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ENT endocrine disorders > Endocrine thyroid tumors > Flashcards

Endocrine thyroid tumors Flashcards

1
Q

How common are thyroid nodules?

A

Thyroid nodules are common; incidence is 50% in adults.

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2
Q

What is the most common pathology of a thyroid nodule?

A

Benign follicular adenoma

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3
Q

Why are thyroid nodules often found during pregnancy?

A

The incidence of thyroid nodules during pregnancy is 5 to 20%. Increased hormones and relative iodine deficiency may be associated with increased thyroid nodularity.

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4
Q

How often are thyroid nodules cancerous?

A

Approximately 5% are cancerous.

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5
Q

Is a thyroid cyst benign?

A

Not always. Malignancies such as papillary thyroid carcinoma and parathyroid carcinoma can be cystic.

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6
Q

What are the factors that increase suspicion of malignancy in a patient with a thyroid nodule?

A

Age younger than 20 years, male sex, family history of thyroid cancer, pheochromocytoma, hyperparathyroidism,
Gardner syndrome, Cowden disease, and a history of head
and neck radiation

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7
Q

Are thyroid nodules more likely to be malignant in

adults or in the pediatric population?

A

Pediatric. Approximately 5% of adult thyroid nodules are malignant and 20 to 50% of pediatric thyroid nodules are
malignant.

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8
Q

What is the most common cause of a thyroid nodule in the pediatric population?

A

Follicular adenoma, just as it is with adults

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9
Q

What signs and symptoms in a patient with a thyroid nodule are worrisome for cancer?

A

● Rapid growth, a solid and fixed lesion, lymphadenopathy,
pain, or compressive symptoms such as dysphagia or
stridor
● In addition, dysphonia may be secondary to compressive
symptoms or invasion of the recurrent laryngeal nerve.

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10
Q

What is the most common presentation of a patient with thyroid cancer?

A

Nontender, palpable thyroid mass

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11
Q

What are the ultrasound imaging characteristics of
a lymph node that are concerning for metastatic
thyroid cancer?

A

Loss of the fatty hilum, increased vascularity, rounded node

configuration rather than ovoid, hypoechogenicity of a solid nodule, microcalcifications, and peripheral vascularity

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12
Q

What is the value of PET imaging in thyroid

cancer?

A

PET imaging allows for initial staging of poorly differentiated thyroid cancer and tumor surveillance after treat-
ment of more advanced/metastatic thyroid cancer; it also
offers prognostic data for patients with known metastasis.

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13
Q

What are the subtypes of well-differentiated

thyroid cancer?

A

Papillary thyroid cancer, follicular thyroid cancer, and Hürthle cell thyroid cancer are all considered well-differentiated.

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14
Q

What are the most common staging systems available for well-differentiated thyroid cancer?

A

AJCC tumor node metastasis (TNM) classification system,
AMES (age, metastasis, extent of disease, size), AGES (age, grade, extent of disease, size), MACIS (metastasis, age,
completeness of surgical resection, invasion, size), Ohio
State University, and Memorial Sloan-Kettering Cancer
Center

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15
Q

Which tumor staging system for thyroid cancer includes gross resection of tumor in its prognostic
calculation?

A

Specimen size is included in the MACIS score, calculated by
the following formula: 3.1 (patient age < 40) or 0.08 x age
(patient ≥ 40) + 0.3 x tumor size (cm) + 1 (if extrathyroidal
extension) + 1 (if incomplete resection) + 3 (if distant
metastasis)

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16
Q

How does extrathyroidal extension impact thyroid cancer staging?

A

● T3: Any extrathyroidal extension
● T4a: Extrathyroidal invasion of subcutaneous soft tissue, larynx, trachea, esophagus, or recurrent laryngeal nerve
● T4b: Invasion of prevertebral fascia or encasement of the
carotid artery or mediastinal great vessels

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17
Q

How is age used in the AJCC TNM stage

classification for thyroid cancer?

A

There are different staging systems for patients younger
than 45 years compared with those who are 45 years old or greater. Patients over the age of 45 years generally have a
greater (worse) stage of disease than younger patients with
similar disease characteristics.

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18
Q

In which types of thyroid cancer are there different

staging systems based on age of the patient?

A

Papillary thyroid carcinoma and follicular carcinoma have separate staging criteria based on age. Medullary and
anaplastic carcinoma do not.

