Anatomy of Thyroid

1. Thyroid diseaseLibo Li MDDepartment of General SurgerySir Run Run Shaw HospitalSchool of medicine, Zhejiang University

2. Anatomy of Thyroid

3. Anatomy of Thyroid

4. Thyroid disease • Nontoxic goiter • Hyperthyroidism • Thyroid Cancer • Thyroiditis

5. Nontoxic Goiter • Goiter from the French (goitre) and Latin (guttur), both meaning throat • Defined as an enlargement of the thyroid gland • Endemic when it involves more than 10% of the population • The majority, secondary to iodine deficiency • Especially found in high mountain regions

6. Nontoxic GoiterClinical thinking • Whether the patient has local symptoms • Whether the goiter is toxic or nontoxic • Whether any of the nodules harbor a cancer • The number and bilaterality of the nodules • TSH level, differential diagnosis of hypothyroidism or hyperthyroidism • Appropriate treatment options for each particular patient

7. Nontoxic GoiterTaking history • Asymptomatic neck mass • A cough, shortness of breath, stridor, or hoarseness • Choking or aspiration, dysphagia, or pain • Symptoms of hyperthyroidism • Whether the patient has cosmetic concerns • From iodine deficiency region

8. Nontoxic GoiterPhysical examination • Whether the goiter is confined to the neck • Whether it has a substernal component • Whether tracheal deviation is present • The size and consistency of the goiter • The mobility of the vocal cords by either indirect or direct laryngoscopy

9. Nontoxic Goiter • Ultrasound • How many nodules? • Bilateral? • Ultrasound characteristics

10. Nontoxic Goiter • CT scan • Neck and chest, especially substernal thyroid • Rare intrathoracic or aberrant thyroid

11. Nontoxic Goiter • Fine needle aspiration (FNA) • Suspicious malignent goiter

12. Nontoxic GoiterTreatment • Iodine diet replacement (endemic goitor) • Surgical resection • Symptoms • Local compression • Secondary hyperthyroidisim • Any suspicious or malignant lesion • Cosmetic reasons • Radioiodine therapy, high risk of pts • Thyroid hormone suppression (not for sporadic goiter)

13. Sporadic Nontoxic Goiter • Asymptomatic • Euthyroid • Most bilaterally • No efficiency of thyroid hormone replacement • High recurrence postoperatively 30%~40%

14. Nontoxic GoiterHistory of Thyroid Surgery • First thyroidectomy, in Paris in 1791 by Pierre-Joseph Desault • Antisepsis, hemostasis, and general anesthesia in the 1840s • thyroid surgery became safe • Theodore Kocher, a Nobel Prize in 1909 • From Bern, Switzerland • His pioneering efforts in thyroid surgery

15. Primary HyperthyroidsimGrave’s Disease

16. Clinical Statistics • Graves Disease is the most common cause of hyperthyroidism (60-80%) of all cases • Females are affected more frequently than men 10:1.5 • Monozygotic twins show 50% concordance rates • Incidence peaks from ages 20-40 • Incidence is similar in whites and Asians, but is somewhat decreased for African Americans

17. Graves' Disease • Autoimmune systemic disorder • Thyroid receptor antibody binding to and stimulating the TSH receptor • Excessive synthesis and secretion of thyroid hormone • Usually diffusely and symmetrically enlarged and firm

18. Hyperthyroidism—uptake • A. Normal • B. Graves’ Dz • C. Toxic Multinodular Goiter • D. Toxic Adenoma • E. Thyroiditis

19. HyperthyroidismSymptoms • Heat intolerance, sweating, palpitations, fatigue • Weight loss, diaphoresis, increased stool frequency • Muscle weakness, anxiety, insomnia • Nervousness or restlessness; irritability, emotional lability • In women, irregular menses

20. HyperthyroidismClinical findings • Tremor, tachycardia (A. fib), • Goiter, lid lag, proptosis, periorbital edema, exophthalmos; chemosis; hyperreflexia • Warm, moist skin; dermopathy; and pretibial edema,osteoporosis

21. Lid Lag in Graves Disease Exopthalamos in Graves Disease

22. Hyperthyroidism—treatment • Beta-blockers: control sxs • Propranololdecr peripheral T4 -> T3 conversion • Graves’ Dz • PTU (safe in pregnancy) or methimazole • Rare side effect: agranulocytosis • Radioactive iodine • 75% of treated pts become hypothyroid • Surgery • Toxic Adenoma or TMNG • RAI or surgery

23. HyperthroidismSurgery • Surgical approach • Bilateral near-total or total thyroidectomy • Indication of surgery (In China) • Compressive symptoms • Secondary or adenoma • Recurrence of medicine or iodine-131 • No efficiency of medicine • Second trimester of pregnancy

24. Surgery for hyperthyroidismPreoperative preparation • Absolutely required • antithyroid drugs, for 3 to 6 weeks • with a goal of nearly normalizing the T3 and T4 • Propranolol or atenolol rapidly controls the adrenergic side effects of excess T4 and T3 • tachycardia, tremor, and diaphoresis • Lugol's solution rapidly but temporarily restores normal thyroid function and reduces thyroid gland vascularity

25. Surgical complications • Bleeding • Recurrent Laryngeal Nerve Damage • Hypoparathyroidism and Hypocalcemia • Superior laryngeal nerve damage • Thyroid storm

26. Thyroid cancer

27. Thyroid cancerIntroduction • The most common, 95% of all endocrine cancers • Increasing faster than any other cancer • More than 90% , well differentiated • Good long-term prognosis

28. Thyroid cancerClinical Presentation • Most, clinically with a palpable nodule • Usually asymptomatic • Rare cases, with hoarseness, pain, dysphagia, dyspnea, coughing, or choking spells • Pain，with the suspicion for • Medullary thyroid carcinoma • Anaplastic carcinoma • Lymphoma

