PATH 5 Pathology of the Thyroid

Question 1

Cells of the Thyrooid?

Answer 1

Follicular Cells: T3/T4

C-Cells : Secretes Calcitonin

Question 2

CAUSES OF HYPERTHYROIDISM?

Answer 2

Diffuse toxic hyperplasia (Graves disease)

Toxic multinodular Goiter

Toxic adenoma (TSH Secreting)

Question 3

Classical Sign of Hyperthyroidism?

Answer 3

EXOPHTHALMOS

Question 4

CAUSES OF HYPOTHYROIDISM?

Answer 4

Insufficient thyroid parenchyma

• Congenital
• Radiation injury/Surgical ablation
• Hashimoto’s thyroiditis

Interference with hormone synthesis

• Heritable biosynthetic defect
• Iodine deficient
• Drugs (lithium)

Supra-thyroidal

• Pituitary lesion reducing TSH secretion
• Hypothalamic lesions reducing TRH

Question 5

Classical Sign of Hypothyroidism?

Answer 5

MYXODEMA

Question 6

__________________: Enlargement of the thyroid gland due to hyperplasia and colloid storage in conditions associated with abnormal production of thyroid hormones.

Causes?

Answer 6

Goiter can be caused by:

• Iodine deficiency
• Dietary goitrogens (Brussel Sprouts/Cabbage)
• Inherited enzyme in hormone synthesis.

Question 7

Thyroiditis Classificaitons?

• Acute: ____________
• Sub- Acute: __________
• Chronic: _______

Answer 7

Acute (Rare): bacterial/fungal/viral

Sub-Acute: de Quervain’s Thyroiditis

Chronic: Hashimoto’s Thyroiditis + Graves’ Disease

Question 8

_________________: most common chronic thyroiditis and thyroiditis causing HYPOTHYROIDISM

Cause?

Male/Female Impact?

Microscopy?

Answer 8

HASHIMOTO’S THYROIDITIS: Most common chronic thyroiditis and thyroiditis causing hypothyroidism.

• Autoimmune/blocking antibodies to TSH receptor on thyroid. When TSH produced by pituitary, no stimulation
• Female/Male ratio = 10:1

Microscopy:

Diffusely enlarged thyroid (4 –5 times normal).

Smooth or finely nodular surface.

Firm to hard consistency

Question 9

Common cause of HYPERTHYROIDISM caused by auto-immune IgG antibody vs TSH receptor (TSI)?

Answer 9

GRAVES’ DISEASE

Pathology: Diffuse enlargement, symmetrical, Hyperplastic follicles with papillary infoldings. (Scalloping)

Question 10

Most common type of Thyroid Carcinoma?

Answer 10

PAPILLARY CARCINOMA (Ecellent Prognosis)

Question 11

Prognosis/Genetic Causes of Papillary Carcinoma?

Old versus Young?

Answer 11

Excellent prognosis

BRAF (30-50%): OLDER, ADVANCED, EXTRATHYROIDAL

RET/PTC: YOUNGER, PSAMMOMA BODIES, EARLY STAGE, RADIATION

Genetics of RET/PTC Papillary Carcinoma

• RET protoncogene on Chromosome 10
• Encodes tyrosine kinase receptor not normally expressed
• Rearrangementsof Chrom. 10 put RET under control of promoter to give fusion gene called RET/PTC also T10/17
• Abnormal Gene product results in unregulated growth leading to papillary carcinoma of thyroid

Question 12

Condition associated with Ground glass, Orphan Annie appearance on histology?

Answer 12

PAPILLARY CARCINOMA

Question 13

Genetic Causes of Follicular Carcinoma?

Answer 13

Two types: Minimally Invasive, Widely Invasive

Genetics

• T(2;3)
• PAX8 fused with PPAR gamma1
• RAS Family Mutations (50%)

Question 14

Genetic Causes of Medullary Carcinoma?

Answer 14

80% sporadic

20% MEN2 A or B

BOTH associated with RET protooncogene germline mutations

Question 15

Prognosis/Genetic Causes of Anaplastic Carcinoma?

Answer 15

Typically older patient, thyroid swollen quickly

Mortality of 100% at one year.

BRAF Mutation

Question 16

Type of lymphoma that typically affects the thyroid?

Answer 16

Non-Hodgkin’s lymphoma