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19
Q

What is the most significant predictor of overall prognosis for well-differentiated thyroid cancer?

A

Distant metastasis is the most significant prognostic factor.

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20
Q

Review low-intermediate- and high-risk features

of well-differentiated thyroid carcinoma.

A

● Low risk: Localized disease without aggressive histologic
subtypes or vascular invasion; all macroscopic disease
removed at first surgery; no postoperative I-131 uptake
outside thyroid bed
● Intermediate risk: Microscopic tumor invasion outside the
thyroid bed, positive cervical lymph nodes, aggressive
histologic subtype or vascular invasion, and I-131 uptake
outside thyroid bed
● High-risk: Macroscopic extrathyroidal invasion, distant
metastasis, incomplete surgical resection, and elevated
postoperative thyroglobulin

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21
Q

Which risk factor most significantly increases the risk of thyroid carcinoma?

A

Exposure to ionizing radiation, especially as a child or

adolescent

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22
Q

What is the recommended surgical treatment for

patients with well-differentiated thyroid cancer?

A

Total thyroidectomy is recommended in cases of well-
differentiated thyroid carcinoma except in cases of papillary
thyroid carcinoma of low risk and < 1 cm in size. In this case,
a thyroid lobectomy is considered sufficient treatment by
many surgeons.

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23
Q

How should local invasion of the esophagus by

thyroid carcinoma be treated?

A

Local invasion of the pharynx or esophagus by thyroid
carcinoma should be resected and then repaired by primary
closure of the defect.

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24
Q

What adjuvant forms of treatment exist for well-

differentiated thyroid carcinoma?

A

TSH suppression with exogenous thyroid hormone, radio-
iodine ablation, or external beam radiation. Other treatments such as tyrosine kinase inhibitors may delay disease progression but have not been proven to increase survival.

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25
Q

What is TSH suppression?

A

Increased thyroxine levels administered to decrease the
concentration of TSH released by the pituitary gland. Side
effects of TSH suppression include bone loss, cardiac
arrhythmias, and symptoms of hyperthyroidism.

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26
Q

Why is radioiodine ablation treatment used after surgery?

A

To destroy microscopic residual disease

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27
Q

How does radioiodine ablation assist in long-term management of well-differentiated thyroid carcinoma?

A

Complete removal of microscopic and macroscopic disease
by surgery and adjuvant radioiodine ablation allows for
closer management of recurrence or persistent disease with thyroglobulin measurements and whole-body radioiodine scans.

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28
Q

What are the complications of radioiodine ablation?

A

Sialadenitis, dental caries, nasolacrimal duct obstruction,

xerostomia, and rarely secondary malignancies

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29
Q

What is the recommended treatment for well-

differentiated thyroid carcinoma found in a thyroglossal duct cyst?

A

A Sistrunk procedure is adequate in cases in which clinical
and radiologic examinations demonstrate normal thyroid and regional lymph nodes. Proceeding with total thyroidectomy should be considered in high-risk patients, as defined by age greater than 45 years, tumor diameter
greater than 4 cm, extracapsular spread, regional or distant
metastasis, or clinical or radiologic evidence of disease in the thyroid gland or regional lymph nodes.

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30
Q

How often do patients with thyroglossal duct cyst carcinoma have concurrent intrathyroidal cancer?

A

Based on a Mayo Clinic study from 1997, 33% of patients

with thyroglossal duct cyst carcinoma had concurrent intrathyroidal malignancy.

31
Q

What is the recommended treatment for a
pregnant woman with well-differentiated thyroid
carcinoma?

A

Surgical excision is recommended, either during the second

trimester or after delivery.

32
Q

Does thyroid cancer discovered during pregnancy behave differently from disease found in non-
pregnant females?

A

No, there is no difference.

33
Q

What are the recommendations for radioiodine

ablation in regard to women of childbearing age?

A

Pregnancy should be avoided for 12 months after radio-

iodine ablation.

34
Q

What is the treatment for locoregional metastatic

well-differentiated thyroid carcinoma?

A

Ideally, surgical excision. Radioiodine ablation, externalbeam radiation, or clinical trials, if available, may be considered.

35
Q

What is the treatment for well-differentiated

thyroid carcinoma with tracheal invasion?

