Thyroid Flashcards
What is the most common tumors of the thyroid gland?
Follicular adenoma
How does the capsule of follicular adenoma differ follicular carcinoma?
Adenoma has a thin but distinct capsule
Carcinoma has a thick capsule
What HLA is associated with subacute de quervain disease?
HLA-Bw35
How does subacute thyroiditis look histologically?
A rim of histiocytes and giant cells replaces the follicular epithelium, giving rise to a granulomatous appearance
How does hashimoto thyroiditis look grossly?
Firm and symmetrically enlarged and can weigh 25 to 250 grams
Lobulation is accentuated due to inter lobular fibrosis
The thyroid has a tan-yellow appearance - due to abundant lymphoid tissue
What are patients with hashimoto thyroiditis at increased risk for?
B-cell lymphoma and plasmacytomas
Sclerosing mucoepidermoid carcinoma
What drug is associated with the development of a goiter?
Lithium
Where is the pigment for hemosiderin vs hemochromatosis?
Hemosiderin will be in the macrophages
Hemochromatosis will be in the follicular epithelium
What drugs can cause the thyroid to turn coal-black?
Tetracyclines (minocyciline)
What is the prognosis of PTC?
> 90% at 20 years
Who gets PTC?
Mainly women in their 3rd and 5th decade
People with sufficient or excess iodine
What syndromes are associated with the development of PTC?
FAP, Cowden syndrome, HNPCC, peutz-jeghers syndrome, ataxia telangiectasia
How does PTC present grossly?
Yellow-white infiltrative mass with evidence of fibrous strands
Can have cyst formation
They are greater than 1.0 cm by definition
How are psammoma bodies formed in PTC?
There is infarction at the tips of papillae attracting calcium that is deposited on dying cells
Where does PTC metastasize to?
Regional lymph nodes
Lungs and bones
What are poor prognostic factors for PTC?
Older age at diagnosis, male sex, extrathyroidal growth, large tumor size
What is the most common variant of follicular adenoma?
Oncocytic follicular adenoma
How does hyper functioning adenoma look histologically?
Follicles are irregularly shaped and frequently show significant variation in size and shape
The cells have vacuolated cytoplasm and uniform, nasally located nuclei
Can have papillary projections into the lumen
What immunostains are best for thyroid origin?
Thyroglobulin, TTF-1 and PAX-8
What immunostains and mutations support the diagnosis of follicular carcinoma?
PPAR-gamma, PAX8-PPARgamma rearrangement, galectin-3, HBME-1 or CITED1
RAS mutation
Galectin-3, HBME-1 or CITED1 cannot differentiate between carcinoma but helps know that it is malignant
What mutations are consistent with PTC?
BRAF and RET/PTC mutations
What variants of follicular carcinoma should you rule out mets as well?
Clear or signet ring cells, mucin production or lacks colloid
Do a thyroglobulin
Or PAX8, TTF-2 (more specific for thyroid), TTF-1 is also positive for lung
What are the microscopic characteristics of PTC?
The nuclear features, irregular and infiltrative border, psammoma bodies, and tumors fibrosis
But only the nuclear features are required for diagnosis
What are the nuclear characteristics of PTC?
Nuclear enlargement, nuclear crowding, chromatin clearing, irregular nuclear outlines, nuclear pseudoinclusions, nuclear grooves
What is the definition of a papillary micro carcinoma?
1 cm or less in diameter and is found incidentally
Do you typically see necrosis in PTC?
No
Which PTC variant is associated with a worse prognosis?
Tall cell variant
