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ABSITE 2019-RM > Chapter 22: Thyroid > Flashcards

Chapter 22: Thyroid Flashcards

1
Q

Embryology: thyroid

A

Forms from the 1st and 2nd pharyngeal arches (not from pouches)

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2
Q

Released from the hypothalamaus; acts on the anterior pituitary gland and causes release of TSH

A

Thyrotropin-releasing factor (TRF)

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3
Q

Released from the anterior pituitary gland; acts on the thyroid gland to release T3 and T4 (through a mechanism that involves increased cAMP)

A

Thyroid-stimulating hormone (TSH)

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4
Q

What controls the release of TRF and TSH?

A

TRF and TSH release are controlled by T3 and T4 through a negative feedback loop

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5
Q

1st branch off the external carotid artery

A

Superior thyroid artery

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6
Q

Off thyrocervical trunk; supplies both the inferior and superior parathyroids

A

Inferior thyroid artery

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7
Q

Where do you ligate the inferior thyroid artery?

A

Ligate close to thyroid to avoid injury to parathyroid glands with thyroidectomy.

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8
Q

Occurs in 1%

- Arises form the innominate or aorta and goes to the isthmus

A

Ima artery

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9
Q

Drain into internal jugular veins

A

Superior and middle thyroid veins

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10
Q

Where do superior and middle thyroid veins drain?

A

Internal jugular vein

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11
Q

Where does the inferior thyroid vein drain?

A

Innominate vein

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12
Q

Nerve:

  • Motor to cricothyroid muscle
  • Runs lateral to thyroid lobes
  • Tracks close to superior thyroid artery but is variable
  • Injury results in loss of projection and easy voice fatiguability (opera singers)
A

Superior laryngeal nerve

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13
Q

Nerve:

  • Motor to all of larynx except cricothyroid muscle
  • Runs posterior to thyroid lobes in the tracheoesophageal groove
  • Can track with inferior thyroid artery but variable.
A

Recurrent laryngeal nerve

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14
Q

Where does recurrent laryngeal nerve run?

A

Posterior to thyroid lobes in the tracheoesophageal groove

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15
Q

Path of right vs left recurrent laryngeal nerve

A

Left RLN: loops around aorta

Right RLN: loops around innominate artery

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16
Q

What can happen with injury to the recurrent laryngeal nerve?

A

Injury results in hoarseness; bilateral injury can obstruct airway -> need emergency tracheostomy

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17
Q

What can happen with injury to the superior laryngeal nerve?

A

Injury results in loss of projection and easy voice fatiguability (opera singers)

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18
Q

Nerve:

  • Occurs in 2%
  • More common on the right
A

Non-recurrent laryngeal nerve

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19
Q

Nerve: risk of injury is higher for this nerve during thyroid surgery

A

Non-recurrent laryngeal nerve

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20
Q

Posterior medial suspensory ligament close to recurrent laryngeal nerves; need careful dissection.

A

Ligament of Berry.

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21
Q

Stores T3 and T4 in colloid

A

Thyroglobulin

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22
Q

Ratio of plasma T4:T3

A

15: 1.
- T3 is the more active form (is tyrosine + 3 iodine) bc it is more free in plasma 0.5% of total
- T4 is less active and cannot be made in periphery (tyrosine +4 iodine) bc less free in plasma 0.02% of total

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23
Q

Tyrosine + 3 iodine

A

T3

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24
Q

How is most T3 produced?

A

Most T3 is produced in the periphery from T4 to T3 conversion by deiodinases

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25
Q

Link iodine and tyrosine together

A

Peroxidases

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26
Q

Separate iodine from tyrosine

A

Deiodinases

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27
Q

Thyroid hormone transport; binds the majority of T3 and T4 in circulation

A

Thyroxine-binding globulin

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28
Q

Most sensitive indicator of gland function

A

TSH

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29
Q

Most lateral, posterior extension of thyroid tissue

- Rotate medially to find recurrent laryngeal nerves.

A

Tubercles of Zuckerkandl

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30
Q

What portion of the thyroid is left behind with subtotal thyroidectomy?

A

Tubercles of Zuckerkandl secondary to proximity to RLNs.

- Tubercles of Zuckerkandl: most lateral, posterior extension of thyroid tissue.

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31
Q

Produce calcitonin

A

Parafollicular C cells

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32
Q

Goals of thyroxine treatment

A

TSH levels should fall 50%

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33
Q

Long term side effect of thyroxine treatment

A

Osteoporosis

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34
Q

Treatment for post-thyroidectomy stridor

A

Open neck and remove hematoma emergently -> can result in airway compromise, can also be due to bilateral RLN injury -> would need emergent tracheostomy.

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35
Q

Symtoms: Tachycardia, fever, numbness, irritability, vomiting, diarrhea, high-output cardiac failure (MCC death)

A

Thyroid storm

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36
Q

MCC death in thyroid storm

A

High output cardiac failure

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37
Q

When is thyroid storm MC post-operatively??