29. Pertinent historical factors predicting malignancy • A history of head and neck irradiation • Total body irradiation for bone marrow transplantation • Exposure to fallout from the explosion of the Chernobyl nuclear power plant in 1986, especially in children; • A family history of thyroid cancer; and rapid growth or hoarseness. • Children, men, and adults older than 60 years have an increased risk of malignancy

30. Increase the risk of thyroid cancer • Personal and family history of other endocrine disorders, • specifically hyperparathyroidism, pituitary adenomas, pancreatic islet cell tumors, adrenal tumors, and breast cancer. • A family history of papillary or medullary carcinoma (MEN syndromes), familial polyposis, Gardner's syndrome, and Cowden's syndrome

31. Pertinent physical findings Suggesting possible malignancy • Gritty texture”(颗粒样） of the thyroid nodule • Cervical lymphadenopathy • Vocal cord paralysis • Fixation of the nodule to surrounding tissue

32. Thyroid cancerDiagnosis • Ultrasound • Feature of malignancy • Irregular margins • Intranodular vascular pattern • Microcalcifications • Fine needle aspiration (FNA) • The most reliable and cost-efficient method

33. Thyroid cancer Diagnosis • Thyroid function tests • Serum markers • Thyroglobulin (TG) for well-differentiated thyroid cancer • Calcitonin and CEA for medullary thyroid cancer • All pts with medullary thyroid cancer • RET proto-oncogene • pheochromocytoma and hyperparathyroidism

34. Management of thyroid cancer The goals of therapy • Removal of primary tumor, disease that extends beyond the thyroid capsule, and involved cervical lymph nodes • Minimization of treatment- and disease-related morbidity • Accurate disease staging • Facilitation of postoperative treatment with radioiodine when appropriate • Accurate long-term surveillance • Minimization of the risk of recurrent local and metastatic tumor

35. Well-Differentiated Thyroid CarcinomaPapillary Thyroid Carcinoma • The most common endocrine malignancy，approximately 80% of new cases • Associated with the best prognosis • At least twice as common in women as men • A peak age of presentation of 38 to 45 years • 90% of radiation-induced，familial in 5%

36. Papillary Thyroid Carcinoma

37. Well-Differentiated Thyroid CarcinomaPrognoses • The risk of death • approximately 5% in the low-risk group • 40% in the high-risk group • Fortunately, most pts (70%) in the low-risk group

38. Other histological factors • To predict the behavior of thyroid cancer • Ploidy of the tumor • Adenylate cyclase response to thyroid stimulating hormone (TSH) • Radioiodine uptake • A positive positron emission tomography scan • Epidermal growth factor (EGF) receptor level and various gene profiles

39. Papillary Thyroid CarcinomaThe extent of surgical resection • Controversial • American recommondation • Total or near total thyroidectomycomplication rate of less than 2% • Selective nodal resection • Postoperative treatment with iodine-131 • Low-risk pts less than 1 cm • thyroid lobectomy and isthmectomy OK • Reoperation • multifocal, with nodal metastases, or with local invasion

40. Benefits of total thyroidectomy • Postoperative radioiodine scanning and ablative therapy can be effective • Serum thyroglobulin levels are rendered more sensitive for detecting recurrent or persistent disease • Intrathyroidal cancer that is present in more than 50% of patients is removed • The small risk of a differentiated thyroid cancer becoming an undifferentiated cancer is decreased.

41. Papillary Thyroid CarcinomaThe role of lymph node dissection • Also controversial • Micrometastasis to cervical lymph nodes is common (80%) • Prophylactic cervical lymph node dissection is not warranted • Functional neck dissection and central neck dissection should generally be performed • only in pts with clinical or sonographic evidence of lymph node involvement

42. Follicular Thyroid Carcinoma • Approximately 10% of all thyroid malignancies • Typically older than PTC • Usually in the sixth decade of life • The female-to-male ratio is between 2:1 and 5:1 • A slowly growing solitary thyroid nodule • A tendency to spread hematogenously • Rarely with symptoms of distant metastasis to the bone, lung, brain, and liver

43. Follicular Thyroid Carcinoma • Less than 6% metastasize to the cervical lymph nodes • Approximately 25% of pts have extrathyroidal invasion • 10% to 33% have distant metastasis at the time of initial diagnosis

44. The prognosis of follicular cancer • Slightly worse than that for papillary cancer • Overall survival ranges from 43% to 95% at 10 years • Lifelong surveillance is not necessary

45. The prognosis of follicular cancer • The important prognostic factors • Presence of metastatic disease • Older age (usually >40 years) • Degree of invasion (microcapsular vs. angioinvasion with or without capsular and widely invasive) • Degree of tumor differentiation

46. Follicular Thyroid Carcinoma • Diagnosis • The whole specimen must be evaluated for vascular and capsular invasion. • Diagnosis of follicular cancer cannot be made on FNAB

47. Follicular Thyroid Carcinoma • Treatment • The recommended initial operation is lobectomy and isthmectomy • Lymph node dissection is rarely warranted because nodal metastases are uncommon

48. Medullary Thyroid Carcinoma • 7% of thyroid cancers • 15% of all thyroid cancer–related deaths • Approx 75% sporadic零星的, 25% hereditary • From c cells or parafollicular cells • Located laterally at the junction of the upper two thirds of the thyroid gland at approximately the level of the cricoid cartilage

49. Medullary Thyroid Carcinoma • In the sporadic form • Usually a single focus of malignancy • Unilateral disease in 85% of cases • In the hereditary form • Multifocal and bilateral in 90% of cases • C-cell hyperplasia

50. The hereditary forms of MTC