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Unit 5: Path - The Endocrine System > Thyroid Gland > Flashcards

Thyroid Gland Flashcards

1
Q

What is the functional unit of the thyroid?

A

Follicle (acini)

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2
Q

What are follicles filled with?

A

Thyroglobulin

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3
Q

What two types of cells are contained w/i the thyroid?

A

Follicular cells and parafollicular (C) cells

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4
Q

What is secreted by the C cells?

A

Calcitonin

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5
Q

Which of the thyroid hormones is the precursor and which is the active?

A

T4 and T3 respectively

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6
Q

What is thyroid agenesis?

A

Complete absence of the thyroid tissue

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7
Q

What is a goiter?

A

Thyroid enlargement

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8
Q

What is nontoxic goiter?

A

Thyroid enlargement without functional, inflammatory or neoplastic alterations

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9
Q

What type of goiter is thought to have genetic etiology?

A

Simple nodular thyroid enlargement

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10
Q

What is the early stage of nontoxic goiter?

A

Diffuse nontoxic goiter

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11
Q

What does multinodular nontoxic goiter reflect?

A

More chronic disease

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12
Q

What are the blood concentrations of thyroid hormone in a patient with nontoxic goiter?

A

T3 and T4 are normal! (Euthyroid)

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13
Q

What type of goiter causes hyperthyroidism?

A

Toxic goiter

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14
Q

What is hypothyroidism?

A

Clinical manifestation of thyroid hormone deficiency

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15
Q

What are the three main causes of hypothyroidism?

A

Defective thyroid hormone synthesis, Inadequate thyroid fn., Inadequate secretion of TSH by the pituitary/TRH by the hypothalamus

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16
Q

What are often the first Syx of hypothyroidism?

A

Fatigue, lethargy, sensitivity to cold, and inability to concentrate

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17
Q

What is the peculiar type of edema that occurs in patients w/ hypothyroidism?

A

Myxedema

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18
Q

What is the name of the severe agitation seen in hypothyroid patients?

A

Myxedema madness

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19
Q

What is the major effect on the heart caused by hypothyroidism?

A

Myxedema heart (dilated heart and pericardial effusion)

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20
Q

How does hypothyroid affect the bowels?

A

Decreased peristalsis can lead to constipation, fecal impaction and myxedema megacolon

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21
Q

What is primary hypothyroidism often a manifestation of?

A

Autoimmune disease

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22
Q

What is goitrous hypothyroidism?

A

Thyroid enlargement associated with hypothyroidism

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23
Q

What is endemic goiter?

A

Goitrous hypothryoidism due to dietary iodine deficiency

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24
Q

What is a commonly used bipolar medicine that is antithyroid and goitrogenic?

A

Lithium

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25
Q

What does excess iodide intake cause?

A

Iodide induced goiter

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26
Q

What is another term for congenital hypothyroidism?

A

Cretinism

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27
Q

What are the two overlapping clinical presentations of endemic cretinism?

A

Neurologic and hypothyroid cretinism

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28
Q

What is neurologic cretinism?

A

Features mental retardation, ataxia, spasticity, and deaf-mutism

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29
Q

What is believed to be the cause of congenital hypothyroid cretinism?

A

Iodine deficiency in late fetal life and neonatal period

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30
Q

What is hyperthyroidism?

A

Clinical consequence of excessive circulating thyroid hormone

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31
Q

What is the most common cause of hyperthyroidism in adults?

A

Graves Disease

32
Q

What is Graves disease?

A

AI disease characterized by Diffuse goiter, hyperthyroidism, exophthalmos, tachycardia, weight loss, demopathy

33
Q

Describe the pathogenesis of Graves disease.

A

AI disease in which Abs act as agonists on the thyroid and stimulate the TSH receptor increasing thyroid hormone production

34
Q

What cellular elements play a role in Graves disease? What cells are at low levels?

A

CD4+ T cells, Autoreactive B Cells; Low levels of suppressor CD8+ cells

35
Q

Graves Disease is shown. What are the typical findings in the uscopic analysis?

A

Depleted, pale, scalloped (“moth-eaten”) where it abuts epithelial cells.

36
Q

What is the cause of exophthalmos in Graves disease?

A

Enlargement of the orbital extraocular muscles swollen by mucinous edema, accumulation of fibroblasts and lymphocyte infiltration.

37
Q

What are typical findings on exam of a patient with Graves disease?

A
  • Intolerance to heat
  • Sweating
  • Exophthalmos
  • Tachycardia
38
Q

What does toxic multinodular goiter result from?

A

Functional autonomy of thyroid nodules

39
Q

What is toxic adenoma?

A

Benign, solitary hyperfunctioning thyroid neoplasm

40
Q

What at is seen in a thyroid with a toxic adenoma on an 131I scintiscan?

A

One hot spot with excessive I uptake and remaining atrophic gland

41
Q

What is thyroiditis?

A

A heterogenous group of inflammatory disorders of the thyroid gland

42
Q

What is the typical cause of acute thyroiditis?