A

MC after surgery in patient with undiagnosed Grave’s disease

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38
Q

Treatment: thyroid storm

A

Beta-blockers, PTU, Lugol’s solution (KI), cooling blankets, oxygen, glucose.
- Emergent thyroidectomy rarely indicated.

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39
Q

First line treatment of thyroid storm

A

Beta-blockers

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40
Q
  • Very effective for thyroid storm
  • Pt given high doses of iodine (Lugol’s solution, potassium iodide), which inhibits TSH action on thyroid and inhibits organic coupling of iodide, resulting in less T3 and T4 release
A

Wolff-Chaikoff effect

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41
Q

90% of thyroid nodules are..

A

Benign and in females

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42
Q

Best initial test for a thyroid nodule

A

FNA and thyroid function tests

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43
Q

Tx: FNA shows follicular cells

A

Lobectomy (10% CA risk)

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44
Q

Tx: FNA shows thyroid CA

A

Thyroidectomy or lobectomy and appropriate treatment

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45
Q

Tx: FNA shows cyst fluid

A

Drain fluid.

- If it secures or is bloody -> lobectomy

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46
Q

Tx: FNA shows colloid tissue

A

Most likely colloid goiter; low chance of malignancy (

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47
Q

Tx: FNA shows normal thyroid tissue and TFTs are elevate

A

Likely solitary toxic nodule.

- Tx: if asymptomatic can just monitor; PTU and I(131) if symptomatic.

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48
Q

FNA: % determinate vs % indeterminate

A
  • Determinant in 80% -> follow appropriate treatments.

- Indeterminate in 20% -> get radionuclide study

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49
Q

If FNA is indeterminate?

A

Get radionuclide study.
Will show..
- Hot nodule vs Cold nodule

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50
Q

Tx: hot nodule on radionuclide study

A

If asymptomatic can monitor. PTU and I(131) is symptomatic.

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51
Q

Tx: cold nodule on radionuclide study

A

Lobectomy (more likely malignant than hot nodule)

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52
Q

Any abnormal thyroid enlargement

A

Goiter

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53
Q

Most identifiable cause of goiter

A

Iodine deficiency

- Tx: iodine replacement

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54
Q

Diffuse thyroid enlargement without evidence of functional abnormalities

A

Nontoxic colloid goiter

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55
Q

When would you operate on goiter?

A

Unusual to have to operate unless goiter is causing airway compression or there is a suspicious nodule.
- Tx: subtotal or total thyroidectomy for symptoms or if suspicious nodule; subtotal has decreased risk of RLN injury.

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56
Q

Goiter:

  • Usually secondary (vessels originate from superior and inferior thyroid arteries)
  • Primary substernal goiter - rare (vessels originate from innominate artery)
A

Substernal goiter

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57
Q

Most likely from acquired disease with inferior extensions of a normally placed gland (e.g. substernal goiter)

A

Mediastinal thyroid tissue

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58
Q
  • Occurs in 10%

Extends form the isthmus toward the thymus

A

Pyramidal lobe

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59
Q

Thyroid tissue that persists in foramen cecum at the base of the tongue.

  • S/S: dysphagia, dyspnea, dysphonia
  • 2% malignancy risk
  • Is the only thyroid tissue in 70% of patients who have it
A

Lingual thyroid

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60
Q

Tx: lingual thyroid

A

Thyroxine suppression, abolish with I(131)

- Resection if worried about CA or if it does not shrink after medical therapy.

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61
Q
  • Classically moves upward with swallowing

- Susceptible to infection and may be premalignant

A

Thyroglossal duct cyst

Tx: resection -> need to take mid portion or all of hyoid bone alone with the thyroglossal duct cyst (Sistrunk procedure)

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62
Q

Treatment of thyroglossal duct cysts

A

Sistrunk procedure:

- Resection -> take mid portion or all of hyoid bone along with the thyroglossal duct cyst.

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63
Q

Indications for propylthiouracil (PTU) and methimazole

A

Young patients.
Small goiters.
Mild T3 and T4 elevation.

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64
Q
  • Safe in pregnancy
  • Inhibits peroxidases and prevents iodine-tyrosine coupling
  • Side effects: aplastic anemia, agranulocytosis (rare)
A

PTU (thioamides)

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65
Q
  • Inhibits peroxidases and prevents iodine-tyrosine coupling

- Side effects: cretinism in newborns (crosses placenta), aplastic anemia, agranulocytosis (rare)

A

Methimazole

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66
Q
  • Good for patients who are poor surgical risks or unresponsive to PTU
  • Do not use in children or during pregnancy -> can traverse placenta
A

Radioactive iodine (I-131)

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67
Q
  • Good for cold nodules, toxic adenomas or multi nodular goiters not responsive to medical therapy, pregnant patients not controlled with PTU, compressive symptoms
A

Thyroidectomy

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68
Q

Best time to operate on thyroid during pregnancy.

A

2nd trimester: decreased risk of teratogenic events and premature labor.

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69
Q

Operation can leave the patient euthyroid

A

Subtotal thyroidectomy

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70
Q

Symptoms: women, exophthalmos, pretrial edema, atrial fibrillation, heat intolerance, thirst, increased appetite, weight loss, sweating, palpitations

A

Graves’ disease

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71
Q

MCC hyperthyroidism (80%)

A

Graves’ disease

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72
Q

What is the cause of Grave’s disease?

