This document provides an overview of the thyroid gland, including its anatomy, embryology, histology, physiology, common diseases and disorders. It discusses topics such as thyroid development, hormone production, hyperthyroidism and hypothyroidism, different types of thyroiditis including Hashimoto's, and thyroid tumors. The key information covered includes the location and blood supply of the thyroid, how it produces thyroid hormones and calcitonin, common signs and symptoms of overactive and underactive thyroid, and descriptions of Graves' disease, multinodular goiter, thyroid storm, and different forms of thyroiditis.

1. Thyroid

2. Objectives
 Anatomy
 Embryology
 Histology
 Metabolism
 Physiology
 Congenital Anomalies
 Hyperthyroidism
 Hypothyroidism
 Thyroiditis
 Thyroid Tumors
 Workup of Thyroid Masses

3. Embryology
The thyroid develops at the base of the tongue
between the first pair of pharyngeal pouches
(foramen cecum)
The thyroid gland then descends
It remains connected to the floor of the
 A pyramidal lobe (50–80%)

4. Embryology

5. Anatomy
Location and Level (C5-T1)
Blood Supply
Lymphatics
Closely Related Structures

6. Anatomy

7. Anatomy

8. Anatomy

9. Anatomy

10. Anatomy
 strap muscles neck “Infrahyoid muscles”
 All supplied by Ansa Cervicalis except thyrohyoid (by
thyrohyoid branch of the C1 via CNXII)

11. Anatomy
Ansa Cervicalis (Created by C1,2,3)

12. Anatomy
Ansa Cervicalis (Created by C1,2,3)

13. Anatomy

14. Anatomy

15. Anatomy

16. Anatomy
Non-recurrent laryngeal nerve

17. Histology

18. Metabolism

19. Metabolism

20. Metabolism

21. Physiology
 Production of hormones:
 Thyroid hormones (Follicular cells)
 Triiodothyronine “T3”
 Tetraiodothyronine “Thyroxine”“T4”
 Calcitonin (Parafollicular cells)
 Stimulated by high serum calcium
 Lowers the serum calcium by inhibiting
osteoclasts

22. Physiology

23. Physiology
 The release of TH into circulation within 30 minutes of
TSH stimulation
 2-3 month supply stored in colloid
 In plasma:
 T4(90%) and T3 (T4 5’-Deiodinase)
 Free T4 (0.1%) and T3
 T4 less active, longer half life (7d), T3 much more
active, shorter half life (1d)
 Thyroxine binding globulin( 25% saturated)
 If amount o thyroid-binding globulin (TBG)
changes, only total T4 changes, not free T4

24. Physiology
 Cardiovascular system: HR, CO , blood flow, blood
volume, widened pulse pressure
 Respiratory system: RR , tidal volume
 Gastrointestinal system: Increased motility
 Central nervous system: Temp. , Nervousness, anxiety
 Musculoskeletal system: Increased reactivity up to a
point, fine motor tremor
 Sleep: Constant fatigue but decreased ability to sleep
 Nutrition: BMR, need or vitamins, decreased weight

25. Common Symptoms
Swelling “Goiter”
Heat or cold- intolerance
Weight loss or gain
Increased or decreased appetite
Cardiovascular and/or respiratory symptoms
 Fatigue, weakness, apathy
Decreased libido, infertility
Menstrual abnormality

26. Goiter

27. Goiter

28. Congenital Anomalies
 Persistent sinus tract remnant of developing gland
(M.C.)
 Sistrunk’s operation
 Complete failure to develop
 Incomplete descent: Lingual or subhyoid position
 May be the only functioning thyroid
 Excessive descent: Substernal thyroid
 Malformation of branchial pouch

29. Thyroglossal Duct Cyst

30. Sistrunk’s operation

31. Goiter
 Swelling of the thyroid
 Classification:
 Simple “Euthyroid”:
 Dyshormonogenesis (M.C)
 Iodine Deficiency
 Physiologic
 Toxic “Hyperthyroid”:
 Grave’s Disease
 Plummer’s Disease
 Toxic Nodule

