Thyroid Pathology Flashcards
If the thyroid fails to descend from it embryological origin what is this called?
Linguinal thyroid
If the thyroid undergoes excessive descent where is it most likely to be located?
Retrosternal within the mediastinum
What are some non autoimmune causes of thyroiditis?
Palpation
Subacute lymphocytic infiltrate
Infection
What is autoimmune hypothyroidism usually due to?
Hashimoto thyroditis
What is autoimmune hyperthyroidism usually due to?
Graves disease
What are some causes of hyperthyroidism?
Hyper-functioning Nodules or tumours
Graves disease
Graves Disease
10F:1M 20-40years
What causes the hyperthyroidism in graves disease?
Thyroid stimulating immunoglobulin
Acts independently of T3, T4 as well as TSH so isn’t inhibited
Graves disease clinical signs
Diffuse thyroid enlargement
Eye changes - bulging eyes
Pretibial Myxoedema
Why are specific tissues affected in graves disease?
As fibroblasts express TSH recpetors
What is the definition of hypothyroidism?
Low T3 and T4 levels
Hashimotos thyroditis
Middle age women
HLA DR3 / DR5
What can also cause hypothyroidism?
Iodine deficiency
What antibodies are associated with Hashimotos thyroiditis?
Antithyroglobulin
Anti Peroxidase
What does the presence of antibodies in hypothyroidism result in?
Antibody dependant cell mediated cytotoxicity
What to look for in hashimotos thyroiditis?
Diffusely enlarged thyroid Prominent lymphoid infiltrate Follicle atrophy Eosinophilic cytoplasm Possible fibrosis
What can precede hashimotos thyroiditis?
Transient hyperfunction - Hashitoxicosis
What are those with hashimotos thyroiditis at an increased risk of?
B cell Non-Hodgkins Lymphoma
What is a goitre?
Any enlargement of the thyroid gland
What is the most common cause of goitre?
Lack of iodine
Why does a reduced iodine level result in a goitre?
As iodine deficiency results in low T3 and T4
Causes increase in TSH
Stimulates enlargement of the gland in effort to restore T3 and T4 levels
Endemic reasons for diffuse goitre
Iodine deficiency or ingestion of goitregenic substances
Sporadic reasons for diffuse goitre
Inborn errors in metabolism - Dyshormonogenesis
F>M
Most cases are iatrogenic
What does lab analysis of blood samples in goitre usually show?
T3/T4 normal
TSH high
What is an adenoma of the thyroid called?
Follicular adenoma
What are the four main carcinomas of the thyroid called?
Papiliary
Follicular
Medullary
Anaplastic
Which is the most common carcinoma?
Pappiliary 75-85%
How do follicular adenomas clinically appear?
Discrete solitary nodule
Often incidental finding
Produce local symptoms e.g. dysphagia hoarse voice
Under the microscope how do follicular adenomas appear?
Neoplastic thyroid follicles
Encapsulated by surrounding collagen cuff
Why do adenomas usually produce no systemic symptoms?
As they are usually non functional
- some can secrete hormones causing thyrotoxicosis
What carcinoma is related to iodine deficiency?
Follicular carcinoma
What carcinoma is related to ionising radiation?
Papillary carcinoma
Papilliary genetics
MAP kinase pathway activated and RAS mutation
Follicular genetics
P13k/AKT pathway
Anaplastic genetic
p53 and beta catenin mutation
Medullary genetics
Familial link
MEN2 mutation
Papilliary carcinoma
Usually a solitary nodule but can be multi nodular
- often cystic or calcified
Papilliary carcinoma symptoms
Hoarseness dysphagia cough dysopnea - locally advanced
How is a papillary carcinoma usually spread?
Lymphatic metastasis
If a papillary carcinoma is haemotgenously spread where does it usually presen?
Lung
Indicates very late stage
Prognosis in papillary carcinoma
10 year survival is 95%
Follicular carcinoma
Slowly enlarging painless and non functional single nodule
What is main form of metastasis in follicular carcinoma?
Haematogenous
Bones Lungs and Liver
When is a follicular carcinoma difficult to distinguish from an adenoma?
When its minimally invasive and well differentiated
Prognosis of an follicular carcinoma?
10 year survival is 50%
Where is a medullary thyroid carcinoma derived from?
Neuroendocrine C-cells
What are common systemic affects of medullary thyroid carcinoma?
Diarrhoea VIP production
Cushings syndrome ACTH production
What to look for in medullary thyroid tumour?
Congo red stian - amyloidosis
C cell hyperplasia
What mutation indicates familial link and more aggressive potential?
MEN2B
Anaplastic
Undifferentiated and aggresive
Rapid growth and invasion of local neck structures
High mortality
Older patients