A

Caused by IgG antibodies to TSH receptor (long-acting thyroid stimulates [LATS], thyroid-stimulating immunoglobulin [TSI])

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73
Q

Decreased TSH.
Increased T3 and T4.
LATS level.
Diffuse increase in 123-i uptake (thyroid scan).

A

Graves’ disease

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74
Q

Tx: Graves’ disease

A

Thioamides (50% recurrence)
131-i (5% recurrence)
Thyroidectomy if medical therapy fails.

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75
Q

Graves’ disease: pre-op preparation

A

PTU until euthyroid. B-blocker. Lugol’s solution for 14 days to decrease friability and vascularity (start only after euthyroid).

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76
Q

Graves’ disease: operation

A

Bilateral subtotal (5% recurrence) or total thyroidectomy (need lifetime thyroxine replacement)

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77
Q

Graves’ disease: indications for surgery

A

Noncompliant patient, reucrrence after medical therapy, children, pregnant women not controlled with PTU, or concomitant suspicious thyroid nodule

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78
Q
  • Women, age > 50 years, usually nontoxic 1st
  • Symptoms: tachycardia, weight loss, insomnia, airway compromise, symptoms can be precipitated by contrast dyes
  • Caused by hyperplasia secondary to chronic low-grade TSH stimulation
A

Toxic multinodular goiter

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79
Q

Tx: toxic multinodular goiter

A

Most consider surgery (subtotal or total thyroidectomy) the preferred initial treatment for toxic multi nodular goiter, but a trial of i-131 should be considered, especially in the elderly and frail.
- If compression of a suspicious nodule is present, need to go with surgery

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80
Q
  • Women, younger, usually > 3cm to be symptomatic, function autonomously.
A

Single toxic nodule

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81
Q

Dx and Tx: Single toxic nodule

A

Dx: thyroid scan (hot nodule) - 20% of hot nodules eventually cause symptoms
Tx: thioamides and 131-i (95% effective). lobectomy if medical treatment ineffective

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82
Q

Rare causes of hyperthyroidism

A

Trophoblastic tumors, TSH-secreting pituitary tumors.

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83
Q

MCC hypothyroidism in adults

A

Hashimoto’s disease

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84
Q
  • Enlarged gland, painless, chronic thyroiditis
  • Women, history of childhood XRT
  • Can cause thyrotoxicosis in the acute early stage
A

Hashimoto’s disease

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85
Q

What causes Hashimotos’ disease?

A
  • Caused by both humeral and cell-mediated autoimmune disease (microsomal and thyroglobulin antibodies)
  • Goiter secondary to lack of organification of trapped iodide inside gland
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86
Q

What does pathology show for Hashimoto’s thyroiditis?

A

Pathology shows a lymphocytic infiltrate

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87
Q

Tx: Hashimotos’ thryoidits

A

Thyroxine (first line), partial thyroidectomy if continues to grow despite thyroxine, if nodules appear, or if compression symptoms occur

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88
Q
  • Usually secondary to contiguous spread
  • Bacterial URI usual precursors (staph/strep)
  • Normal thyroid function tests, fever, dysphagia, tenderness
A

Bacterial thyroiditis (rare)

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89
Q

Tx: bacterial thyroiditis

A

Antibiotics

  • May need lobectomy to r/o CA in pts w/ unilateral swelling and tenderness.
  • May need total thyroidectomy for persistent inflammation
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90
Q
  • Can be a/w hyperthyroidism initially
  • Viral URI precursor, tender thyroid, sore throat, mass, weakness, fatigue, women.
  • Elevated ESR.
A

De Quervain’s thyroiditis

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91
Q

Tx: De Quervain’s thyroiditis

A

Steroids and ASA

  • May need lobectomy to r/o CA in pts w/ unilateral swelling and tenderness.
  • May need total thyroidectomy for persistent inflammation
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92
Q
  • Woody, fibrous component that can involve adjacent strap muscles and carotid sheath
  • Can resemble thyroid CA or lymphoma (need biopsy)
  • Disease frequently results in hypothyroidism and compression symptoms
A

Riedel’s fibrous struma (rare)

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93
Q

What is Riedel’s fibrous struma associated with?

A

Sclerosing cholangitis.
Fibrotic disease.
Methysergide Tx.
Retroperitoneal fibrosis.

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94
Q

Tx: Riedel’s fibrous struma

A

Steroids and thyroxine

  • May need isthmectomy or tracheostomy for airway symptoms
  • If resection needed, watch for RLNs.
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95
Q

Most common endocrine malignancy in the US

A

Thyroid cancer

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96
Q

% Chance of malignancy with follicular cells on FNA

A

5-10% chance of malignancy

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97
Q

DDx follicular cells on FNA

A

Follicular cell adenoma vs follicular hyperplasia vs follicular cell CA

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98
Q

Thyroid CA: characteristics with increased chance of malignancy

A

Solid, solitary, cold, slow growing, hard, male, age > 50, previous neck XRT, MEN 2a or 2b

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99
Q

DDx: sudden growth of thyroid cancer

A

Could be hemorrhage into previously undetected nodule or malignancy

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100
Q

Patients can present with voice changes or dysphagia

A

Think about thyroid cancer

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101
Q
  • Colloid, embryonal, fetal -> no increased cancer risk.

