thyroid neoplasms

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  • 1.Thyroid Neoplasms

2. Solitary Thyroid Nodule The majority of thyroid nodules are benign and do not require removal. Therefore, it is of utmost importance to determine which patients with solitary thyroid nodule would benefit from surgery. 3. History Details regarding the nodule, such as time of onset, change in size, Associated symptoms, such as pain, dysphagia, dyspnea, or choking, should be elicited. Pain is an unusual symptom and when present, should raise suspicion for intrathyroidal hemorrhage in a benign nodule, thyroiditis, or malignancy. Patients with medullary thyroid cancer may complain of a dull, aching sensation. 4. History A hx of hoarseness is worrisome because it may be secondary to malignant involvement of the recurrent laryngeal nerves. Most importantly, patients should be questioned regarding risk factors for malignancy, such as exposure to ionizing radiation and family history of thyroid and other malignancies associated with thyroid cancer. External Beam Radiation- The risk is maximum 20 to 30 years after exposure 5. Family History is a risk factor for the development of both medullary and nonmedullary thyroid cancer Familial medullary thyroid cancers occur in isolation or in association with other tumors as part of multiple endocrine neoplasia type 2 (MEN2) syndromes. Nonmedullary thyroid cancers can occur in association with other known familial cancer syndromes such as Cowden's syndrome, Werner's (adult progeroid) syndrome, and familial adenomatous polyposis. Nonmedullary thyroid cancers also can occur independently of these syndromes. 6. Physical Examination Thyroid masses move with swallowing and failure to observe the patient swallowing may lead one to miss a large substernal goiter. The thyroid gland is best palpated from behind the patient and with the neck in mild extension. The cricoid cartilage is an important landmark because the isthmus is situated just below it. Nodules that are hard, gritty, or fixed to surrounding structures, such as to the trachea or strap muscles more likely to be malignant. The cervical chain of lymph nodes should be assessed as well as the nodes in the posterior triangle. One should examine the patient for a Delphian node and pyramidal lobe situated just above the thyroid isthmus and cricoid cartilage. 7. Diagnostic Tests Fine-Needle Aspiration Biopsy single most important test in the evaluation of patients with thyroid masses can be performed with or without ultrasound guidance. Ultrasound guidance is recommended for nodules that are difficult to palpate and for complex, solid cystic nodules that recur after the initial aspiration. After FNA biopsy, the majority of nodules can be categorized into the following groups: benign (65%), suspicious (20%), malignant (5%), and nondiagnostic (10%). The incidence of false-positive results is approximately 1% and false-negative results occur in approximately 3% of patients. 8. Nondiagnostic, it should usually be repeated. Bloody FNA biopsy may also be reported as nondiagnostic and often indicates a follicular neoplasm. Benign lesions include cysts and colloid nodules. The risk of malignancy in this setting is less than 3%. Suspicious cytology- The risk of malignancy is 10 to 20%. Most are follicular or Hrthle cell neoplasms. Diagnosis of malignancy in this situation relies on demonstrating capsular or vascular invasion, features that cannot be determined via FNA biopsy. 9. FNA biopsy is also less reliable in patients who have a history of head and neck irradiation or a family history of thyroid cancer, because of a higher likelihood of multifocal lesions. There is little or no value in repeating an FNA biopsy for a follicular or Hrthle cell lesion, Repeat FNA biopsy can be useful for patients when the cytology has some abnormalities that suggest a papillary thyroid cancer, but not enough to make this diagnosis. 10. Laboratory Studies Serum TSH- Most patients with thyroid nodules are euthyroid. If a patient with a nodule is found to be hyperthyroid, the risk of malignancy is approximately 1%. Serum Tg levels cannot differentiate benign from malignant thyroid nodules unless the levels are extremely high, in which case metastatic thyroid cancer should be suspected. Useful in following patients who have undergone total thyroidectomy for thyroid cancer For serial evaluation of patients undergoing nonoperative management of thyroid nodules. Serum calcitonin levels should be obtained in patients with medullary thyroid cancer or a family history of medullary thyroid cancer (MTC) or MEN2. 