Anatomy
Embryological origin of the thyroid ?
4th endodermal pouch
Anterior midline mass that moves with swallowing ?
Thyroglossal duct cyst
*Can also present as tongue protrusion
Histologic features of papillary thyroid cancer
psammoma bodies, nucelar grooves, orphan annie nucleus (nuclei washed out)
Parafollicular Cells secrete what hormone ?
Calcitonin in response to hypercalcemia
Preferred thioamide in pregnancy ?
PTU
Arterial supply of the thyroid ?
superior art (ext carotid branch)
inferior thyroid art (branch of thyrocervical art off subclavian )
ima art (innominate) to isthmus
Presentation of Reidel Thyroiditis ?
fixed hard painless goiter
IgG4 related systemic dis (AI pancreatitis, RP fibrosis, noninfectious aortitis)
Name (2) indications for FNA of a thyroid lesion
- any lesion > 1 cm w/ high risk features
- hypoechoic
- micocalcifications
- taller than wide
- irregular margins
Name (2) actions of T3/4
- bone growth (synergistic with GH)
- CNS maturation
- inc B1 recptors in the heart
- inc basal metabolic rate via inc Na/K ATPase activity= inc O2 consumption / RR/ body temp
- inc glycogenolysis, gluconeogenesis, lipolysis
What nerve innervates the cricothyroid ?
External branch of Superior laryngeal N
most common nerve injured during a thyroidectomy- runs in close approximation to the superior thyroid art / vein which are sacrificed during thyroidectomy
Where are Delphian nodes located and what are their significance ?
anterior suspensory ligament - first site of spread from thyroid malignancies
Antibodies present in Hashimoto disease?
anti-TPO (antimicrosomal) and antithyroglobulin ab
Management of well differentiated thyroid cancer in pregnancy ?
- if well differentiated papillary or follicular CA : then trt postpartum w/ surgery as indicated
- if poorly differentiated / nodal mets/ distant mets / sig growth or medullary CA ; thyroidectomy can be safely performed during the second trimester
- Anaplastic Ca and or severe compressive symp = immed surgery
Action of 5’deiodinase
converts T4 to T3 in peripheral tissues
What is the Berry ligament and what is it's significance?
posterior suspensory lig of the thyroid ; attaches post thyroid to the trachea, often in close prox to RLN
Most common location of ectopic thyroid tissue ?
Lingual thyroid
Contraindication to radioactive iodine treatment in Graves disease ?
*Bonus 200 for mechanism
proptosis / opthalmopathy
infiltration of retrorbital space by act T cells= sec cytokines (TNF-a/ IFN-y) = inc fibroblast sec hydrophilic GAGs = inc osmotic muscle swelling
-neg nodes
- age < 45
- size < 4 cm
- normal contralat lobe, no invasion
Most common side effects of thioamides?
aplastic anemia and agranulocytosis
What is Lugols's solution and how does it help with resection ?
combination of iodine and k iodine = dec vascularity of the organ making it firmer and easier to resect
What anatomic variation is associated with a non recurrent right laryngeal nerve?
abberent subclavian artery (Ateria lusoria)
Hashimoto patients are at an increased risk for what type of cancer?
NHL - mc B cell tumors
List Bethesda Criteria and treatment ?
Bethesda criteria :
-1 :non diagnostic - repeat FNA
- 2 benign - reapeat exam in 6-12 mon
- 3 atypia or follicular lesion of unknown sig - repeat FNA
- 4 : follicular neoplasm / sus follic neoplasm - need lobectomy for dx
- 5 : sus for malignacy - lobectoby vs total thyroid
- 6 : malignant
Treatment of a thyroid storm ?
BB, lugol’s solution , cooling blankets, steroids (inhibit peripheral conversion of T4 to T3) , thioamide meds
- PTU inhibits peripheral conversion of T4 toT3 and blocks production in thyroid so preferred over methomazole which only does the latter
- acetaminophen should be used to bring down fever (aspirin can increase serum free T4 and T3 concentration )
Presentation of Subacute granulomatous thyroiditis (de Quervian) and treatment ?
self limited disease following a viral pathology w/ inc ESR
*tender painful goiter
trt : pain control (ASA or NSAIDs) , BB, steroids (for severe presentations)
*trt for hyper/hypothyroidism typ not necessary as symptoms are mild and short lived