- Tx: still need lobectomy to prove it is an adenoma

A

Follicular adenoma

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102
Q

MC (85%) thyroid cancer

A

Papillary thyroid carcinoma

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103
Q
  • Least aggressive, slow growing, has the best prognosis; women, children
  • Older age (>40-50yrs) predicts a worst prognosis.
  • Children are more likely to be node positive (80%) than are adults (20%)
A

Papillary thyroid carcinoma

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104
Q

Risk factors of papillary thyroid carcinoma

A

Childhood XRT (very increased risk) -> MC tumor following neck XRT

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105
Q

How do you ascertain prognosis of papillary thyroid carcinoma?

A

Lymphatic spread 1st but is not prognostic -> prognosis based on local invasion

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106
Q

Papillary thyroid CA: mets?

A

Rare - lung

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107
Q

Path: papillary thyroid CA

A

psammoma bodies (calcium) and Orphan Annie nuclei

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108
Q

Tx: papillary thyroid CA

A
  • Minimal/incidental ( 1cm
  • Clinically + cervical LN: need ipsilateral MRND
  • Extrathyroidal tissue involvement: need ipsilateral MRND
  • Mets, residual local disease, +LN, capsular invasion -> 131-i (4-6wks after surgery
  • XRT only for unresectable disease not responsive to 131-i
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109
Q

When would you do total thyroidectomy for papillary thyroid carcinoma?

A

Bilateral lesions, multicentricity, history of XRT, positive margins, tumors > 1cm

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110
Q

Survival rate papillary thyroid CA

A

95% 5-year survival rate; death secondary to local disease

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111
Q

Dx: enlarged lateral neck lymph node that shows normal-appearing thyroid tissue.
Tx: ?

A

Dx: Papillary thyroid CA with lymphatic spread (lateral aberrant thyroid tissue)
Tx: total thyroidectomy and MRND; 131-i (4-6weeks after surgery)

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112
Q
  • Hematogenous spread (bone most common) -> 50% have metastatic disease at the time of presentation.
  • More aggressive than thyroid papillary cell CA; older adults (50-60s), women
A

Follicular thyroid carcinoma

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113
Q

What if FNA shows just follicular cells?

A

10% have chance of malignancy. Need lobectomy.

114
Q

Tx: follicular thyroid carcinoma

A

Lobectomy -> if path shows adenoma or follicular cell hyperplasia, nothing else needed.

  • Follicular CA: total thyroid for lesions > 1 or extra thyroid disease
  • Clinically positive cervical nodes: ipsilateral MRND.
  • Extrathyroid involvement: ipsilateral MRND.
  • Lesions > 1cm or extrathyroid: 131-i (4-6 wks after surgery)
115
Q

Survival rate follicular thyroid carcinoma

A

70% 5-year survival rate; prognosis based on stage

116
Q
  • Can be a/w MEN 2a, 2b (diarrhea)
  • Usually the 1st manifestation of MEN 2a / 2b (diarrhea)
  • Tumor arises from parafollicular C cells (which secrete calcitonin)
  • C-cell hyperplasia considered premalignant
A

Medullary thyroid carcinoma

117
Q

Path: medullary thyroid carcinoma

A

Shows amyloid deposition

118
Q

What do you need to screen for with medullary thyroid carcinoma?

A

Hyperparathyroidism and pheochromocytoma.

119
Q

Metastatic risk for medullary thyroid carcinoma

A
  • Lymphatic spread: most have involved nodes at time of diagnosis
  • Early mets to lung, liver, and bone.
120
Q

MC site of mets in follicular thyroid carcinoma

A

Bone

121
Q

Treatment: medullary thyroid carcinoma

A

Tx: total thyroid with central neck node dissection.

  • MRND: if +nodes (bilateral MRND if both lobes have tumor) or if extra thyroidal disease present.
  • XRT may be useful for unresectable local and distant metastatic disease.
122
Q

When would you consider prophylactic thyroidectomy and central node dissection?

A

In medullary thyroid carcinoma.

- in MEN 2a (at age 6 years) or 2b (at 2 years)

123
Q

What prevents attempt at cure of medullary thyroid carcinoma?

A

Liver and bone metastases

124
Q

Monitor for recurrence of medullary thyroid carcinoma

A

Calcitonin levels

125
Q

Survival rate of medullary thyroid carcinoma

A

50% 5-year survival rate, prognosis based on presence of regional and distant metastasis.

126
Q
  • Most are benign, presents in older patients.
  • Mets go to bone and lung if malignant.
  • Tx?
A

Hurthle cell carcinoma.

