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Endocriknowlogy > Thyroid: Thyroid Nodular Disease & Thyroid Cancer > Flashcards

Thyroid: Thyroid Nodular Disease & Thyroid Cancer Flashcards

1
Q

Diffuse nontoxic goiter / simple goiter / colloid goiter is termed “endemic goiter” when it affects >__% of the population.

A

> 5%

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2
Q

Food that are high in goitrogens

A

Cassava root (contains thiocyanate)

Vegetables of the Cruciferae family (i.e. Brussels sprouts, cabbage, cauliflower)

Milk (from regions where goitrogens are present in the grass)

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3
Q

Total thyroid volume on ultrasound that is considered abnormal

A

> 30 mL

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4
Q

What is Pemberton’s sign

A

Facial and neck congestion due to jugular venous obstruction when the arms are raised above the head, a maneuver that draws the thyroid into the thoracic inlet; suggests that the goiter has increased pressure in the thoracic inlet

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5
Q

Usual TFT in simple goiter

A

Low total T4, normal T3 and TSH (reflecting enhanced T4 to T3 conversion)

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6
Q

Treatment of diffuse nontoxic (simple) goiter

A

Iodine replacement

Surgery if with tracheal compression or obstruction of the thoracic inlet

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7
Q

Target TSH level after thyroidectomy for simple goiter

A

Keep TSH level at lower end of reference interval (to prevent regrowth of the goiter)

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8
Q

TRUE OR FALSE: Most nodules within a mutinodular goiter are polyclonal in origin.

A

TRUE (suggesting a hyperplastic response to locally produced growth factors and cytokines)

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9
Q

Usual cause of sudden pain in a multinodular goiter

A

Hemorrhage into a nodule (but should raise the possibility of invasive malignancy)

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10
Q

In multinodular goiter, airway compression must usually exceed __% of the tracheal diameter before there is significant airway compromise.

A

70%

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11
Q

Grayscale sonographic features associated with thyroid cancer (6)

A

1) Hypoechoic compared with surrounding thyroid
2) Marked hypoechogenicity
3) Microcalcifications
4) Irregular, microlobulated margins
5) Solid consistency
6) Taller than wide shape on transverse view

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12
Q

Sonographic feature that is most sensitive for thyroid cancer

A

Solid consistency (86%)

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13
Q

Sonographic feature that is most specific for thyroid cancer

A

Marked hypoechogenicity (94%)

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14
Q

Dosage of 131I in the treatment of multinodular goiter

A

3.7 MBq (0.1 mCi) per gram of tissue, corrected for uptake (typical dose 370-1070 MBq (10-29 mCi)

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15
Q

Usual TFT in toxic multinodular goiter

A

T3 is often elevated to a greater degree than T4

TSH is low

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16
Q

Treatment of toxic multinodular goiter

A

Radioiodine - treatment of choice

Antithyroid drugs - in elderly or ill patients with limited lifespan

Surgery - definitive treatment

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17
Q

Most common mutation in patients with hyperfunctioning solitary nodule

A

Activating mutations of the thyroid-stimulating hormone receptor (TSH-R) mainly in transmembrane 5 and intracellular loop 3

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18
Q

TRUE OR FALSE: In hyperfunctioning solitary nodule, thyrotoxicosis is usually mild and is generally only detected when a nodule is >3cm.

A

TRUE

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19
Q

Treatment of hyperfunctioning solitary nodule

A

Radioiodine ablation - treatment of choice

Surgical resection - limited to lobectomy

Medical therapy - not an optimal long-term treatment

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20
Q

Description of follicular architecture in benign thyroid lesions

A

Hyperplastic - combination of macro- and microfollicular architecture

Neoplastic - more monotonous microfollicular pattern

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21
Q

What is a Hurthle cell adenoma

A

Term used to denote an adenoma that is composed of oncocytic follicular cells arranged in a follicular pattern

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22
Q

The definition of “spongiform” requires the presence of microcystic areas comprising >__% of the nodule volume.

A

> 50%

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23
Q

When can iodine and levothyroxine be given in cases of benign thyroid nodules

A

In cases of relative iodine deficiency (must maintain TSH at or just below the lower limit of normal, and discontinue treatment if the nodule has not decreased in size after 6-12 months)

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24
Q

What is the most common malignancy of the endocrine system?

A

Thyroid carcinoma

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25
Q

TRUE OR FALSE: Thyroid cancer prognosis is worse in older persons (>65 years) and in males.