A

Complete surgical resection is the best treatment. It may
include shaving tumor from the trachea or esophagus,
segmental tracheal resection and reanastomosis, or
laryngopharyngectomy.

36
Q

As a general rule, what is the best treatment for well-differentiated thyroid carcinoma with pulmonary metastasis?

A

I-131 radioiodine ablation therapy

37
Q

In a case of well-differentiated thyroid cancer, how should involvement of the recurrent laryngeal
nerve be managed?

A

If preoperative vocal cord function is normal, the nerve

should be left intact if at all possible.

38
Q

What are the two most sensitive tests for tumor surveillance after treatment of well-differentiated
thyroid carcinoma?

A

Blood thyroglobulin levels and neck ultrasound.
Thyroglobulin is a reliable marker in patients who do not
produce anti-thyroglobulin antibodies, as its production is a
marker for functioning thyroid tissue.

39
Q

How might anti-thyroglobulin antibodies affect

posttreatment thyroglobulin levels?

A

The antibodies can produce a falsely low level of thyroglobulin and its utility as a tumor marker becomes invalid.

40
Q

Describe the role of chemotherapy in treating well-

differentiated thyroid malignancies.

A

In well-differentiated thyroid cancers, there are no data to support the use of adjunctive chemotherapy, but doxorubicin may be used as a radiation sensitizer in patients undergoing external beam radiation therapy. Also, tyrosine kinase inhibitors have been used to improve progression-free survival but do not have a synergistic effect with radiation.

41
Q

Which age group most commonly has cervical and distant metastases in papillary thyroid carcinoma: adults or children?

A

Children more commonly manifest with advanced disease.

42
Q

What is the current recommended treatment for
papillary thyroid microcarcinoma (< 1 cm) isolated to one lobe without extracapsular extension, positive lymph nodes, or distant metastasis?

A

Thyroid lobectomy

43
Q

What should the detectable level of thyroglobulin
be after total thyroidectomy and postoperative
radioactive iodine therapy for advanced papillary carcinoma?

A

The goal is for an undetectable thyroglobulin level.

44
Q

What histologic features are unique to papillary thyroid carcinoma?

A

Psammoma bodies, which are concentric calcified structures, “Orphan Annie” eyes from large nuclear inclusions and nuclear grooves

45
Q

In regard to papillary thyroid carcinoma, which pathological variants carry a worse prognosis?

A

Tall cell variant, columnar cell variant, and diffuse sclerosing
variants of papillary thyroid carcinoma carry a worse
prognosis.

46
Q

What type of thyroid cancer is most common in

the pediatric population?

A

Papillary thyroid carcinoma

47
Q

How is papillary thyroid microcarcinoma defined?

A

Papillary thyroid carcinoma measuring 1 cm or smaller irrespective of extrathyroidal extension, lymph node metastasis, or distant metastasis

48
Q

How does papillary thyroid carcinoma tend to spread?

A

Papillary carcinoma has a predilection for spreading via
lymphatic channels within the thyroid gland, leading to
frequent multifocal disease, as well as to local lymph nodes
in the paratracheal and cervical regions.

49
Q

Is cervical lymph node metastasis more common in papillary or follicular thyroid carcinoma?

A

Papillary thyroid carcinoma. Cervical lymph node meta-

stases are present in 30 to 70% of patients.

50
Q

What is the effect of cervical lymph node metastasis on the prognosis of papillary thyroid cancer?

A

Currently, this topic is debatable, but most contend that there is no decrease in survival with local lymph node involvement. However, there is an increased risk of recurrence after surgical treatment.

51
Q

How is a follicular thyroid adenoma differentiated

from follicular thyroid carcinoma?

A

Surgical pathology is required to make the differentiation,
as carcinomas have capsular or vascular invasion. Follicular
thyroid carcinoma cannot be diagnosed with fine needle
aspiration.

52
Q

Are patients with follicular adenomas most commonly hyperthyroid, hypothyroid, or euthyroid?

A

Euthyroid

53
Q

Is distant metastasis more common in papillary or

follicular thyroid carcinoma?

A

Follicular thyroid carcinoma because it spreads via hematogenous dissemination

54
Q

Name the three categories of follicular thyroid carcinoma.