11. Imaging Ultrasound is helpful for detecting nonpalpable thyroid nodules, for differentiating solid from cystic nodules, and for identifying adjacent lymphadenopathy. It also provides a noninvasive and inexpensive method of following the size of suspected benign nodules diagnosed by FNA biopsy. CT and MRI are unnecessary in the routine evaluation of thyroid tumors, except for large, fixed, or substernal lesions. Scanning the thyroid with 123I or 99mTc is rarely necessary, unless evaluating patients for "hot" or autonomous thyroid nodules. currently recommended in the assessment of thyroid nodules only in patients who have follicular thyroid nodules on FNA biopsy and a suppressed TSH. 12. Management Malignant tumors are treated by thyroidectomy Simple thyroid cysts resolve with aspiration in approximately 75% of cases, although some require a second or third aspiration. Unilateral thyroid lobectomy is recommended If the cyst persists after three attempts at aspiration. for cysts greater than 4 cm in diameter for complex cysts with solid and cystic components, because of higher incidence of malignancy (15%). When FNA biopsy is used in complex nodules, the solid portion should be sampled. 13. If a colloid nodule is diagnosed by FNA biopsy, patients should still be observed with serial ultrasound and Tg measurements. If the nodule enlarges, repeat FNA biopsy is often indicated. l-thyroxine in doses sufficient to maintain a serum TSH level between 0.1 and 1.0 U/ mL may also be administered. Most effective for nodules smaller than 3 cm. Previous irradiation of the thyroid gland or who has a family history of thyroid cancer total or near-total thyroidectomy High incidence of thyroid cancer (40%) and decreased reliability of FNA biopsy in this setting. 14. Papillary Carcinoma 80% of all thyroid malignancies in iodine-sufficient areas The predominant thyroid cancer in children and individuals exposed to external radiation. Occurs more often in women, with a 2:1 female: male ratio; The mean age at presentation is 30 to 40 years. Most patients are euthyroid and present with a slowgrowing painless mass in the neck. Dysphagia, dyspnea, and dysphonia are usually associated with locally advanced invasive disease. Lymph node metastases are common, especially in children and young adults, and may be the presenting complaint. 15. The so-called "lateral aberrant thyroid" almost always denotes a cervical lymph node that has been invaded by metastatic cancer. Suspicion of thyroid cancer often originates through physical examination of the patient and a review of the patient's history. Diagnosis is established by FNA biopsy of the thyroid mass or lymph node. Distant metastases are uncommon at initial presentation, but may ultimately develop in up to 20% of patients. The most common sites are the lungs, followed by bone, liver, and brain. 16. Pathology Gross - hard and whitish and remain flat on sectioning with a blade, in contrast to normal tissue or benign nodular lesions that tend to bulge. Macroscopic calcification, necrosis, or cystic change may be apparent. Histologically- may exhibit papillary projections, a mixed pattern of papillary and follicular structures, or a pure follicular pattern (follicular variant). The diagnosis is established by characteristic cellular features. Cells are cuboidal with pale, abundant cytoplasm, "grooving," crowded nuclei, and intranuclear cytoplasmic inclusions, leading to the designation of Orphan Annie nuclei, which allows diagnosis by FNA biopsy. Psammoma bodies, which are microscopic, calcified deposits representing clumps of sloughed cells, may be present. 17. Mixed papillaryfollicular tumors and follicular variant of papillary carcinoma are classified as papillary carcinomas because they act biologically as papillary carcinomas. Multifocality - in up to 85% of cases. It is associated with an increased risk of cervical nodal metastases Rarely invade adjacent structures such as the trachea, esophagus, and recurrent laryngeal nerves. Other variants of papillary carcinoma (approximately 1% of all papillary carcinomas) include tall cell, insular, columnar, diffuse sclerosing, clear cell, trabecular, and poorly differentiated types. They are generally associated with a worse prognosis 18. Prognostic Indicators In general, patients with PTC have an excellent prognosis with a greater than 95% 10-year survival rate. AGES scoring system, which incorporates age, histologic grade, extrathyroidal invasion and metastases, and tumor size to predict the risk of dying from papillary cancer. The MACIS scale- metastases, age at presentation, completeness of original surgical resection, extrathyroidal invasion, and size of original lesion AMES system 19. Papillary or Follicular Tumors Stage Younger than age 45 Years I II Age 45 Years and older I II III IVA IVB IVC Medullary Thyroid Cancer Stage I II III IVA IVB IVC Anaplastic Cancer Stage IVA IVB IVCTNM Any T, Any N, M0 Any T, Any N, M1 T1, N0, M0 T2, N0, M0 T3, N0, M0; T1-3, N1a, M0 T4a, N0-1a, M0; T1-4a, N1b, M0 T4b, Any N, M0 Any T, any N, M1 TNM T1, N0, M0 T2-3, N0, M0 T1-3, N1a, M0 T4a, N0-1a, M0; T1-4a, N1b, M0 T4b, any N, M0 Any T, Any N, M1 TNM T4a, Any N, M0 T4b, Any N, M0 Any T, Any M, M1 20. Definitions Primary tumor (T) TX = Primary tumor cannot be assessed