A

TRUE

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26
Q

Risk factors for thyroid carcinoma in patients with thyroid nodule from history and physical examination

A

History of head and neck irradiation before the age of 18, including mantle radiation for Hodgkin’s disease, and brain radiation for childhood leukemia or other cranial malignancies

Exposure to ionizing radiation from fallout in childhood or adolescence

Age <20 or >65 years

Rapidly enlarging neck mass

Male gender

Family history of papillary thyroid cancer in 2 ore more first degree relatives, MEN 2, or other genetic syndromes associated with thyroid malignancy (e.g., Cowden’s syndrome, familial polyposis, Carney complex, phosphatase and tensin homolog (PTEN) hamartoma tumor)

Vocal cord paralysis, hoarse voice

Nodule fixed to adjacent structures

Lateral cervical lymphadenopathy

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27
Q

Staging of PTC and FTC: Cut-off age for staging (Harrison’s)

A

45 years

If patient is <45 years, he/she can only be either Stage I or Stage II, depending on the presence of metastasis

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28
Q

Which classification of thyroid cancer is always at Stage IV?

A

Anaplastic thyroid cancer

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29
Q

Cancer staging: T

A

T1a <=1cm
T1b >1cm

T2 >2cm but <=4cm

T3 >4cm or any tumor with extension into perithyroidal soft tissue or sternothyroid muscle

T4a invasion into subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve
T4b invasion into prevertebral fascia or encasement of carotid artery or mediastinal vessels

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30
Q

Cancer staging: N

A

N0 - absence

N1a - level IV central compartment

N1b - level II-V lateral compartment, upper mediastinal or retro/parapharyngeal

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31
Q

Papillary or Follicular Thyroid Cancer Staging in >45 years old

A

Stage I - T1N0M0

Stage II - T2N0M0

Stage III - T3N0M0
- T1-T3, N1a, M0

Stage IVA - T4a, any N, M0
- T1-T3, N1b, M0
Stage IVB - T4b, any N, M0
Stage IVC - Any T, any N, M1

32
Q

New age cutoff based on the AJCC guidelines released in 2018

A

55 years

33
Q

TRUE OR FALSE: Multinodular goiters are polyclonal while thyroid cancers are monoclonal in origin.

A

TRUE

34
Q

Activation of the _____________ signaling pathway is seen in up to 70% of PTCs.

A

RET-RAS-BRAF signaling pathway

35
Q

Activation of this cascade is believed to be critical for tumor development in thyroid cancer, independent of the step that initiates the cascade.

A

Mitogen-activated protein kinase (MAPK) cascade

36
Q

Most common genetic alteration in PTC

A

BRAF V600E

37
Q

Most common RAS mutations in thyroid neoplasms

A

NRAS > HRAS > KRAS

38
Q

MTC, when associated with MEN type 2, harbors an inherited mutation in the ___ gene.

A

RET (point mutations that induce constitutive activity of the tyrosine kinase)

39
Q

Most common type of thyroid cancer

A

PTC (80-85% of well-differentiated thyroid malignancies)

40
Q

Characteristic cytologic features of PTC

A

Large, clear nuclei with powdery chromatic (“orphan Annie eye” appearance) with nuclear grooves and prominent nucleoli

41
Q

PTC has a propensity to spread via

A

Lymphatic system

42
Q

TRUE OR FALSE: Micrometastases, defined as <2 mm of cancer in a lymph node, do not affect prognosis.

A

TRUE

43
Q

Gross metastatic involvement of multiple 2-3 cm lymph nodes indicates a 25-30% chance of recurrence.

A

TRUE

44
Q

Which type of thyroid cancer is more common in iodine-deficient regions?

A

FTC

45
Q

TRUE OR FALSE: The nuclear features of benign and malignant follicular adenomas and carcinomas are different and, hence, FNA can be used to distinguish between the two.

A

FALSE. The nuclear feature of the two are not different. Histology is required. Follicular carcinoma is diagnosed by the presence of capsular and/or vascular invasion.

