22 Thyroid Flashcards

1
Q

Embryological origin of thyroid

A

1st and 2nd pharyngeal arches

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2
Q

Origin of superior thyroid artery

A

First branch off external carotid

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3
Q

Origin of inferior thyroid artery

A

Of thryocervical trunk

Supplies both the inferior and superior parathryoids

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4
Q

Ima artery

A

From innominant or aorta
Supplies the thyroid isthmus
1% of patients

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5
Q

Superior and middle thyroid veins drain to:

A

Internal jugular vein

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6
Q

Inferior thyroid vein drains to:

A

Innominante vein

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7
Q

Superior laryngeal nerve

A

Motor to cricothyroid muscle
Runs lateral to thyroid lobes
Runs close to superior thyroid artery
Injury - loss of projection and easy voice fatigability

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8
Q

Recurrent laryngeal nerve

A

Motor - all of larynx except cricothyroid muscle
Runs posterior to thryoid lobe in tracheoesophageal groove
Can run with inferior thyroid adrtery
Left RLN - around aorta; Left LLN - around innominate artery
Injury - hoarseness; bilateral injury can obstruct airway

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9
Q

Liagment of berry

A

Posterior medial suspensory ligament close to RLNs

Needs careful dissection

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10
Q

Peroxidases

A

Link iodine and tyrosine together

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11
Q

Deiodinases

A

Separates iodine from tyrosine

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12
Q

Most sensitive indicator of thyroid gland function?

A

TSH

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13
Q

Tubercules of Zuckerland

A

Most lateral, posterior extension of thyroid tissue
Rotate medially to find RLNs
Leave behind in a subtotal thyroidectomy

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14
Q

Post-thyroidectomy stridor

A
Incisional hematoma (open neck and remove emergent)
Bilateral RLN injury (emergent tracheostomy)
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15
Q

Thyroid storm

A

Sx: Tachycardia, fever, numbness, irritability, vomiting, diarrhea, HOCF
Undiagnosed Graves’ disease
Precipitants - anxiety, excessive gland palpation, adrenergic stimulants
Tx: B-blockers, PTU, Lugol’s solution, cooling blankets, oxygen, glucose

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16
Q

Wolff-Chaikoff effect

A

High doses of iodine (Lugol’s solution, potassium iodide) - inhibits TSH action on thyroid and inhibits organic coupling of iodide.
Results in less T3 and T4 release.
Transitory effect.

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17
Q

Best initial test for asymptomatic thryoid nodule?

A

FNA

Thyroid function tests

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18
Q

Thyroid FNA shows: Follicular cells

A

Lobectomy (10% CA risk)

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19
Q

Thyroid FNA shows: THyroid cancer

A

Thyroidectomy or lobectomy

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20
Q

Thyroid FNA shows: Cyst fluid

A

Drain fluid

If recurs or is bloody - lobectomy

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21
Q

Thyroid FNA shows: collid tissue

A

Most likely to be a colloid goiter - low chance of malignancy (<1%)
Tx: thyroxine, lobectomy if it enlarges

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22
Q

Thyroid FNA shows: normal thyroid tissue and TFTs are elevated

A

Solitary toxic nodule
Tx:
- Asymptomatic can monitor
- Symptomatic - PTU and 131I

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23
Q

Thyroid FNA shows: Indeterminant

A

Get radionuclide study

  • Hot nodule - PTU and 131I if symptomatic
  • Cold nodule - lobectomy
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24
Q

Goiter

A

Any abnormal enlargemetn
MCC - iodine deficiency
Operate if airway compression or suspicious nodule
Tx: subtotal or total thyroidectomy

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25
Q

Substernal goiter

A

Usually secondary - vessels originate from superior and inferior thyroid arteries
Primary - rare, vessles originate from innominate artery

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26
Q

Mediastinal thyroid tissue

A

Inferior extension of normally placed gland

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27
Q

Lingual thyroid

A

Thyroid tissue that persists at foramen cecum
Sx: dysphgia, dyspnea, dysphonia
2% malignancy risk
Tx: thryoxine suppression, abolish with I131

28
Q

Thyroglossal duct cyst

A

Moves upward with swallowing
Risk for infection and malignancy
Tx: Sistrunk procedure (remove midportion of hyoid bone with thyroglossal duct cyst)

29
Q

Treatment for young patients, small goiters and mild T3/T4 elevations?

A

Propylthiouracil

Methimazole

30
Q

Treatment for pregnant patients?

A

PTU

31
Q

PTU (thioamide)

A

Inhibits peroxidases, inhibits peripheral conversion

AE: aplastic anemia, agranulocytosis

32
Q

Methimazole

A

Inhibits peroxidases

AE: creatinism, aplastic anemia, agranulocytosis

33
Q

Radioactive iodine (131I)

A

Poor surgical risk or unresponsive to PTU

CI - children, pregnancy

34
Q

Graves disease

A

Exophthalmos, pretibial edema, afib, heat intolerance, thirst, increase appetite, weight loss, sweating, palpitations
IgGG antibodies to TSH receptor
Dx: decreased TSH, increased T3/T4; increased 123I uptake, diffusely
Tx: Thioamides, 131I, thyroidectomy

35
Q

Operating on graves disease?

