Thyroid.parathyroid pathology 1

Question 1

Describe the histology of the thyroid gland

Answer 1

• Comprises of follicles
• Each follicle surrounded by flat to cuboidal follicular epithelial cells
• Colloid contains thryoglobulin
• Scattered amoing the follicles is parafollicular (C-cells) cells

Question 2

What is thyroglobulin ?

Answer 2

The protein on which T3 and T4 are synthesised

Question 3

What do C-cells secrete ?

Answer 3

Calcitonin

Question 4

What are some of the common pathologies affecting the thyroid gland ?

Answer 4

• Hyperthyroidism/ Thyrotoxicosis
• Hypothyroidism
• Goitre
• Neoplasia

Question 5

What are the antibodies commonly seen in Graves disease causing hyperthryoidism ?

Answer 5

TSH receptor antibodies

Question 6

Define euthyroid

Answer 6

Normal function thyroid

Question 7

What is the most common thyroid disease ?

Answer 7

Non-toxic nulti-nodular goitre

Question 8

What is non-toxic mutli-nodular goitre ?

Answer 8

• Nodular enlargement of the thyroid gland
• Affected individuals can be either euthyroid or hypothyroid

Question 9

How does non-toxic multi-nodular goitre arise ?

Answer 9

1. Result from absolute or relative iodine deficiency
2. Results in increased TSH secretion
3. This induces hyperplasia in an attempt to increase thyroid hormone output
4. These increased demands are usually intermittent and the gland therefore undergoes cycles of growth and shrinkage
5. End result is nodules of varying size with fibrosis, haemorrhage and focal inflammation seen

Question 10

What are some of the complications of mutli-nodular goitres ?

Answer 10

• May produce symptoms suggestive of tumour
• Can cause compression of trachea, oesophagus, or recurrent laryngeal nerve

Question 11

What are some of the histological features seen in graves disease causing hyperthroidism ?

Answer 11

• Gland is hyperplastic and hyperaemic
• Thyroid epithelium is hyperplastic and there is little coloid storage

Question 12

What antibody is usually present in hashimotos disease causing hypothyroidism

Answer 12

High-titre antiperoxidase

Question 13

What are the typical histological features of hashimotos thyroiditis ?

Answer 13

Gland is widely infiltrated by lymphocytes, plasma cells, macrophages

Thyroid follicular cells are enlarged with eosinophilic granular cytoplasm due to accumulation of mitochondria

Question 14

Define what a goitre is

Answer 14

Any enlargement of the thyroid gland

Question 15

What are the main types of goitres and how does a goitre occur ?

Answer 15

Diffuse and mutli-nodular goitres

• Diffuse = entire goitre becomes enlarged
• Multi-nodular = lots of nodules of enlargement

Occur due to Reduced T3 / T4 production causing a rise in TSH, stimulating gland enlargement

Question 16

What are the usual thyroid function results for diffuse goitres ?

Answer 16

T3 / T4 normal but TSH high or upper limit of normal due to increased TSH compensating

Question 17

Where are the parathyroid glands located ?

Answer 17

You have 4 (2 upper and 2 lower) located posterior to the thyroid gland

Question 18

What are the 2 main cell types which the parathyroid glands are made up of

Answer 18

Chief cells and Oxyphil cells

Question 19

What is the function of chief cells in the parathyroid glands ?

Answer 19

• Secrete PTH
• Act on Ca homeostasis (regulates calcium levels)