32. Goiter
 Inflammatory “Eu/Hypo/Hyper”:
 Acute pyogenic
 De Quervain's Disease
 Hashimoto’s Disease
 Riedel’s Fibrosing Thyroiditis
 Neoplastic “Eu/Hyper”:
 Primary vs Secondary “Mets, M.C RCC”
 Primary: According to cell of origin

33. Goiter
 Primary: According to cell of origin
 Follicular:
 Well differentiated:
I. Papillary
II. Follicular
III. Hurthle’s Cell
IV. Oncocytoma
 Poorly differentiated:
I. Anaplastic
 Parafollicular:
I. Medullary

34. Goiter
 Stromal :
I. Lymphoma (confused with
Hashimoto’s thyroiditis)
 Note: There are subtypes and mixed tumors

35. Goiter
 Nodular goiter DDx:
 Dominant nodule of MNG (50%)
 Follicular adenoma (25%)
 Malignancy (12.5%)
 Miscellaneous (12.5)
 Suspect nodule be malignant if:
 Old age, male, family history, radiation history
 Signs: hoarseness, pain radiating to the ear,
rapidly growing, skin ulceration, calcium
imbalance symptoms, MEN II

36. Goiter
 Indications of surgery:
 General: suspicion of malignancy, compression,
Follicular lesion on biopsy
 Specific:
 Cosmetic: Simple goiter, Thyroiditis
 Failure of medical treatment: Simple goiter,
Thyroiditis, Toxic goiter
 Retrosternal Thyroid: Any goiter
 Exophthalmos: Toxic goiter

37. Hyperthyroidism
 Definition:
 Overactive thyroid, elevated level of TH (T4 and T3)
with subsequent signs and symptoms of increased
thyroid function
 Primary: high T4, low TSH
 Secondary: high T4, High TSH

38. Hyperthyroidism

39. Hyperthyroidism
 Symptoms:
 CVS
 CNS
 Weight and appetite
 Sexual Dysfunction
 Sign:
 Neck Swelling
 Bruit
 Exophthalmos
 Pretibial myxedema

40. Hyperthyroidism
 DDX:
 Graves’ disease (M.C.)
 Toxic nodular goiter
 Toxic thyroid adenoma
 Subacute thyroiditis
 Functional metastatic thyroid cancer
 Struma ovarii

41. Graves’ disease
 Autoimmune disease caused by antibodies that activate
the TSHR on the follicular cells
 Risk Factors:
 Females
 Age (20-25y)
 Family history
 Associated with Other autoimmune diseases
 Diagnosis:
 Thyroid function tests (high T4 and T3, Low TSH)
 Radioactive iodide uptake test (RAIU)

42. Graves’ disease
 Treatment:
 Medical
 Radioablation
 Surgery
 Choosing the treatment depend on the individual
case (Age, severity, size, surgical risk, treatment side
effects, comorbidities)

43. Graves’ disease
 Radioablation:
 Indicated for small or medium-sized goiters, if
medical therapy has failed, or if other options are
contraindicated
 Euthyroid within 2 months
 Most patients ultimately require TH replacement
 Complications include exacerbation of thyroid storm
initially
 Contraindicated in pregnant patients, women of
childbearing age and newborns

44. Graves’ disease
 Surgical treatment:
 Total, Subtotal, Lobar removal
 Indicated when radioablation is contraindicated or if
medical management cannot be used
 Patients should be euthyroid prior to excision
 Advantage over radioablation is immediate cure
 Complication: RLN injury, Hypoparathyroidism,
persistent hyperthyroidism, transient
hyperparathyroidism (M.C)

45. Toxic Multinodular Goiter
 AKA “Plummer’s Disease”
 Etiology:
 Iodine deficiency
 mutation in the TSH receptor
 Diagnosis: Labs, Biopsy
 Treatment: Best is surgical because radioablation has
high rate of failure

46. Toxic Multinodular Goiter

47. Thyroid Storm
 AKA “Thyrotoxicosis”
 Caused by exacerbating factors that precipitate extreme
hyperthyroidism in a hyperthyroid patient
 inadequately prepared patient
 Infection
 Labor
 iodide administration
 recent radioablation

