Flashcards in L2 Pathology of Thyroid Deck (33):
What are some effects of thyroid hormones ?
1. Stimulate the contraction of heart
2. Increase oxygen consumption and heat production in all tissue
3. Stimulate gut motility
4. Important of CNS development
5. Stimulate production of structural proteins
What are the disorders of thyroid ?
3. Diffuse/nodular/multi-nodular goiter
4. Thyroid cancer (adenoma/ carcinoma )
6. Congenital > thyroglossal duct cyst
What is thyroglossal duct cyst ?
It is a fluid-filled cyst occurs anywhere along the thyroglossal duct in the midline
Most commonly near hyoid bone or attached to soft tissue
What is the structure of the cyst ?
1. Made of squamous or respiratory type epithelium
2. Variable amount of thyroid tissue
What type of tumor can develop in these cyst ?
What are the main causes of hyper?
1. Abnormal stimulator of the thyroid ( grave disease )
2. Intrinsic disease of thyroid ( toxic multi-nodular goiter / functional thyroid adenoma )
3. Abnormal secretion of TSH ( pituitary adenoma)
What are the triad for people with grave disease ?
3. Peri-tibial myxedema / clubbing
What are the gross and microscopic features of thyroid in grave disease ?
- moderately enlarged
- firm and beefy red ( due to increased vascularity )
- lymphoid infiltrate
- glands show hyperplasia of :
* acinar epithelium
* tall columnar cells
* papillary folds
What is the cause of exophthalmus and peri-tibial myxedema ?
1. Lymphocytic infiltrate
2. Glycosaminoglycans ( hyaluronic acid ) deposition
What are the causes of hypothyroidism (myxedema ) ?
1. Iodine deficiency
2. Hashimoto disease
4. Radiation / surgery
What are the types of thyroiditis ?
1. Acute thyroiditis ( bacterial or fungal infection )
2. Chronic autoimmune thyroiditis ( Hashimoto disease )
3. Granulomatous thyroiditis ( viral infection ):
- de queen
- giant cell thyroiditis
4. Subacute lymphocytic thyroiditis ( post-partum )
5. Riedel thyroiditis ( IgG-4 related - thyroid fibrosis )
What is the underlying cause of Hashimoto disease ?
It is an autoimmune disease caused by ab against :
Due to HLA B8 / DR5
What are the gross and microscopic features of Hashimoto disease?
- firm diffuse goiter
- follicle atrophy with lymphocyte
- hurthle cells ( eosinophilic epithelial cells )
What is the pathological mechanisms in Hashimoto disease ?
1. CD8+ cytotoxic T cell mediated killing
2. Cytokine mediated cell death ( interferon will activate more cells / Macrophages )
3. Binding of antithyroid antibodies then ADCC
What is the genetic cause of granulomatous thyroiditis?
What is the microscopic features of granulomatous thyroiditis ?
1. Patchy Micro abscess
2. Granulomas with giant cells
What is happening in the iodine deficiency goiter ?
Hyperplasia of the epithelium of the gland and appearance of less active areas that will be compressed by the hyper-plastic areas
What will lead to multi-modular goiter in iodine deficiency goiter ?
The tracts of fibrosis that will separate areas
What are the features of thyroid neoplasms ?
1. Most are solitary and benign
2. Low mortality rate
3. May be functional ( hot )
What are the main types of thyroid cancer ?
1. Papillary carcinoma ( most common )
2. Follicular adenoma
3. Follicular carcinoma
4. Anaplastic carcinoma
5. Medullary carcinoma ( least )
What is the gross and microscopic features of follicular adenoma ?
- solid mass with fibrous capsule that is not breached
- centre may contain areas of hemorrhage and cystic changes
- compacted follicles
- lined with epithelial cells that show hyperchromtism
- little collied
- rarely, it can produce T3 and T4 so considered as hot
Which age is usually affected by each type of thyroid cancer ? What is the prognosis ?
1. Papillary carcinoma ( young adults >45 ) ( only 5% is familial )
2. Follicular ( young middle < 45 )
3. Anaplastic ( elderly / very poor prognosis )
4. Medullary ( elderly / can be familial which will be more aggressive )
What are the possible risk factors of papillary carcinoma ?
1. High iodine intake
3. Genetic factors
4. Somatic mutations
What are the different somatic mutations that increase the risk of papillary carcinoma?
1. Familial granulomatous polyposis
2. Somatic rearrangement of RET proto-oncogenes on chromosome 10
3. Chromosomal rearrangement of RET or NTRK1
4. Mutations in BRAF
What is the gross and microscopic features of papillary carcinoma ?
1. Non-encapsulated infiltrative mass
2. Firm and whitish due to fibrosis
1. Epithelial papillary projections
2. Psammoma bodies
3. Characteristic nuclei with central clear mass ( orphan Annie nuclei )
Through what does the papillary and follicular carcinoma metastasize ?
1. Papillary > lymphatics to cervical lymph node
1. Follicular > blood vessels to bones and lungs
Why follicular carcinoma has god prognosis ?
As many tumors retain their ability to uptake the I311 ( radiotherapy )
What are the possible genetic causes underlying follicular carcinoma?
- RAS mutations
- PAX8-PPAR gamma 1 rearrangement
What are anaplastic carcinoma ? and what is the microscopic features ?
- It is poorly differentiated adenocarcinoma from thyroid epithelium
- It has many histological appearances but the commonest is :
* giant cell
* spindle cell
Why anaplastic carcinoma has very poor prognosis ?
Due to rapid local invasion
What is medullary carcinoma ?
Derived from C cells
What does medullary carcinoma secrete ?