Tx: total thyroidectomy, MRND for clinically positive nodes

127
Q
  • Elderly patients with long-standing goiters
  • Most aggressive thyroid CA
  • Rapidly lethal, usually beyond surgical management at diagnosis.
A

Anaplastic thyroid cancer

128
Q

Tx: Anaplastic thyroid carcinoma

A

Total thyroidectomy for the rare lesion that can be resected.
- Can perform palliative thyroidectomy for compressive symptoms or give palliative chemo-XRT

129
Q

Survival rate anaplastic thyroid cancer

A

Rapidly lethal: 0% at 5-year

130
Q

What is XRT effective for?

A

Papillary, follicular, medullary, and Hurthle cell thyroid CA

131
Q

What is 131-i effective for?

A

Papillary and follicular thyroid CA only

132
Q

How do you use 131-i?

A
  • Can cure bone and lung mets
  • Give 4-6 wks after surgery when TSH levels are highest.
  • Do not give thyroid replacement until after treatment with 131-i -> would suppress TSH and uptake of 131-i.
133
Q

Indications for 131-i

A

Used only for papillary and follicular thyroid CA

  • Recurrent CA
  • Primary inoperable tumors due to local invasion
  • Tumors that are > 1cm or have extra thyroidal disease (extra-capsular invasion, nodal spread, or mets)
134
Q

Why does total thyroidectomy need to be performed for patients with papillary or follicular cell CA and mets for i-131 treatment?

A

Need to perform total thyroidectomy to facilitate uptake of i-131 to the metastatic lesions (otherwise all gets absorbed by the thyroid gland)

135
Q

Side effects: i-131 (rare)

A

Sialoadenitis, GI symptoms, infertility, bone marrow suppression, parathyroid dysfunction, leukemia

136
Q

Can help suppress TSH an slow metastatic disease; administered only after i-131 therapy has finished

A

Thyroxine

137
Q

Define the arterial blood supply to the thyroid.

A
  1. Superior thyroid artery (first branch off external carotid)
  2. Inferior thyroid artery (branch of thyrocervical trunk) (IMA artery rare)
138
Q

What is the venous drainage of the thyroid?

A
  1. Superior thyroid vein
  2. Middle thyroid vein
  3. Inferior thyroid vein
139
Q

Name the thyroid lobe appendage coursing toward the hyoid bone from around the thyroid isthmus.

A

Pyramidal lobe.

140
Q

What percentage of patients have a pyramidal lobe?

A

~50%.

141
Q

What veins do your first see after opening the platysma muscle when performing a thyroidectomy?

A

Anterior jugular veins.

142
Q

Name the lymph node group around the pyramidal thyroid lobe.

A

Delphian lymph node group.

143
Q

What is the thyroid isthmus?

A

Midline tissue border between the left and right thyroid lobes.

144
Q

Which ligament connects the thyroid to the trachea?

A

Ligament of Berry

145
Q

What is the IMA artery?

A

Small inferior artery to the thyroid from the aorta or innominate artery

146
Q

What percentage of patients have a IMA artery?

A

~3%

147
Q

Name the most posterior extension of the lateral thyroid lobes.

A

Tubercle of Zuckerkandl

148
Q

Which paired nerves must be carefully identified during a thyroidectomy?

A

Recurrent laryngeal nerves, which are found in the tracheoesophageal grooves and dive behind the cricothyroid muscle; damage to these nerves paralyzes laryngeal abductors and causes hoarseness if unilateral and airway obstruction if bilateral.

149
Q

What other nerve is at risk during a thyroidectomy and what are the symptoms?

A

Superior laryngeal nerve; if damaged, patient will have a deeper and quicker voice (unable to hit high pitches)

150
Q

What is TRH?

A

Thyrotropin-releasing hormone: released from hypothalamus, causes release of TSH

151
Q

What is TSH?

A

Thyroid-stimulating hormone: release by the anterior pituitary; causes release of thyroid hormone from the thyroid

152
Q

What are the thyroid hormones?

A

T3 and T4

153
Q

What is the most active form of thyroid hormone?

A

T3

154
Q

What is a negative feedback loop?

A

T3 and T4 feed back negatively on the anterior pituitary (causing decreased release of TSH in response to TRH)

155
Q

What is the most common site of conversion of T4 to T3?

A

Peripheral (eg, liver)

156
Q

What is Synthroid (levothyroxine): T3 or T4?

A

T4

157
Q

What is the half-life of Synthroid (levothyroxine)?

A

7 days

158
Q

What do parafollicular cells secrete?

A

Calcitonin

159
Q

What percentage of people have a thyroid nodule?

A

~ 5%

160
Q

What is the differential diagnosis of a thyroid nodule?

A 
Multinodular goiter
Adenoma
Hyperfunctioning adenoma
Cysts
Thyroiditis
Carcinoma / lymphoma
Parathyroid carcinoma
161
Q

Name three types of non thyroidal neck masses.

A
  1. Inflammatory lesions (eg, absecess, lymphadenitis)
  2. Congenital lesions (ie thyroglossal duct (midline), branchial cleft cyst (lateral)
  3. Malignant lesions: lymphoma, mets, SCCa
162
Q

What studies can be used to evaluate a thyroid nodule?