48. Thyroid Storm
 Signs and Symptoms:
 Fever, tachycardia, muscle stiffness or tremor,
disorientation/altered mental status
 50% of patients develop CHF
 Mortality rate of 20-40%
 Treatment:
 Best way is to AVOID it
 Fluids, Anti-thyroid medication, β-blockers,
corticosteroids, sodium iodide or Lugol’s solution “KI” ,
and cooling blanket

49. Thyroid Storm

50. Hypothyroidism
 AKA: Myxedema
 Definition: Underactive thyroid, low levels of T4 and
T3
 Signs and Symptoms: Differ depending on age
 In ants/pediatrics: Characteristic Down’s-like
faces, failure to thrive, mental retardation
 Adolescents/adults:
 CVS
 CNS
 Weight and appetite
 Sexual Dysfunction

51. Hypothyroidism
 Less common complaints: Yellow-tinged skin, hair loss,
tongue enlargement
 Reduced Reflex Relaxation time is a pathognomonic
 DDX:
 Autoimmune thyroiditis
 Iatrogenic: thyroidectomy, radioablation, secondary to
anti-thyroid medications
 Iodine deficiency

52. Hypothyroidism
 Diagnosis: by H&E and Labs
 low T4 and T3
 Primary VS Secondary
 TRH challenge
 Thyroid autoantibodies positive in autoimmune
thyroiditis
 Low hematocrit (Hct.)
 Treatment: PO Thyroxine

53. Hypothyroidism

54. Thyroiditis
 Inflammation of the thyroid gland
 May be infectious or autoimmune
 Could cause hyperthyroidism, hypothyroidism or
euthyroidism.

55. Thyroiditis
 Types:
 Acute
 Subacute “de Quervain’s Thyroiditis”
 Chronic “Hashimoto’s Thyroiditis”
 Riedel’s Fibrosing Thyroiditis

56. Acute Thyroiditis
 Infectious inflammation of the thyroid
 Causes: Strep pyogenes, Staph aureus,
Pneumococcus pneumoniae
 Risk actors: Female sex, goiter, thyroglossal duct
 Signs and symptoms: Unilateral neck pain, fever,
euthyroid state, dysphagia, tenderness
 Treatment: IV antibiotics and surgical drainage

57. Acute Thyroiditis

58. de Quervain’s Thyroiditis
 Subacute granulomatous inflammation of the thyroid
 Etiology: Post–viral upper respiratory infection
 Risk actors: Female sex
 Signs and symptoms: Fatigue, depression, neck pain,
ever, unilateral swelling of thyroid with overlying
erythema, firm and tender thyroid, transient
hyperthyroidism usually preceding hypothyroid phase

59. de Quervain’s Thyroiditis
 Diagnosis: Made by history and exam
 Treatment:
Usually self -limited disease (within 6 weeks)
Manage pain with (NSAID)
Ten percent o patients with subacute thyroiditis
become permanently hypothyroid, require
Thyroxine

60. de Quervain’s Thyroiditis

61. Hashimoto’s Thyroiditis
 AKA: Chronic Lymphocytic Thyroiditis
 Etiology: Autoimmune
 Risk actors: Down’s syndrome, Turner syndrome, familial
Alzheimer’s disease, history of radiation therapy as child
 Signs and symptoms: Painless enlargement of thyroid,
neck tightness, presence of other autoimmune diseases
 20% of patients with Hashimoto’s thyroiditis will be
hypothyroid at diagnosis. A euthyroid state is more
common

62. Hashimoto’s Thyroiditis
 Diagnosis: Made by history, physical, and labs
 Labs: Circulating antibodies against microsomal thyroid cell,
TH, T3,T4, or TSH receptor
 Pathology: Firm, symmetrical, enlargement; follicular and
Hürthle cell hyperplasia; lymphocytic and plasma cell
infiltrates
 Biopsy: Very similar to Hashimoto’s Thyroiditis

63. Hashimoto’s Thyroiditis
 Treatment:
 Thyroid hormone (usually results in regression of
goiter)
 With failure o medical therapy, partial thyroidectomy is
indicated
 If biopsy confirms lymphoma during surgery, there is
no need to remove the thyroid (very responsive to
chemotherapy)