46
Q

FTC has a propensity to spread via

A

Hematogenous route

47
Q

Poor prognostic features of FTC

A

Distant metastases, age >50 years, primary tumor size >4 cm, Hurthle cell histology, and the presence of marked vascular invasion

48
Q

Treatment of choice for well-differentiated thyroid cancers >1cm

A

Surgical excision

49
Q

Medication that is a mainstay of thyroid cancer treatment

A

Levothyroxine (because most tumors are still TSH-responsive, TSH must be suppressed with LT4)

50
Q

Target TSH in patients with thyroid cancer with high risk of recurrence of with known metastatic disease

A

<0.1 mIU/L

51
Q

Indications for radioiodine treatment in thyroid cancer

A

Large tumors
More aggressive variants of papillary cancer
Tumor vascular invasion
Extrathyroidal invasion
Presence of large-volume lymph node metastases

(Radioiodine reduces recurrence and may increase survival for older patients)

52
Q

Prerequisite before thyroid ablation

A

Radioablation is much more effective when there is minimal remaining normal thyroid tissue, hence it is administered after iodine depletion

  • Low iodine diet for 1-2 weeks
  • Elevated serum TSH, ideally >25 mIU/L (give liothyronine then withdraw for 2 weeks, or give recombinant TSH as 2 daily consecutive injections)
53
Q

Surveillance testing after RAI for thyroid cancer

A

Serum thyroglobulin

Neck ultrasound after 6 months

Whole body scan if with known iodine-avid metastases or with elevated serum thyroglobulin and negative ultrasound, chest CT, neck cross-sectional imaging, and PET CT

54
Q

Kinase inhibitor that is currently being studied as treatment in progressive metastatic thyroid cancer

A

Sorafenib

55
Q

Type of cancer that is poorly differentiated and aggressive, wherein most patients die within 6 months of diagnosis

A

Anaplastic thyroid cancer

56
Q

Thyroid lymphoma often arises in the background of what kind of thyroiditis?

A

Hashimoto’s thyroiditis

57
Q

Most common type of thyroid lymphoma

A

Diffuse large-cell lymphoma

58
Q

Treatment of choice in thyroid lymphoma

A

External radiation (highly sensitive; surgical resection should be avoided as initial therapy because it may spread disease)

59
Q

TRUE OR FALSE: MTC is more aggressive in MEN 2B than in MEN 2A, and familial MTC is more aggressive than sporadic MTC.

A

TRUE

60
Q

Marker of residual or recurrent disease in MTC

A

Serum calcitonin

61
Q

All patients with MTC should be tested for ___ mutations.

A

RET mutations

62
Q

Treatment of choice in MTC

A

Surgery

63
Q

What should be ruled out prior to surgery of MTC?

A

Pheochromocytoma

64
Q

TRUE OR FALSE: Thyroid nodules are more common in iodine-sufficient areas, in women, and in young individuals.

A

FALSE. Nodules are more common in iodine-deficient areas, in women, and with aging.

65
Q

Evaluation of a thyroid nodule: First step

A

Check TSH level

66
Q

Evaluation of a thyroid nodule: Next step if TSH is suppressed

A

Radionuclide scan

67
Q

Evaluation of a thyroid nodule: Next step if TSH is showed a “hot” nodule

A

Evaluate and treat for hyperthyroidism; FNA not necessary

68
Q

Evaluation of a thyroid nodule: Next step if TSH is showed a “cold” nodule

A

Thyroid ultrasound

69
Q

Evaluation of a thyroid nodule: Next step if TSH is normal or elevated

A

Thyroid ultrasound

70
Q

Size cutoff for FNA of thyroid nodule

A

1cm

2015 ATA guidelines do not recommend FNA for any nodule <1cm unless metastatic cervical lymph nodes are present.

71
Q

TRUE OR FALSE: The use of levothyroxine to suppress serum TSH is effective in shrinking nodules in iodine-replete populations.

A

FALSE. The use of levothyroxine to suppress serum TSH is NOT effective in shrinking nodules in iodine-replete populations.

72
Q

Risk of malignancy if thyroid cytology is “I. Nondiagnostic or unsatisfactory”

A

1-5%

73
Q

Risk of malignancy if thyroid cytology is “II. Benign”

A

2-4%

74
Q

Risk of malignancy if thyroid cytology is “III. Atypia or follicular lesion of unknown significance (AUS/FLUS)”

A

5-15%

75
Q

Risk of malignancy if thyroid cytology is “IV. Follicular neoplasm”

A

15-30%

76
Q

Risk of malignancy if thyroid cytology is “V. Suspicious for malignancy”

A

60-75%

77
Q

Risk of malignancy if thyroid cytology is “VI. Malignant”

A

97-100%

Endocriknowlogy (9 decks)

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