; wekaness anf fatigue

Question 55

What congenital problem can cause hypoparathyroidism?

Answer 55

diGeorge syndrom

Question 56

What is seen with hypoparathyroidism?

Answer 56

tetany; altered mental state; parkinsonism; calcification of lens and cataract formation; prolonged QT interval in ECG