Thyroid 2 Flashcards
Most common cause of hyperthyroidism in North America?
Grave’s (diffuse toxic goiter)
Women vs men, who is more affected by Grave’s?
women 20-40 y/o
Cause of Grave’s dx?
autoimmune disorders
antibodies against TSH-R
Classic triad of sx of Graves?
sxs of thyrotoxicosis
enlarged neck mass with bruit due to increased flow
exopthalmos
Pathophys of Grave’s dx;
autoantibodies stimulate TSH-receptor, more thyroid hormone is made
Grave’s assc with other autoimmune d/o like?
Addison’s
DM1
pernicious anemia
myasthenia
When testing for hyperthyroidism what lab values do we usually see?
suppressed TSH
elevated T3/T4
***if eye symptoms not present, can do an I 123 uptake scan, an elevated uptake with diffuse enlarged gland confirm Grave’s
What foot findings do we find with Grave’s?
pretibial myxedema
due to deposition of glycosaminoglycans
Tx for Grave’s?
anti-thyroid meds
radio-iodine ablation
thyroidectomy
What anti-thyroid meds used for Grave’s?
PTU 100-300 mg 3x/day
methimazole 10-30 mg 3x/day then 1x/day
How do methimazole and PTU work in pt’s with hyperthyroidism due to Grave’s?
methimazole–> reduce thyroid production by inhibiting thyroid binding iodine
PTU–» same thing, also prevents conversion of peripheral T4 to T3
Which anti-thyroid medication preferred in pregnant pts?
both drugs can cross placenta and inhibit fetal thyroid function
both excreted in breast milk
methimazole assc with congenital aplasia
**PTU has lower risk of trans-placental transfer
Methimazole or PTU for anti-thyroid medication in pregnant pts?
PTU
Side effects of PTU and methimazole?
agranulocytosis and aplastic anemia ***rarely
The catecholamine response of thyrotoxicosis can be mediated by administering what drug?
b-blocker propranolol
**CCBlockers can be used in pts where BB contraindicated
MOA of PTU and methimazole?
inhibit organification of intra-thyroid iodine as well as coupling of iodotyrosine molecules to fomr T3 and T4
Tx of choice for Grave’s dx is US?
radioiodine ablation with I 131
90% success rate
Most pt’’s with hyperthyroidism are candidates for radioiodine ablation, except?
pregnant women
women who are lactating
those with a suspicious nodule
What is thyroid storm?
severe tachycardia fever confusion vomiting adrenergic overstimulation
Tx for thyroid storm?
rapid fluid replacement antithyroid drugs beta blockers iodine solutions steroids
**in life threatening situations, peritoneal vs hemodialysis to get rid of T4 and T3
What is Plummer’s dx?
hyperthyroidism from a single hyperfunctioning nodule that is autonomous (toxic adenomas)
usually seen in younger pts w/recent growth of a nodule
Toxic adenomas, which are usually single solitary nodules that are hyperfunctioning, don’t produce sx of hyperthyroidism until they get to what size?
> 3 cm
**show uptake of iodine, deemed “hot”
**these nodules rarely malignant
Tx for toxic adenomas?
for small nodules can be managed with antithyroid meds or radiodine abalation
larger nodules need surgery
What causes thyroid storm?
abrupt cessation of antithyroid meds infections thyroid/non-thyroid surgery trauma in pts w/underlying thyrotoxicosis following amiodarone administration iodine containing contrasts RAI
Tx for thyroid storm?
b-blocker; propranolol–> decrease hyperthyroid sxs, reduce conversion of T4 to T3
Tylenol for fever
supplemental O2
Lugol’s idoine or sodium ipodate —> decrease iodine uptake and thyroid hormone secretion
PTU–> reduces T4 to T3 conversion
steroids for the adrenals
What % of thyroid nodules are cancerous?