A

US - solid or cystic nodule
FNA
131-i: hot or cold nodule

163
Q

What is the diagnostic test of choice for thyroid nodule?

A

FNA

164
Q

What is the percentage of false negative results on FNA for thyroid nodule?

A

~ 5%

165
Q

What is meant by a hot vs cold nodule?

A

Nodule uptake of IV 131-i or 69-mT

  • Hot: increased 131-i uptake -> functioning / hyper functioning nodule
  • Cold: decreased 131-i uptake -> nonfunctioning nodule
166
Q

What are the indications for a 123-i scintiscan?

A
  1. Nodule with multiple “non diagnostic” FNAs with low TSH

2. Nodule with thyrotoxicosis and low TSH

167
Q

What is the role of thyroid suppression of a thyroid nodule?

A

Diagnostic and therapeutic; administration of thyroid hormone suppresses TSH secretion and up to half of the benign thyroid nodules will disappear

168
Q

History -> suggest thyroid CA

A
  1. Neck radiation
  2. Family history (thyroid cancer, MEN2)
  3. Young age (especially children)
  4. Male > female
169
Q

Signs -> suggest thyroid CA

A
  1. Single nodule
  2. Cold nodule
  3. Increased calcitonin levels
  4. Lymphadenopathy
  5. Hard, immobile nodule
170
Q

Symptoms -> suggest thyroid CA

A
  1. Voice change (vocal cord paralysis)
  2. Dysphagia
  3. Discomfort (in neck)
  4. Rapid enlargement
171
Q

What is the MCC thyroid enlargement?

A

Multinodular goiter

172
Q

What are indications for surgery with multi nodular goiter?

A

Cosmetic deformity, compressive symptoms, cannot r/o cancer

173
Q

What is Plummer’s disease?

A

Toxic multinodular goiter

174
Q

What % of cold thyroid nodules are malignant?

A

~ 25% in adults

175
Q

What % of multi nodular masses are malignant?

A

~ 1%

176
Q

What is the treatment of a patient with a h/o radiation exposure, thyroid nodule, and negative FNA?

A

Most experts would remove the nodule surgically (Because of the high risk of radiation)

177
Q

What should be done with thyroid cyst aspirate?

A

Send to cytopathology

178
Q

Name the FIVE main types of thyroid carcinoma and their relative percentages.

A
  1. Papillary: 80%
  2. Follicular: 10%
  3. Medullary: 5%
  4. Hurthle cell: 4%
  5. Anaplastic: 1-2%
179
Q

What are the s/s thyroid CA?

A

Mass / nodule, lymphadenopathy, most are euthyroid

180
Q

What comprises the thyroid CA work up?

A

FNA, thyroid U/S, TSH, calcium level, CXR, +/- scintiscan 123-i

181
Q

What oncogenes are associated with thyroid cancers?

A

Ras gene family and RET porto-oncogene.

182
Q

What is papillary carcinoma’s claim to fame?

A

MC thyroid cancer - 80% of all thyroid cancers

183
Q

Environmental risk: papillary CA

A

radiation exposure

184
Q

Average age: papillary CA

A

30-40 years

185
Q

Sex distribution: papillary CA

A

Female > male - 2:1

186
Q

Associated histologic findings: papillary CA

A

Psammoma bodies

187
Q

Describe the route and spread - papillary CA

A

Most spread via lymphatics (cervical adenopathy); occurs slowly

188
Q

papillary CA: i-131 uptake

A

Good uptake

189
Q

What is the 10-year survival rate of papillary CA?

A

~ 95%

190
Q

What is the treatment for

A
  1. Thyroid lobectomy and isthmectomy
  2. Near-total thyroidectomy
  3. Total thyroidectomy
191
Q

What is the treatment for papillary CA > 1.5 cm, bilateral, + cervical node mets, OR a h/o radiation exposure?

A

Total thyroidectomy

192
Q

Does positive cervical nodes affect prognosis of papillary CA?

A

No!

193
Q

What is the treatment for lateral palpable cervical lymph nodes in papillary CA?

A

Modified neck dissection (ipsilateral)

194
Q

What is the treatment for central cervical lymph nodes of papillary CA?

A

Central neck dissection

195
Q

What is a “lateral aberrant thyroid” in papillary cancer?

A

Misnomer - it is metastatic papillary carcinoma to a LN

196
Q

What post op med should be administered in papillary CA?

A

Thyroid hormone replacement, to suppress TSH

197
Q

What is the postoperative treatment option for papillary carcinoma?

A

Post op 131-i scan can locate residual tumor and distant mets that can be treated with ablative doses of 131-i.

198
Q

What is the MC site of distant mets in papillary CA?

A

Pulmonary (lungs)

199
Q

What are the “P’s” of papillary CA?

A

Popular. Psammoma bodies. Palpable lymph nodes. Positive 131-i uptake. Positive prognosis. Postop 131-i scan. Pulmonary mets.

200
Q

What percentage of thyroid cancers is follicular CA?

A

~ 10%

201
Q

Describe the nodule consistency of follicular CA?

A

Rubbery, encapsulated

202
Q

What is the route of spread of follicular CA??

