SDL 8: tumors of thyroid gland

a result of metastasis

secondary thyroid tumors are

Follicular adenomas outnumber thyroid carcinomas by a ratio of nearly 10:1

most common type of thyroid tumor

thyroid cancer

diagnosed at a younger age in women than most other adult cancers

-external radiation to the cervical region and iodine deficiency

most significant risk factors for thyroid neoplasm

follicular and anaplastic adenomas

iodine deficiency is an especially associated risk factor for what thyroid tumors?

follicular cells

-C cells (parafollicular cells)

two cell types that give rise to thyroid carcinomas:

-papillary, follicular, and anaplastic carcinomas

follicular cells give rise to what thyroid cancers

MTC

C cells give rise to what thyroid carcinoma

increase

serum TSH levels ________ when thyroid nodule is malignant

-ultrasound provide more anatomic detail than physical exam

-need FNA to check malignancy

imaging used to assess thyroid noddules

mostly solid, hyperechoic nodules

US findings of malignant thyroid nodules

follicular adenoma and follicular carcinoma

what thyroid cancers can FNA not diagnose?

follicular adenoma

benign encapsulated tumor with follicular cell differentiation

-seen surrounded by a thin fibrous capsule

presence of an intact, well formed capsule encircling the tumor

hallmark of follicular adenoma

normofollicular adenoma

most common subtype of follicular adenoma

microfollicular adenoma

smalll, closelly packed follicles

trabecular adenoma

subtype of follicular adenoma with cords or trabeculae with few follicles

solid (embryonal) adenoma

follilcular adenoma composed of solid sheets

no

are toxic adenomas and toxic multinodular goiters precursors to folllicular carcinoma?

follicular adenoma

-US shows solitary nodule

-most are euthhyroid

-RAIU shows a cold nodule (hot if bigger)

papillary thyroid carcinoma

slow growing tumor characterized by papillary pattern with distinctive nulcar features

papillary thyroid carcinoma

tumor is pale white with cystic degeneration

-clear/empty appearance---> ground glass or orphan annie eye nuclei

nuclear morphology of pappillary carcinoma

orphan annie eye nuclei

Seen in Papillary Carcinoma of the Thyroid. Enlarged thyroid cells with ground glass nuclei

intranuclear "pseudo-inclusion"

intranuclear grooves of papilllary carcinoma

Psammoma bodies

calcified struuctures in papilllary carcinoma

-indicates lymphatic invasion

follicular variant

most common variant of papillary carcinoma

-has characteristic nuclei, but totally follicullar architecture

BAY 43-9006 (Sorafenib)

-kinase inhibitor with activity against BRAF--> papillary carcinoma

papillary carcinoma

BRAF mutations, RET rearrangement indicates

Sunitinib

oral, multitargeted RET tyrosine kinase inhibitor that has been developed as targeted therapy for papillary thyroid carcinomas

asymptomatic thyroid mass or an enlarged lymph nodule

-no signs of hypo or hyper thyroidism

presentation of papillary carcinoma

solid and hypoechoic

malignant nodules on sonography appear

cold

hot or cold masses in pap carcinoma?

excellent

prognosis of papillary carcinoma

follicular thyroid carcinoma

second most common malignant thyroid tumor

follicular thyroid

gross pathology: solitary nodules well circumscribed with thick white fibrous capsule

-nodules are yellow tan on cut section

FTCs are differentiated from benign follicular adenomas by tumor capsule invasion and/or vascular invasion

how is follicular carcinoma differentiated from follicular adenoma on groww pathology?

indicates follicular carcinoma

-PI3K/AKT pathway mutations

-RAS mutations

PTEN mutations

PTEN

Inactivating somatic mutations of ____ gene are found in 27% of follicular carcinomas

PAX8-PPAR rearrangement

fusion transcript associated with follicular carcinoma

asymptomatic, painless solitary thyroid nodule

-nodule is fixed to surrounding tissue

presentation of follicular carcinoma

cold nodule

RAIU finding on follicular carcinoma

-FTC metastases are hematogenous, not lymphatic, and are direct to the bones, shoulder, pelvic girdles, sternum, and skull

how does follicular carcinoma differ from papillary carcinoma?

anaplastic thyroid carcinoma

the most aggrressive thyroid malignancy?

anaplastic carcinoma

cancer may derive from papillary or follicular types; peak incidence in 6th and 7th decade of life

anaplastic carcinoma gross pathology

highly necrotic and hemorrhagic solid mass; tan to brown cut

HUGE

squamous pattern, spindle pattern, giant cell type

what are the three histologic patterns of aanaplastic thyroid carcinoma?

anaplastic carcinoma

presentation: rapidly enlarging neck mass, rapidly lethal clinical course

medullary thyroid carcinoma

neuroendocrine neoplasms derived form the parafollicular (C cells)

calcitonin

medullary thyroid carcinomas secrete

medullary thyroid carcinoma

amyloid stains positively with calcitonin immunostains

RET protooncogene

key molecule associated with the development of MTC

RET oncogene

in mosst pts with MEN2A or MEN 2b have activatinng point mutations in

Sunitinib

RET kinase inhibitor currently in clinicla trails for treatment of MTC

asymptomatic thyroid nodule

-larger ones cause difficulty swallowing

-may cause hoarseness

-flushing and diarrhea from increased electrolyte secretion secondary to high calictonin

presentation of medullary thyroid carcinoma

elevated basal serum calcitonin levels

diagnostic lab values of MTC

thyroglobulins

primary biochemical marker for pts with differentiated thyroid cancers

predicts te absencce of recurrence during long term follow up!

undetectable postoperative Tg predicts what prognosis of thyroid cancer?