Thyroid Flashcards
Types of Thyroid cancer
Please find my Apple
Papillary (70-80%) - most common; best prognosis
Follicular (10-15%)
Medullary (5-8%) - associated with MEN2
Anaplastic (<2%) - poor prognosis
Papillary
Often in young people
Multifocal
Slow growing
Lymphatic spread
Orphan Annie nuclei, psammoma bodies
Follicular cancer
Older patients,
Encapsulated
Haematagenous spread - lung, bone
Diagnosis needs histology FNA unreliable
Medullary cancer
Arises from parafollicular C-cells
Local and nodal spread
Produces calcitonin
MEN 2
Anaplastic cancer
Elderly, rapidly enlarging neck mass
Local invasion
Poor prognosis, palliative treatment
Investigations for thyroid cancer
TFTs - often normal
USS neck - nodules, cervical LN
FNA biopsy (US guided) - Bethesda classification
Calcitonin and CEA if meduallry suspected
CT/MRI - staging and airway
Genetic testing - RET mutations in medullary
Management of thyroid Ca
Papillary and follicular - total thyroid come and radioactive iodine
Medullary - total thyroidectomy and neck dissection (I-131 not taken up by c-cells)
Anaplastic - palliative (surgery, radiotherapy, tracheostomy)
TSH suppression with levothyroxine
Follow up thyroid Ca
Papillary/follciulr - thyroglobulin
Medullary - calcitonin
Prognosis thyroid ca
Papillary: Excellent (10-year survival >90%)
Follicular: Good
Medullary: Variable (worse if MEN2-related)
Anaplastic: Very poor (months)
MRCS flags to think about thyroid cancer
Rapidly enlarging neck mass in elderly → Think anaplastic
Thyroid nodule + family history of MEN → Think medullary, test RET
Cold nodule on scan → More likely malignant
arterial supply to the thyroid
superior thyroid (branch of ECA)
inferior thyroid (branch of subclavian (1st part - thyrocervical trunk)
thryoid ima (10% of population - from brachiocephalic or aorta)
what supplies parathroid glands
inferior thyroid
lymphatic drainage of thyroid
pre-laryngeal, pre-tracheal, upper and lower deep cervical, brachiocephalic
embryology of thyroid
foramen caecum, passes forward and loops beneath hyoid
incomplete descent and closure of foramen and caecum
incoplete descent - lingual or pyramidal thyroid
incomplete closure - thyroglossal cyst (persistent thyroglossal duct)
thyroglossal cyst
incomplete closure/persistent thyroglossal duct
irregular neck lump develops from cells leftover from thyroid development
elevates on swallowing and protrusion of tongue
vertebral level thyroid cartilage
c4
vertebral level hyoid
c3
why does the thyroid move up with deglutition
thyroid s surrounded by pre-tracheal fascia which is attached to thyroid cartilage and hyoid.
when the digastric muscle contracts, it pulls the hyoid bone upward which pulls the thyroid cartilage which pulls the pretracheal fascia and its contents
venous drainage of thyroid
superior and middel thyroid vens into the IJV
inferior thyroid vein into brachiocephalic vein
suprahyoid muscles vs infrahyoid muscles
suprahyoid = digastric and mylohyiod
infrahyoid = sternothyroid, thyrohyoid, sternohyoid, omohyoid
supra - elevates larynx, open mouth ans stbilise tongue
infra - depresses larynx after swallowing
ligamanet attaching thyroid to larynx
ligament of berry
It is a thickening of the pretracheal fascia that anchors the thyroid gland to the cricoid cartilage and upper trachea.
cricoid cartilage
A complete ring of cartilage at C6 level.
Lies just below the thyroid cartilage.
Forms part of the laryngeal skeleton.
commonly injured nerves during thyroidectomy
external laryngeal nerve (close to superior thyroid artery)
recurrent laryngeal nerve (close to inferior thyroid artery and laigament of berry posterior to the gland)
lateral ligature of inferior thyroid artery may cause ischaemia of the cervical sympathetic chain
type of thyroid cancer that spreads via lymphatics
papillary
cell origin of medullary carcinoma
parafollicular c-cells
late complications of thyroidectomy
hypothyroidism
hypocalcaemia
location of parathyroid glands
posterior aspect of the thyroid, 2 each side
function of parathyroid gland
calcium homesostasis
embryology of parathyroid glands
inferior parathyroid from 3rd branchial arch (with thymus)
superior from the 4th branchial arch
blood supply parathyroif
inferior thyroid artery (1st subclavia, thyrocervical trunk)