A

Acute process such as an infection that generally spreads hematogenously

43
Q

What is the most common cause of goitrous thryoiditis in the US?

A

Hasimoto thyroiditis (Chronic Autoimmune Thyroiditis)

44
Q

Describe the basic pathogenesis of Hashimoto Thyroiditis

A
  1. CD4+ cells stimulate proliferation of autoreactive CD8 T cells, which attack thyrocytes
  2. CD4 cells also recruit autoreactive B cells to produce Abs
  3. These Abs block TSH action
45
Q

In what regions is Hashimoto Thyroiditis most common?

A

In regions where iodine intake is highest

46
Q

What are the three uscopic findings in Hashimoto Thyroiditis?

A
  1. Lymphocyte/Plasma cell infiltrate
  2. Destruction/atrophy of follicles
  3. Oxyphilic metaplasia of follicular epithelial cells (Hürthle or Askanazy cells)
47
Q

What is hyperthyroidism caused by Hashimoto Thyroiditis called?

A

Hashitoxicosis

48
Q

What is subacute thyroiditis caused by?

A

Viral infection

49
Q

Describe the pathogenesis of subacute thyroiditis (de Quervain Thyroiditis)

A
  1. Acute inflamm
  2. Uabscesses
  3. Patchy infiltrate of lymphos/plasmas/macros
  4. Released colloid elicits florid granulomatous rxn
50
Q

What finding on physical exam would suggest thyroiditis?

A

Tender and enlarged thyroid

51
Q

What does silent thyroiditis cause?

A

Transient hyperthyroidism

52
Q

How does silent thyroiditis differ from hashimoto thyroiditis?

A

No antithyroid antibodies or other evidence of autoimmune thyroiditis

53
Q

What are the gross and uscopic findings in a patient with Riedel Thyroiditis?

A
  • Gross: Stony hard and “woody”
  • Uscopic: Thyroid parenchyma is largely replaced by dense, hyalinized fibrous tissue and a chronic inflammatory infliltrate
54
Q

What is a follicular adenoma of the thyroid?

A

Benign neoplasm showing follicular differentiation

55
Q

Where do follicular adenomas frequently occur?

A

In iodine-deficient areas

56
Q

Where can thyroid malignancies develop in association with benign lesions?

A

Malignancies can develop w/i benign nodules

57
Q

How do follicular adenomas present on a radiolabeled I scan?

A

They present as a “cold” nodule

58
Q

What types of tumors are typically malignant?

A

“Cold” nonfunctioning nodules (but can benign as well)

59
Q

What is the most common thyroid cancer?

A

Papillary Thyroid carcinoma

60
Q

What are two major risk factors for papillary thyroid carcinoma?

A
  1. Iodine excess
  2. Radiation
61
Q

What somatic mutations are associated with Papillary Thyroid Carcinoma?

A
  • RET proto-oncogene - rearranged to RET/PTC oncogene
  • BRAF mutation
  • RAS mutation
62
Q

Papillary Carcinoma of the Thyroid. What are important diagnostic charactersitics in the histological section.

A
  • Nuclear atypia
  • Ground Glass (“Orphan Annie”) clear nuclei
  • Dense fibrosis
  • Calcospherites (psammoma bodies)
63
Q

Describe the typical metastatic spread of papillary thyroid carcinoma.

A

Typically invades lymphatics and spreads to regional cervical lymph nodes

64
Q

What is follicular thyroid carcinoma?

A

Purely follicular malignant tumor with no papillary or other elements

65
Q

What are the two divisions of follicular thyroid carcinoma?

A

Minimally invasive and invasive

66
Q

What is a key distiction b/w a follicular adenoma and follicular thyroid tumor?

A

FTC spreads thru the tumor capsule

67
Q

An follicular carcinoma of the thyroid is shown to have invaded a vein in the thyroid parenchyma. What is the Dx?

A

Invasic FTC

68
Q

From what is medullary thyroid carcinoma derived?

A

C Cells of the Thyroid

69
Q

What mutation do those with familial form medullary thyroid carcinoma have?

A

MEN mutations

70
Q

A disticntly vascular stroma with polygonal cells embedded in a collagenous framework is shown. Amyloid deposition is also observed. What is the Dx?

A

Medullary thyroid carinoma

71
Q

What a very conspicuous sign of Medullary Thyroid Carcinoma?

A

Stromal amyloid representing deposition of procalcitonin

72
Q

What is the precursor lesions to medullary thyroid carcinoma?

A

C-cell hyperplasia

73
Q

What is the Px of anaplastic thyroid carcinoma

A

Usually fatal

74
Q

What mutation is commonly seen in anaplastic thyroid carcinoma?

75
Q

Histo shows bizarre spindle and giant cells with polyploid nuclei and numerous mitoses. Dx?

A

Anaplastic thyroid carcinoma

76
Q

What markers are present in Anaplastic Thyroid carcinoma? What marker is not present?

A
  • Epithelial Membrane Antigen
  • Cytokeratins

TTF1 is negative

Unit 5: Path - The Endocrine System (6 decks)

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