5-15% are cancerous
most are benign
Risk factors for malignancy when evaluating thyroid nodules?
children
males
age < 30, > 60
radiation exposure
US findings of a nodule that are considered suspicious for malignancy?
microcalcifications hypervascular infiltrative margins hypoechoic compared to surrounding tissue shape is taller than its width
What’s the size cutoff for evaluation of thyroid nodules?
nodules <1 cm are usually not followed
Malignancy rates in hot vs cold nodules:
hot nodules; 5-10%
cold nodyles: 15-20%
This cancer accounts for 80% of all thyroid malignancies:
papillary
Most common thyroid cancer?
papillary (80%)
Most common to least common thyroid cancers;
papillary 80%
medullary 6%
Anaplastic 1%
Papillary thyroid cancer tends to affect men or women more?
2;1 women
mean age of presentation 30-40 yrs
Distant mets of papillary carcinoma are rare at presentation, but tend to develop in 20% of pts, where?
lungs*** then
bone
liver
brain
How do we diagnose papillary thyroid Ca?
FNA of thyroid mass or lymph node
after diagnosis made, neck US recommended to look at other half of lobe, and to look for central, lateral neck compartment nodes
Most frequent genetic alteration in papillary thyroid Ca?
PTC-RET proto-oncogene
encodes for a receptor tyrosine kinase
Prognosis of papillary thyroid Ca?
excellent
Most important risk factor for papillary thyroid Ca?
radiation exposure as child
**commonly seen in women, 30-50 y/o
Orphan Annie nuclei and Psammoma bodies seen with which type of thyroid Ca?
papillary
Two distinguishing features of papillary thyroid Ca?
psammoma bodies
orphan Annie nuclei
In this type of thyroid Ca, cells are cuboidal, with abundant cytoplasms, crowded nuclei that show grooving, and intranuclear cytoplasmic inclusions;
papillary Ca—> orphan annie nuclei
These are microscopic calcified deposits of sloughed off cells seen in papillary thyroid Ca;
psammoma bodies
Surgical tx for papillary thyroid Ca?
> 1 cm near total or total thyroidectomy recommended
Scoring systems for thyroid Ca?
AMES; age, mets, extent of primary tumor, size of tumor
AGES
Most important prognostic factor or thyroid Ca?
age at diagnosis (< 40 ass w/better prognosis)
How does papillary ca typically spread?
lymphatics
Tx of papilalry thyroid Ca less than 1 cm?
with no involved LNs
no hx of radiation
lobectomy + isthmusectomy is appropriate
Tx of papillary thyroid Ca >1 cm, or <1 cm with + LNs, hx of radiation?
near or total lobectomy followed by RAI
If someone has a papillary thyroid Ca, and positive central lymph nodes, whats tx?
level VI; central lymph node dissection w/total or near-total thyroidectomy
Follicular thyroid Ca, makes up what % of thyroid Cancers?
10%
What % of thyroid cancers are follicular?
10%
What’s Hurthle cell carcinoma?
variant of follicular type cancer
Men or women affected more by follicular thyroid cancer?
women, 3;1
Which pts are affected by Hurthle cell carcinoma, a variant of follicular carcinoma?
older pts; 60-75
Is follicular ca associated w/radiation exposure?
none
For a histological diagnosis of follicular ca of thyroid what do we need?
follicular cells need to occupy abnormal positions such as capsular, lymphatic, and vascular invasion
two types of follicular ca exist; minimally vs widely invasive
lymph node involvement is unusual in follicular ca (compared to papillary)
Pts w/follicular cancer of thyroid tends to have mets to where?
lung
bone
brain
How does follicular ca of thyroid spread?
HEMATOGENOUSLY
unlike papillary which spreads via LNs
Papillary thyroid cancer spreads lymphatically, while follicular Ca of thyroid spread via:
blood
How do we diagnose follicular ca of thyroid?
FNA is not effective, intra-op frozen section is also not effective
you need to see cellular invasion of the capsule or vascular or lymphatic channels
Follicular Ca of thyroid tends to mets to where?
lytic bone lesions
lung
What is the most important predictor of survival for follicular Ca of thyroid?
age
younger the better
Tx for follicular ca of thyroid?