A

Hematogenous, more aggressive than papillary adenocarcinoma

203
Q

What is the male:female ratio of follicular CA?

A

1:3

204
Q

131-i uptake follicular CA?

A

Good uptake

205
Q

What is the overall 10-year survival rate follicular CA?

A

~ 55%

206
Q

Can the diagnosis of follicular CA be made by FNA?

A

No; tissue structure is needed for the diagnosis of cancer.

207
Q

What histologic findings describe malignancy in follicular CA?

A

Capsular or blood vessel incasion

208
Q

What is the MC site of distant mets of follicular CA?

A

Bone

209
Q

What is the treatment of follicular CA?

A

Total thyroidectomy

210
Q

What is the post op treatment option of follicular CA?

A

Post op 131-i scan for diagnosis / treatment

211
Q

What are the four F’s of follicular cancer?

A

Far-away mets (spreads hematogenously)
Female (3:1 ratio)
FNA
Favorable prognosis

212
Q

What is hurthle cell thyroid Ca?

A

Thyroid cancer of hurthle cells

213
Q

What percentage of thyroid cancers is hurthle cell thyroid Ca?

A

~ 5%

214
Q

What is the cell of origin of Hurthle cell?

A

Follicular cells

215
Q

131-i uptake in hurthle cell ca?

A

No uptake

216
Q

How is the diagnosis of hurthle cell ca made?

A

FNA can identify cells, but malignancy can be determined only by tissue histology (like follicular cancer)

217
Q

What is the route of metastasis of hurthle cell ca?

A

Lymphatic > hematogenous

218
Q

What is the treatment of hurthle cell ca?

A

Total thyroidectomy

219
Q

What is the 10-year survival rate of hurthle cell ca?

A

80%

220
Q

What percentage of all thyroid cancers does medullary carcinoma comprise?

A

~ 5%

221
Q

With what other conditions is medullary carcinoma associated?

A

MEN type 2; autosomal-dominant genetic transmission

222
Q

Histology of medullary carcinoma?

A

Amyloid

223
Q

What is the tumor marker of medullary carcinoma?

A

Calcitonin

224
Q

What is the appropriate stimulation test for medullary carcinoma?

A

Pentagastrin (causes an increase in calcitonin)

225
Q

Describe the route of spread of medullary carcinoma

A

Lymphatic and hematogenous distant mets

226
Q

How is the diagnosis of medullary carcinoma made?

A

FNA

227
Q

131-i uptake medullary carcinoma

A

Poor uptake

228
Q

What is the associated genetic mutation of medullary carcinoma

A

RET proto-oncogene

229
Q

What is the female/male ratio of medullary carcinoma?

A

Female > male; 1.5:1

230
Q

What is the 10-year survival rate of medullary carcinoma?

A

80% without LN involvement. 45% with LN spread.

231
Q

What should all patients with medullary thyroid cancer also be screened for?

A

MEN2: pheochromocytoma, hyperparathyroidism

232
Q

If medullary carcinoma and pheochromocytoma are found, which one is operated on first?

A

Pheochromocytoma

233
Q

What is the treatment of medullary carcinoma?

A

Total thyroidectomy and median lymph node dissection. Modified neck dissection, if lateral cervical nodes are positive.

234
Q

What are the M’s of medullary carcinoma?

A

MEN II
Amyloid
Median lymph node dissection
Modified neck dissection if lateral nodes are positive

235
Q

What is anaplastic carcinoma is also known as?

A

Undifferentiated carcinoma

236
Q

What is anaplastic carcinoma?

A

Undifferentiated cancer arising in ~ 75% of previously differentiated thyroid cancers (MC’ly, follicular carcinoma)

237
Q

What percentage of all thyroid cancers does anaplastic carcinoma comprise?

A

~ 2%

238
Q

What is the gender preference of anaplastic carcinoma?

A

Women > Men

239
Q

What are the associated histologic findings of anaplastic carcinoma?

A

Giant cells, spindle cells

240
Q

131-i uptake of anaplastic carcinoma?

A

Very poor uptake

241
Q

How is the diagnosis made of anaplastic carcinoma?

A

FNA (large tumor)

242
Q

What is the major differential diagnosis of anaplastic carcinoma?

A

Thyroid lymphoma (much better prognosis)

243
Q

What is the treatment of the following disorders: small tumors of anaplastic carcinoma?

A

Total thyroidectomy + XRT / chemotherapy

244
Q

What is the treatment of airway compromise of anaplastic carcinoma?

A

Debulking surgery and tracheostomy, XRT/chemotherapy

245
Q

What is the prognosis of anaplastic carcinoma?

A

Dismal, because most patients are at stage IV at presentation (3% alive at 5 years)

246
Q

What lab value must be followed postoperatively after a thyroidectomy?

A

Calcium decreased secondary to parathyroid damage; during lobectomy, the parathyroids must be spared and their blood supply protected; if blood supply is compromised intraoperatively, they can be autographed into the SCM or forearm

247
Q

What is the differential diagnosis of postoperative dyspnea after a thyroidectomy?

A
  • Neck hematoma (remove sutures and clot at the bedside).