64. Hashimoto’s Thyroiditis

65. Hashimoto’s Thyroiditis

66. Hashimoto’s Thyroiditis

67. Hashimoto’s Thyroiditis

68. Riedel’s Fibrosing
Thyroiditis
 Rare, fibrosis replaces both lobes and isthmus
 Risk actors: Associated with other fibrosing
conditions, like retroperitoneal fibrosis, sclerosing
cholangitis
 Signs and symptoms: Usually remain euthyroid; neck
pain, possible airway compromise; firm, non-tender,
enlarged thyroid
 Diagnosis: Open biopsy required to rule out
carcinoma or lymphoma

69. Riedel’s Fibrosing
Thyroiditis
 Pathology: Dense, invasive fibrosis of both lobes and
isthmus. May also involve adjacent structures
 Treatment:
 With airway compromise: Isthmectomy
 Without airway compromise: Medical treatment with
steroids.

70. Riedel’s Fibrosing
Thyroiditis

71. Thyroid Cancer
 Benign:
 Adenoma
 Four types of malignant thyroid
tumors:
 Papillary
 Follicular
 Medullary
 Anaplastic
 Risk Factors: History of radiation, family
history, age, gender.

72. Thyroid Cancer

73. Thyroid Cancer

74. Thyroid Cancer

75. Thyroid Cancer

76. Thyroid Cancer
 MEN II A “Sipple’s Syndrome”
 Medullary Thyroid cancer (100%)
 20% of MTC is due to MEN II
 Parathyroid hyperplasia (50%)
 Pheochromocytoma (33%)
 MEN II B:
 Mucosal Neuroma (100%)
 Medullary Thyroid Caner (85%)
 Pheochromocytoma (50%)
 Marfanoid Habitus

77. Thyroid Cancer
 Workup of a mass:
 Solitary nodule (15% malignant)
 Multiple nodules (5% malignant)
 90-95% are well differentiated
 Start with U/S and Lab tests, if not diagnostic, FNA is used:
 Benign(65%): follow on U/S and labs
 Malignant(15%): Surgery
 Suspicious

78. Thyroid Cancer
 Suspicious/Non-diagnostic(15%): obtain 123 I Scan
 85% cold nodule with 10-25% chance of malignancy
 5% hot nodule with 1% chance of malignancy
 Surgery if: serial T4 levels fail to regress or future biopsies are worrisome
 Tumor markers:
 Follicular: Thyroglobulin
 Parafollicular: Calcitonin

79. Thyroid Cancer
 Biopsy Findings:
 Papillary: Papillary projections (M.C) Psammoma bodies, orphan Anne eye
 Calcifications are seen only in papillary tumor

80. Thyroid Cancer
 Biopsy Findings:
 Follicular: Follicles with
capsular invasion
 FNA can never
differentiate between
follicular adenoma and
carcinoma

81. Thyroid Cancer
 Biopsy Findings:
 Anaplastic: highly cellular
undifferentiated cells
 Invade near by structures

82. Thyroid Cancer
 Biopsy Findings:
 Medullary: sheets of malignant
cells in an amyloid stroma
 Neuroendocrine cell that
produce many types of
hormones (commonly
calcitonin)

83. Thyroid Cancer
 Cancer surgery:
 Papillary: thyroidectomy with LN dissection, radioablation could be done
 <1.5cm: Hemithyroidectomy
 >1.5cm: Total thyroidectomy
 If LN positive: modified radical dissection
 The other lobe may be removed prophylactically
 Follicular: Thyroidectomy with radioablation of the remnant tissue
 <4cm: Hemithyroidectomy
 >4cm: Total thyroidectomy
 If LN positive: modified radical dissection

84. Thyroid Cancer
 Medullary: Total thyroidectomy with central neck LN dissection
 Anaplastic: Debulking surgery for relief of compression only “Isthmectomy”
 Lymphoma: Chemotherapy, no surgery
 Hemithyroidectomy: Lobe removal + isthmus removal
 Radioablation: Post operative thyroid hunger (at least 2wks) the diagnostic radioiodine
uptake test with (5mCi), if positive, treat with (125mCi). Repeat diagnostic test, if positive, give
(175mCi)

85. Thank You