<2 cm lesion, well contained within 1 thyroid lobe; thyroid lobectomy, isthmusectomy
> 2 cm lesion; total thyroidectomy
**post-surgically you need radio-active iodine ablation with I 131 and long term monitoring of Tg
Hurthle cell is a variant of follicular ca of thyroid seen in elderly pts, how is it different?
more aggressive
worse prognosis than FTC
poor iodine uptake–> RAI less effective
higher rate of recurrence than FTC
This thyroid Ca stems for the parafollicular C cells of the thyroid, located in the upper poles of the thyroid:
medullary thyroid Ca
What causes medullary thyroid Ca?
originates from parafollicular C cells of neural crest origin
How is medullary thyroid cancer inherited?
***80% occur in sporadic form
rest are inherited in AD pattern; MEN2A, MEN2B and familial medullary thyroid cancer
What clinical features are diagnostic of medullary thyroid cancer?
elevated calcitonin levels
presence of a thyroid mass
What gene is affected in MEN syndrome, assc w/medullary thyroid Ca?
RET proto-oncogenes
Prior to considering intervention in pts with medullary thyroid cancer, what needs to happen first?
need to rule out a pheochromocytoma
MEN1?
pituitary adenoma
parathyroid hyperplasia
pancreatic neoplasia
MEN2A?
parathyroid hyperplasia
medullary thyroid Ca
pheochromocytoma
MEN2B?
medullary thyroid Ca
mucosal neuromas
marfan habitus
pheochromocytoma
Tx for medullary thyroid Ca?
at least a total thyroidectomy
Tx for pts with MEN2B RET mutations should have what type of surgery?
prophylactic total thyroidectomy within first year of life
Anaplastic thyroid Ca, makes up what % of thyroid cancers?
1%
1% of all thyroid Ca are what type?
anaplastic
Most aggressive form of thyroid Ca?
anaplastic
An older pt with dysphagia, rapidly expanding neck mass, painful, cervical tenderness, we think of what thyroid Ca?
anaplastic
At the time of diagnosis, 90% of this thyroid Ca has distant mets:
anaplastic
Primary thyroid lymphomas are rare, occurring more frequently in women, how do they present?
hoarseness
dysphagia
fever
rapidly growing goiter
Thyroid lymphomas are almost all non-Hodgkin’s lymphoma of what cell variety?
B cell type
Chemo treatment for lymphoma of thyroid?
CHOP
cyclophosphamide
doxorubicin
vincristine
prednisolone
Tx for lymphoma of thyroid?
CHOP + surgical thyroidectomy
When performing thyroid surgery, where do you make your initial incision?
2 fingerbreadths above clavicle; tranverse incision
lateral borders of the incision should be medial borders of SCM
but the incision can be extended if needed
incision carried thru skin and subQ fat and platysma, superior and inferior skin flaps are raised
anterior jugular vein identified; middle jugular vein cut
Common complications after thyroidectomy?
hypocalcemia from devascularization of parathyroids
hoarseness due to recurrent laryngeal nerve damage
How to avoid hypocalcemia by avoiding parathyroid devascularization?
auto-transplant of 1 mm fragments of saline chilled tissue into pockets made in SCM or brachioradialis muscle
Superior laryngeal nerve damage does what?
internal branch–> sensory to larynx
external branch–> runs close to superior thyroid artery, motor to circothyroid, tenses vocal cords
damage leads to poor volume, fatigue, can’t sing at higher pitches, huskiness
Unilateral recurrent laryngeal nerve injury?
a paralyzed vocal cord, loss of movement from midline
With RAI, when used to treat Grave’s dx, what side effect can we see?
hypothyroidism
Strongest prognostic factor when evaluating someone with thyroid Ca?
AGE
What gives rise to the neural crest cells which cause medullary thyroid Ca?
4th pharyngeal pouch develops into the ultimobranchial bodies early in thyroid development
these neural crest cells then become the parafollicullar C cells
For medullary thyroid cancer, what can we use as a surveillance marker for recurrence following resection?
calcitonin levels
When do we perform a thyroid lobectomy for follicular carcinoma?
lobectomy is sufficient is nodule less than 4 cm
pt is under 45
no signs of distant mets
pt has no personal/family hx of thyroid Ca
**lobectomy allows most of these pts to remain euthyroid post-surgery
Do we perform neck dissections for follicular Ca?
no, nodal involvement is unlikely
disease spreads hematogenously
Surgical tx for medullary thyroid Ca?
