pathology of thyroid Flashcards
what are some embryological abnormalities of thyroid
- failure of descent
- excessive descent
- thyroglossal duct cyst
what is the thyroid composed of
lobules
what is in the centre of each follicle
dense amorphous pink material containing thyroglobulin
thyroid function
- TRH from hypothalamus stimulates release of TSH from cells in anterior pituitary gland.
- TSH binds to TSH receptor on surface of thyroid epithelial cells.
- G proteins activated with conversion of GTP to GDP and production of cAMP.
- cAMP increases production and release of T3 and T4.
- T3 and T4 circulate in bound and free forms
- On release T3 and T4 bind to receptor in target cells
what comes under thryoiditis
hypo and hyperthyroidism
what autoimmune disease presents with hypofunction
hashimoto thyroiditis
what autoimmune disease presents with hyperfunction
grave’s disease
which genes are involved in autoimmune thyroiditis
- CTLA-4
- PTPN-22
which haplotype is autoimmune thyroiditis associated with
HLA
what is Hashimoto’s thyroiditis
gradual destruction of thyroid tissue
- 45-60yrs
- genetic
what is present in Hashimoto’s that characterises it
anti-thyroid antibodies
-CD8 +ve T cells may mediate destruction of thyroid epithelium
signs of hashimoto’s
- thyroid may be enlarged
- prominent lymphoid infiltrate
- thyroid follicles atrophy
- may see progressive fibrosis
what are symptoms and signs due to in hypothyroidism
low levels of T3 and T4
who usually gets hashimoto’s
middle aged women
other causes of hypothyroidism
- iodine deficiency
- drugs
- post therapy
- congenital abnormalities
- in born errors of metabolism
what may hashimoto’s be preceded by
transient hyperfunction
what are people with hashimotos at increased risk of
- other autoimmune disease
- B cell NHL in the thyroid gland (lymphoma)
what antibodies are present in Grave’s disease
- antibodies to TSH receptor, thyroid peroxisomes and thyroglobulin
- anti TSH receptor antibodies
what are symptoms due to in hyperthyroidism
excess T3 and T4
other causes of hyperthryoidism
- thyroiditis
- ectopic production
- Factitious
features of Grave’s
- Hyperthyroidism with diffuse enlargement of the thyroid
- Eye changes (exophthalmos)
- Pretibial myxoedema.
what is Goitre
any enlargement of the thyroid gland
what causes Goitre
-reduced T3/T4 production which causes rise in TSH, stimulating gland enlargement
what is there high levels of in diffuse Goitre
TSH
effects of a multi-nodular goitre
- cosmetic
- airway obstruction
- dysphagia
- compress vessels
adenoma of thyroid gland
follicular adenoma
carcinomas of thyroid gland
- papillary
- follicular
- anaplastic
- medullary
what are the adenomas encapsulated by
Encapsulated by a surrounding collagen cuff
what can adenomas secrete
thyroid hormones - thyrotoxicosis
where are mutations in adenomas
TSHR signalling pathway
who gets thyroid cancer
any age
mainly female
most common carcinoma of thryoid
papillary
where are most of the carcinomas derived from
follicular epithelium
medullary carcinoma is from C cells
what are the environmental associations with carcinoma
Ionising radiation (papillary carcinoma) Iodine deficiency (follicular carcinoma)
metastases of papillary carcinoma
lymph nodes
presentation of papillary carcinoma
- lesion in thyroid gland
- hoarseness
- dysphagia
- cough
- dyspnoea
- sometimes haematogenous spread
features of follicular carcinoma
- slowly enlarging
- painless
- non-functional
what is medullary carcinoma associated with
multiple endocrine neoplasia
what is medullary carcinoma composed of
Composed of spindle or polygonal cells arranged in nests, trabeculae or follicles
associated with amyloid deposition
presentation of medullary carcinoma
- neck mass
- dysphagia
- hoarsenss
- airway compromise
- paraneoplastic syndrome
treatment of medullary carcinoma
total thyroidectomy
is anaplastic carcinoma dangerous/associated with death
yes