A

Indication - suspicious nodule, non-compliant patient, recurrence after medical therapy, children, pregnancy (not controlled with PTU)
Preop prep - PTU until euthyroid, B-blocker, Lugol’s solution (decrease friability and vascularity)
Op - bilateral subtotal or total thyroidectomy

36
Q

Toxic multinodular goiter

A

Women, >50yo
Sx: tachycardia, wt loss, insomnia, airway compromise (can be precipitated by contrast dye)
Hyperplasia secondary to chornic low-grade TSH stimulation
Tx: Surgery (subtotal or total thyroidectomy), 131I if elderly and frail

37
Q

Single toxic nodule

A

Women, younger, usually >3cm if symptomatic, functions autonomously
Dx: Thyroid scan (hot nodule)
Tx: Thioamides and 131I, lobectomy if medical tx infeffective

38
Q

Hashimoto’s

A

Hyopthyroidism
Enlarge gland, painless, chronic thyroiditis
History of childhood XRT
Humeral and cell-mediated autoimmune disease (microsomal and thyroglobulin antibodies)
Tx: Thyroxine, partial thyroidectomy if continues to grow, nodules appear or compression symptoms

39
Q

Bacterial thyroiditis

A

Contiguous spread from URI
normal thyroid function test, fever, dysphagia, tenderness
Tx:
- ABX
- Lobectomy (R/O cancer for unilateral swelling)
- Total thyroidectomy (persistent inflammation)

40
Q

DeQuervain’s Thyroiditis

A

Hyperthyroid > hypothyroid
Viral URI precursor
Elevated ESR
Tx: Steroids, ASA
- Lobectomy (R/O cancer for unilateral swelling)
- Total thyroidectomy (persistent inflammation)

41
Q

Riedel’s fibrous stomra

A
Woody, fibrous compartment - invasive
Need biopsy to R/O CA/lymphoma
Compression symptoms
Tx:
- Steroids, thyroxine
- Isthmectomy or trachesotyom for airway symptoms
- RLNs at great risk if resected
42
Q

Thyroid nodule - worrisome for malignancy

A
Solid
Solitary
Cold
Slow growing
Hard
Male
Age >50yo
PRevious neck XRT
MEN IIa or IIb
43
Q

Follicular adenoma

A

Colloid, embryonal, fetal
No increased cancer risk
Lobectomy to prove it is an adenoma

44
Q

Papillary thyroid carcinoma

A

Best prognosis
Childhood XRT
Lymphatic spread first - but prognosis based on local invasion
Pathology - psammoma bodies, oprhan annie nuclei

45
Q

Treatment of papillary thyroid carcinoma - minimal/incidental (<1cm)

A

Lobectomy

46
Q

Treatment of papillary thyroid carcinoma - Bilateral lesion, multicentricity, history of XRT, positive margins or tumors >1cm

A

Total thyroidectomy

47
Q

Treatment of papillary thyroid carcinoma - clinically positive cervical ndoes

A

Ipsilateral MRND

48
Q

Treatment of papillary thyroid carcinoma - extrathyroidal tissue involvement

A

Ipsilateral MRND

49
Q

Treatment of papillary thyroid carcinoma - metastatic disease, residual local disease, positive LN or capsular invasion

A

131I

4-6 weeks after surgery

50
Q

When do you use XRT in treatment of papillary thyroid carcinoma?

A

Unresectable disease not responsive to 131I

51
Q

Enlarged lateral neck lymph node with normal-appearing thyroid tissue?

A

Papillary thyroid CA with lymphatic spread
Total thyroidectomy and MRND
131I 4-6 weeks after surgery

52
Q

Follicular thyroid carcinoma

A

Hematogenous spread - bone
FNA shows follicular cells
Tx: Lobectomy
- Adenoma/folliclar cell hyperplasia - done
- Follicular CA - total thyroidectomy and 131I (if >1cm or extrathyroidal)

53
Q

Medullary thyroid carcinoma

A
MEN IIa or IIb
Parafollicular C cells
Path - amyloid deposition
Screen for hyperPTH and Pheo
Lymphatic spread
Tx: total thyroidectomy with central neck node dissection
54
Q

What is the first manifestation of MEN IIa or IIb?

A

Diarrhea

55
Q

Where does medullary thyroid cancer spread to?

A

Lung, liver, bones

56
Q

Prophylaxtic thyroidectomy and central node dissection for MEN - when?

A

MEN IIa - 6yo

MEN IIb - 2yo

57
Q

Hurthle cell carcinoma

A

Most benign
Bone and lung mets
Tx: Total thyroidectomy and MRND for clinically positive nodes

58
Q

Anaplastic thyroid cancer

A

Most aggressive

Tx: total thyroidectom, palliative thyroidectomy or chemo-XRT

59
Q

XRT effective for:

A

Papillary, follicular, medullary and Hurthle cell thyroid CA

60
Q

131I effective for:

A

Papillary and follicular thyroid CA only

61
Q

Indications for 131I

A

Recurrent CA
Primary inoperable tumors due to invasion
Tumars >1cm or extrathyroidal disease (extra-capsular invasion, nodal spread or mets)

62
Q

I131 AE

A
Sialoadenitis
GI symptoms
Infertility
BM suppression
Parathyroid dysfunction
Leukemia
63
Q

Gene Mutations: Papillary Thyroid Carcinoma

A

BRAF

64
Q

Gene Mutations: Medullary Thyroid Carcinoma

A

RET-1

65
Q

Gene Mutations: Anaplastic Thyroid Carcinoma

A

p53

66
Q

Gene Mutations: Follicular thyroid carcinoma

A

PAX8/PPAR-gamma