documented medullary thyroid Ca needs a total thyroidectomy with b/l level VI central LN dissection
if nodes are positive, needs a lateral neck dissection needed on that side
When do we perform prophylactic thyroidectomy for pts with medullary thyroid Ca associated w/ MEN2A, MEN 2B:
MEN2A–> before 5 year old
MEN2B–> before 1 year old
These are round laminated calcifications in the core of papillae:
psammoma bodies assc/ w papillary thyroid Ca
Describe psammoma bodies seen in papillary thyroid Ca:
round laminated calcifications seen in the core of papillae
Most significant risk factor for papillary thyroid Ca?
radiation exposure as a child
Bethesda classifications after FNA?
1– non-diagnostic–> repeat FNA
2–benign
3–follicular lesion of undetermined significance–> repeat FNA
4–follicular lesion–> genetic eval vs lobectomy
5–suspicious for malignancy–> lobectomy vs thyroidectomy
6–malignant–> total thyroidectomy
How does papillary thyroid cancer spread?
lymphatics
For most pts treatment of Hashimoto’s thyroiditis is handled with levothyroxine in those with hypothyroidism, when do we perform surgery?
pts w/large goiters
pts w/ significant compressive symptoms
sxs refractory to levothyroxine
inability to rule out malignancy
Long-standing neck mass, rapidly enlarges, assc w/ dysphagia, dysphonia, and dyspnea;
anaplastic thyroid Ca
Most pts w/anaplastic thyroid Ca die of what?
superior vena cava syndrome
asphyxiation
exsanguination
Most common location for an ectopic superior parathyroid gland is?
tracheo-esophageal groove
Most common location for an ectopic inferior parathyroid gland is?
thymus
Most common location for a missed parathyroid gland?
normal anatomic location
What are Delphian lymph nodes in thyroid ca?
central compartment lymph nodes; VI
Rotter’s lymph nodes?
located between pec major and pec minor
Most common form of thyroid Ca?
papillary
Cuboidal cells with pale abundant cytoplasm; large crowded nuclei with folded and grooved nuclear margins w/ intranuclear cytoplasmic inclusions:
orphan annie eyes
psammoma bodies
seen in papillary thyroid ca
Hurthle cell is an aggressive variant of follicular Ca, what do we see histologically?
increased number of mitochondria with an enlarged, granular, granular eosinophilic cytoplasm
How do we treat thyroid cancer during pregnancy?
well differentiated papillary/follicular ca without nodal spread, mets, or rapid growth–> post-partum surgery
poorly differentiated Ca like medullary, w/rapid growth, nodal involvements, mets–> surgery 2nd trimester
anaplastic ca, severe compressive sx–> immediate surgery
Radioactive iodine is contraindicated in pregnant pts, why?
I 131 can destroy the fetal thyroid gland
Tx for well differentiated thyroid cancer like papillary during pregnancy?
if no nodal involvement, no mets, not rapidly growing–> post-partum surgery
if nodal involvement, mets, rapidly growing–> 2nd tri
Mainstay of treatment for thyroid lymphoma is?
chemo & radiation
Most thyroid lymphomas are rare, most classified as non-hodgkin’s lymphomas (B cell origin) and almost all develop in setting of?
hashimoto’s thyroiditis
In pts w/suspected thyroid lymphoma, why do we usually see elevated levels of anti-thyroid peroxidase and anti-thyroglobulin antibodies?
strongly assc/w Hashimoto’s
What nerve most likely to be injured during a thyroidectomy?
external branch of superior laryngeal nerve
runs close w/ superior thyroid artery
The thymus and the inferior parathyroids arise from what pouch?
3rd pharyngeal pouch
Ultimobranchial body and superior parathyroids arise from what pouch?
4th pharyngeal pouch
Pts w/severe Grave’s opthalmopathy should be managed with?
thionamides vs total thyroidectomy
**radioactive iodine worsens Grave’s opthalmopathy
DeQuervain’s thyroiditis or subacute thyroiditis typically occurs following what?
viral URI
Tx–> ASA/NSAIDs/ steroids
Tx for thyroid storm?
BB
thionamides
Lugol’s solution
steroids
How big does a thyroid nodule have to be to be biopsied with FNA?
> 1 cm
