L2 Pathology of Thyroid Flashcards Preview

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Flashcards in L2 Pathology of Thyroid Deck (33):
1

What are some effects of thyroid hormones ?

1. Stimulate the contraction of heart
2. Increase oxygen consumption and heat production in all tissue
3. Stimulate gut motility
4. Important of CNS development
5. Stimulate production of structural proteins

2

What are the disorders of thyroid ?

1. Hyper
2. Hypo
3. Diffuse/nodular/multi-nodular goiter
4. Thyroid cancer (adenoma/ carcinoma )
5. Thyroiditis
6. Congenital > thyroglossal duct cyst

3

What is thyroglossal duct cyst ?

It is a fluid-filled cyst occurs anywhere along the thyroglossal duct in the midline
Most commonly near hyoid bone or attached to soft tissue

4

What is the structure of the cyst ?

1. Made of squamous or respiratory type epithelium
2. Variable amount of thyroid tissue

5

What type of tumor can develop in these cyst ?

Papillary carcinoma

6

What are the main causes of hyper?

1. Abnormal stimulator of the thyroid ( grave disease )
2. Intrinsic disease of thyroid ( toxic multi-nodular goiter / functional thyroid adenoma )
3. Abnormal secretion of TSH ( pituitary adenoma)

7

What are the triad for people with grave disease ?

1. Hyperthyroidism
2. Exophthalmus
3. Peri-tibial myxedema / clubbing

8

What are the gross and microscopic features of thyroid in grave disease ?

GROSS :
- moderately enlarged
- firm and beefy red ( due to increased vascularity )

MICROSCOPIC :
- lymphoid infiltrate
- glands show hyperplasia of :
* acinar epithelium
* tall columnar cells
* papillary folds

9

What is the cause of exophthalmus and peri-tibial myxedema ?

1. Lymphocytic infiltrate
2. Glycosaminoglycans ( hyaluronic acid ) deposition

10

What are the causes of hypothyroidism (myxedema ) ?

1. Iodine deficiency
2. Hashimoto disease
3. Drugs
4. Radiation / surgery

11

What are the types of thyroiditis ?

1. Acute thyroiditis ( bacterial or fungal infection )
2. Chronic autoimmune thyroiditis ( Hashimoto disease )
3. Granulomatous thyroiditis ( viral infection ):
- de queen
- giant cell thyroiditis
4. Subacute lymphocytic thyroiditis ( post-partum )
5. Riedel thyroiditis ( IgG-4 related - thyroid fibrosis )

12

What is the underlying cause of Hashimoto disease ?

It is an autoimmune disease caused by ab against :
1. ER
2. Thyroglobulin
3. Thyroperoxidase

Due to HLA B8 / DR5

13

What are the gross and microscopic features of Hashimoto disease?

Gross :
- firm diffuse goiter

Microscopic:
- follicle atrophy with lymphocyte
- hurthle cells ( eosinophilic epithelial cells )

14

What is the pathological mechanisms in Hashimoto disease ?

1. CD8+ cytotoxic T cell mediated killing
2. Cytokine mediated cell death ( interferon will activate more cells / Macrophages )
3. Binding of antithyroid antibodies then ADCC

15

What is the genetic cause of granulomatous thyroiditis?

HLA B35

16

What is the microscopic features of granulomatous thyroiditis ?

1. Patchy Micro abscess
2. Granulomas with giant cells

17

What is happening in the iodine deficiency goiter ?

Hyperplasia of the epithelium of the gland and appearance of less active areas that will be compressed by the hyper-plastic areas

18

What will lead to multi-modular goiter in iodine deficiency goiter ?

The tracts of fibrosis that will separate areas

19

What are the features of thyroid neoplasms ?

1. Most are solitary and benign
2. Low mortality rate
3. May be functional ( hot )

20

What are the main types of thyroid cancer ?

1. Papillary carcinoma ( most common )
2. Follicular adenoma
3. Follicular carcinoma
4. Anaplastic carcinoma
5. Medullary carcinoma ( least )

21

What is the gross and microscopic features of follicular adenoma ?

GROSS:
- solid mass with fibrous capsule that is not breached
- centre may contain areas of hemorrhage and cystic changes

MICROSCOPIC :
- compacted follicles
- lined with epithelial cells that show hyperchromtism
- little collied
- rarely, it can produce T3 and T4 so considered as hot

22

Which age is usually affected by each type of thyroid cancer ? What is the prognosis ?

1. Papillary carcinoma ( young adults >45 ) ( only 5% is familial )
2. Follicular ( young middle < 45 )
3. Anaplastic ( elderly / very poor prognosis )
4. Medullary ( elderly / can be familial which will be more aggressive )

23

What are the possible risk factors of papillary carcinoma ?

1. High iodine intake
2. Radiation
3. Genetic factors
4. Somatic mutations

24

What are the different somatic mutations that increase the risk of papillary carcinoma?

1. Familial granulomatous polyposis
2. Somatic rearrangement of RET proto-oncogenes on chromosome 10
3. Chromosomal rearrangement of RET or NTRK1
4. Mutations in BRAF

25

What is the gross and microscopic features of papillary carcinoma ?

GROSS :
1. Non-encapsulated infiltrative mass
2. Firm and whitish due to fibrosis

MICROSCOPIC:
1. Epithelial papillary projections
2. Psammoma bodies
3. Characteristic nuclei with central clear mass ( orphan Annie nuclei )

26

Through what does the papillary and follicular carcinoma metastasize ?

1. Papillary > lymphatics to cervical lymph node
1. Follicular > blood vessels to bones and lungs

27

Why follicular carcinoma has god prognosis ?

As many tumors retain their ability to uptake the I311 ( radiotherapy )

28

What are the possible genetic causes underlying follicular carcinoma?

Either
- RAS mutations
Or
- PAX8-PPAR gamma 1 rearrangement

29

What are anaplastic carcinoma ? and what is the microscopic features ?

- It is poorly differentiated adenocarcinoma from thyroid epithelium
- It has many histological appearances but the commonest is :
* giant cell
* spindle cell

30

Why anaplastic carcinoma has very poor prognosis ?

Due to rapid local invasion

31

What is medullary carcinoma ?

Derived from C cells

32

What does medullary carcinoma secrete ?

1. Calcitonin
2. Serotonin
3. ACTH
4. somatostatin

33

What are the features of the tumor in medullary carcinoma?

1. Solid mass
2. Sheets of neoplastic cells
3. Hyaline stroma
4. Amyloid reactions