A

● Minimally invasive: Displays invasion of capsule but does
not invade through the capsule
● Moderately invasive: Has angioinvasion with or without
capsular invasion
● Widely invasive: Has invasion into extrathyroidal tissue

55
Q

For thyroid lobectomies with preoperative FNA
results of “indeterminate” or “follicular neoplasia
suspected,” what percentage of final pathology
results come back positive for follicular carcinoma?

A

Approximately 15 to 20%

56
Q

What is the significance of a pathology report

indicating aneuploid follicular carcinoma?

A

Aneuploid follicular carcinomas are more aggressive in their

behavior compared to other follicular carcinomas.

57
Q 
Describe the histopathologic findings of Hürthle
cell tumors (oncocytic neoplasms).
A

● Predominance of Hürthle cells, which are large, granular,
eosinophilic cells
● Malignancy is determined by the presence or absence of extracapsular spread, lymphovascular invasion, or presence of metastases.

58
Q

How do Hürthle cell carcinomas respond to radioiodine therapy?

A

Hürthle cell carcinomas tend to be aggressive and have decreased iodine uptake; thus, they are resistant to
radioiodine therapy.

59
Q

Medullary thyroid carcinoma accounts for what percent of all thyroid malignancies?

A

Approximately 5%

60
Q

Medullary thyroid carcinoma originates from what cell type?

A

Parafollicular cells (C cells) of the thyroid gland, which produce calcitonin and are of neuroendocrine origin

61
Q

What laboratory abnormalities are associated with

medullary thyroid carcinoma?

A

Elevated calcitonin and often elevated CEA

62
Q

What is the most common manifestation of medullary thyroid carcinoma?

A

● Patients with sporadic tumors usually have an enlarging
palpable neck mass and cervical lymphadenopathy.
● Patients with familial disease are often diagnosed in a
presymptomatic state as a result of early screening.

63
Q

What is the most important prognostic factor in

patients with medullary thyroid carcinoma?

A

Stage is the most important prognostic factor, followed by

age.

64
Q

How does radioiodine affect medullary thyroid carcinoma?

A

Medullary thyroid carcinoma does not take up radioiodine
because it originates from the parafollicular cells, which are
not involved in production of thyroid hormone.

65
Q

What is the recommended treatment for patients

with medullary thyroid carcinoma?

A

Minimum total thyroidectomy and central compartment
neck dissection are recommended. For patients with lateral
cervical node involvement or primary tumors larger than 1 cm, an ipsilateral level II through V neck dissection should
also be performed.

66
Q

What is the standard treatment for medullary thyroid carcinoma?

A

Total thyroidectomy with regional cervical lymph node
dissection. In patients with tumors greater than 1 cm, an
ipsilateral modified radical neck dissection should be
considered. Chemotherapy and radiation are not effective
treatments for medullary thyroid carcinoma.

67
Q

How common is anaplastic thyroid carcinoma?

A

It is the rarest form of thyroid cancer, representing less than 5% of thyroid malignancies.

68
Q

What is the age range of patients affected by

anaplastic thyroid cancer?

A

Most are over 70 years old, and rarely do patients younger

than 50 years have anaplastic thyroid carcinoma.

69
Q

What are common initial symptoms of anaplastic thyroid carcinoma?

A

It is a rapidly enlarging neck mass, often associated with

dyspnea, dysphagia, hoarseness, and pain.

70
Q

What is the relationship between anaplastic

thyroid cancer and well-differentiated thyroid cancer?

A

In some cases, anaplastic thyroid carcinoma may develop from a long-standing well-differentiated thyroid malignancy such as papillary thyroid carcinoma.

71
Q

What is the prognosis for anaplastic thyroid

cancer?

A

It is almost universally fatal within 6 to 12 months of diagnosis.

72
Q

What is an indication for surgery with anaplastic

thyroid cancer?

A

Although controversial, tumor debulking for palliation can be considered. In addition, small, contained cancers may be approached with intent to cure.

73
Q

What is a currently accepted protocol to treat anaplastic thyroid cancer?

A

Chemotherapy with doxorubicin, hyperfractionated radio-

therapy, and surgical debulking.

74
Q

In what type of thyroid cancer is external-beam radiation used most commonly?

A

External-beam radiation has been used with limited success in anaplastic carcinoma as a neoadjuvant therapy in surgically unresectable cases.

ENT endocrine disorders (5 decks)

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