Pathology of Thyroid Flashcards
What is the thyroid composed of, and what is each of these surrounded by?
Composed of follicles. Each follicle surrounded by flat to cuboidal follicular epithelial cells.
What is found within the centre of each follicle?
dense amorphic pink material containing thyroglobulin
What are C cells? What do they secrete?
(parafollicular cells). Slightly larger cells with clearer cytoplasm. Secrete calcitonin
What does TSH bind to?
TSH receptor on surface of thyroid epithelial cells.
What does cAMP do?
cAMP increases production and release of T3 and T4
Do T3 and 4 circulate in bound or free forms?
both
What occurs as a result of excess T3 and T4?
hyperthyroidism
What are 85% of hyperthyroidisms due to?
Grave’s Disease
Is hashimotos thyroiditis related to hypo or hyperfunction of the thyroid?
hypo
What type of condition are Hashimoto’s
Thyroiditis and Grave’s disease?
autoimmune
Descriebe the triad of features in Grave’s disease.
Hyperthyroidism with diffuse enlargement of the thyroid
Eye changes (exophthalmos)
Pretibial myxoedema.
Why do eye changes occur in Grave’s Disease?
The eye changes result from fibroblasts etc expressing TSH receptors
Who does Hashimotos commonly affect?
Affects middle aged women
Which genes is Hashimoto’s associated with?
Associated with HLA – DR3 and DR5
Can iodine deficiency cause hyper or hypothyroidism?
hypo
Is hypothyroidism often a result of secondary (pituitary) or tertiary (hypothalamic) pathology?
no, rarely
What may mediate destruction of thyroid epithelium?
CD8 +ve cells
What may hashimoto’s be preceded by?
by transient hyperfunction (Hashitoxicosis)
What causes a goitre?
Reduced T3 / T4 production causes rise in TSH, stimulating gland enlargement
If a goitre is present, can you maintain euthyroid state?
Yes (If compensation fails have goitrous hypothyroidism
)
What are the most common type of thyroid carcinomas?
papillary (75%)
What are adenomas encapsulated by?
a surrounding collagen cuff
What are thyroid adenomas composed of?
neoplastic thyroid follicles i.e. Follicular Adenoma
Are adenomas usually functional or non functional?
non-functional