- Bilateral recurrent laryngeal nerve damage

248
Q

What is a “lateral aberrant rest” of the thyroid?

A

Misnomer: it is papillary cancer of a lymph node from metastasis

249
Q

What is the MCC hyperthyroidism?

A

Graves’ disease

250
Q

What is Graves’ disease?

A

Diffuse goiter with hyperthyroidism, exophthalmos, and pretibial myxedema

251
Q

What is the etiology of Graves’?

A

Caused by circulating antibodies that stimulate TSH receptor on follicular cells of the thyroid and cause deregulated production of thyroid hormones (i.e., hyperthyroidism)

252
Q

What is the female: male ratio of graves’ disease?

A

6:1

253
Q

What specific physical finding is a/w Graves’?

A

Exophthalmos

254
Q

How is the diagnosis made of Graves’?

A

Increased T3, T4, and anti-TSH receptor antibodies, decreasedTSH, global uptake of 131-i radionuclide

255
Q

Name treatment option modalities for Graves’ disease.

A
  1. Medical blockade: iodide, propranolol, PTU, methimazole, Lugol’s solution
  2. Radioiodide ablation: most popular therapy
  3. Surgical resection: bilateral subtotal thyroidectomy
256
Q

What are the possible indications for surgical resection of Graves’ disease?

A

Suspicious nodule; if patient is noncompliant or refractory to medicines, pregnant, a child, or if patient refuses radio iodide therapy.

257
Q

What is the major complication of radio iodide or surgery for Graves’ disease?

A

Hypothyroidism

258
Q

What does PTU stand for?

A

Propylthiouracil

259
Q

How does PTU work?

A
  1. Inhibits incorporation of iodine into T4/T3 (by blocking peroxidase oxidation of iodine to iodine)
  2. Inhibits peripheral conversion of T4 to T3
260
Q

How does methimazole work?

A

Inhibits incorporation of iodine into T4/T3 only (by blocking peroxidase oxidation of iodine to iodine)

261
Q

What is toxic multi nodular goiter?

A

Plummer’s disease

262
Q

What is toxic multi nodular goiter?

A

Multiple thyroid nodules with one or more nodules producing thyroid hormone, resulting in hyper functioning thyroid (hyperthyroidism or a “toxic” thyroid state)

263
Q

What medication may bring on hyperthyrdoisim with a multi nodular goiter?

A

Amiodarone (or any iodine-containing medication / contrast)

264
Q

How is the hyper functioning thyroid nodule localized?

A

131-i radionuclide scan

265
Q

What is the treatment of toxic multi nodular goiter?

A

Surgically remove hyper functioning nodules with lobectomy or near total thyroidectomy

266
Q

What is Pemberton’s sign?

A

Large goiter causes plethora of head with raising of both arms.

267
Q

What are the features of acute thyroiditis?

A

Painful, swollen thyroid, fever, overlying skin erythema, dysphagia

268
Q

What is the cause of acute thyroiditis?

A

Bacteria (usually Streptococcus or Staphylococcus), usually caused by a thyroglossal fistula or anatomic variant

269
Q

What is the treatment of acute thyroiditis?

A

Antibiotics, drainage of abscess, needle aspiration for culture, most patients need definitive surgery later to remove the fistula.

270
Q

What are the features of subacute thyroiditis?

A

Glandular swelling, tenderness, often follows URI, elevated ESR

271
Q

What is the cause of subacute thyroiditis?

A

Viral infection

272
Q

What is De Quervain’s thyroiditis?

A

Another name for subacute thyroiditis

273
Q

How can the difference between the etiologies of acute and subacute thyroiditis be remembered?

A

A before S, B before V. (Acute before Subacute, Bacterial before Viral. (Acute: bacterial, Subacute: viral)

274
Q

What are the common causative bacteria in acute suppurative thyroiditis?

A

Streptococcus or Staphylococcus

275
Q

What are the two types of chronic thyroiditis?

A
  1. Hashimoto’s thyroiditis

2. Reidel’s thyroidits

276
Q

What are the features of Hashimoto’s (chronic) thyroiditis?

A

Fine and rubbery gland, 95% in women, lymphocyte invasion.

277
Q

What is the claim to fame of Hashimoto’s disease?

A

MCC hypothyroidism in the US

278
Q

What is the etiology of Hashimoto’s disease?

A

Autoimmune

279
Q

What lab tests should be performed to diagnose Hashimoto’s disease?

A

Antithyroglublin and microsomal antibodies

280
Q

What is the medical treatment for Hashimoto’s thyroiditis?

A

Thyroid hormone replacement if hypothyroid (surgery is reserved for compressive symptoms and/or if cancer needs to be ruled out)

281
Q

What is Riedel’s thyroiditis?

A

Benign inflammatory thyroid enlargement with fibrosis of the thyroid. Patients present with painless, large thyroid. Fibrosis may involve surrounding tissues.

282
Q

What is the treatment for Riedel’s thyroiditis?

A

Surgical tracheal decompression, thyroid hormone replacement as needed - possibly steroids / tamoxifen if refractory.

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