Thyroid Pathology

Question 1

Why are fine needle aspirates used instead of biopsies for the thyroid?

Answer 1

Thyroid is highly vascular therefore biopsies are dangerous

Question 2

What effects does TSH have on the thyroid apart production of thyroid hormone?

Answer 2

Hyperplasia

Hypertrophy

Increase coroid production

Question 3

What type of cells surround thyroid follicles?

Answer 3

Epithelial

Question 4

How can you tell that a thyroid follicle is active?

Answer 4

Scalloping of the coroid

The columnar epithelial cells are taller

Question 5

Does Hashitoxicosis cause hypothyroidism or hyperthyroidism?

Answer 5

Hyperthyroidism

Question 6

Hypothyroidism causes what symptoms?

Answer 6

Hypometabolic state

– Cold intolerance; cold thickened skin; alopecia
– Weight gain (despite decreased appetite); fatigue

• Sympathetic nervous system underactivity

– Bradycardia, angina, CHF; slow-relaxing reflexes
– GI (constipation);mood, concentration; other…

• Children: developmental abnormalities, cretinism
• TSH,fT4(generally)

Question 7

What are the 4 most common causes of hypothyroidism?

Answer 7

Iodine deficiency

Hashimoto’s thyroiditis

Iatrogenic

Thyroid removal

Question 8

What are the symptoms of hyperthyroidism?

Answer 8

• Hypermetabolic state
– Heat intolerance; warm flushed skin; fatigue
– Weight loss (despite increased appetite); osteoporosis

• Sympathetic nervous system overactivity
– Palpitations, atrial fibrillation, cardiomegaly, CHF

– Tremor, anxiety, insomnia, emotional lability – GI (diarrhoea), MSK, ocular (lid lag), other…

Exophthalmos

Question 9

Is thyrotoxicosis the same as hyperthyroidism?

Answer 9

No, thyrotoxicosis is excess thyroid hormones by any means not necessarily a overactive thyroid

Question 10

T/F Simple goitres are usualy euthyroid

Answer 10

True

Question 11

How do simple goitres occur?

Answer 11

Thyroid hormone decrease (via some mechanism eg iodine deficiency) > TSH increases > Stimulates growth of the thyroid > Normal levels of thyroid hormone are achieved

Question 12

What are some causes of simple goitre?

Answer 12

Iodine deficiency

Goitrogen consumption

Question 13

How do simple goitres appear histologically?

Answer 13

Hyperplastic

Follicles lined by crowded cells

Some follicles are larger than others

May have large colloid-filled cysts

Question 14

How do simple goitres become multinodular?

Answer 14

Prolonged stimulation with TSH can cause follicles to rupture and fibrose or become large nodules

Question 15

What are Toxic multinodular goitres?

Answer 15

Goitres nodules that have been independent of TSH and hyperactive

Question 16

When don’t Toxic multinodular goitres cause hyperthyroidism?

Answer 16

When there isn’t enough iodine to produce the thyroid hormones

Question 17

What is Pemberton’s sign?

Answer 17

When there is venous congestion due to the goitre

Question 18

How do you treatment simple or nodular goitres?

Answer 18

Iodine or thyroid hormone

Surgery

Question 19

What are the four histology signs of Hashimoto’s disease?

Answer 19

• Formation of lymphoid follicles
• Marked changes in thyroid epithelial cells
• Extensive formation of new connective tissue
• Diffuse “round cell” infiltration

Question 20

What are Hürthle cells?

Answer 20

Thyroid cells with seen in Hashimoto’s with abundant, eosinophilic, granular cytoplasm

Question 21

How does the thyroid gland appear in Hashimoto’s disease?

Answer 21

Pale

Firm

Tan-yellow

Nodular

Question 22

What is the immune mechanism of Hashimoto’s thyroiditis?

Answer 22

• CD8+ cytotoxic cell-mediated cell death
• Cytokine-mediated cell death (e.g. IFN-γ, Fas)
• Maybe Antibody-dependent cell-mediated cytotoxicity
• TSH-blocking ABs further reduce thyroid function

Question 23

What is the histopathology of Grave’s disease?

Answer 23

• Follicular cells are tall and more crowded: diffuse hypertrophy and hyperplasia

– May form papillae in follicle lumen

• Widespread scalloping of colloid

– Colloid is often paler-staining

• Lymphocytic infiltrates

Question 24

What is the gross pathology of the thyroid in Grave’s?

Answer 24

Diffusely larger

Soft and meaty

Question 25

When does Grave’s disease cause hypothyroidism?

Answer 25

When there are thyroid inhibiting antibodies acting on TSH receptors

Question 26

What causes Grave’s disease Ophthalmopathy?

Answer 26

• Retro-orbital hydrophilic mucopolysaccharides, oedema, lymphocytes, fibrosis, and fat
• Fibroblasts Express TSH-like antigens

– Produce more hyaluronic acid (GAG: osmotic++)

– Transform into adipocytes

Question 27

What type of hypersensitivity is Hashimoto’s disease

Answer 27

IV