American Thyroid Association Guidelines – Flashcards
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RECOMMENDATION 1: What is the role of thyroid cancer screening in people with familial follicular cell-derived Differentiated Thyroid Cancer?
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1) Screening people with familial follicular cell-derived DTC may lead to an earlier diagnosis of thyroid cancer, but there is no evidence that this would lead to reduced morbidity or mortality 2) 5-10% of DTC have a familial occurrence
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Pertinent Historical factors predicting thyroid malignancy
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1. History of childhood H/N radiation therapy 2. Total body radiation for bone marrow transplantation 3. Exposure to ionizing radiation from fallout in childhood or adolescence 4. Familial thyroid carcinoma or thyroid cancer syndrome (PTEN hamartoma tumor syndrome [Cowden's disease], FAP, Carney complex, Werner syndrome/progeria, MEN 2, risk for Medullary thyroid cancer in a first degree relative) 5. Rapid nodule growth 6. Hoarseness
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Pertinent Physical exam findings suggesting possible thyroid malignancy
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1. Vocal cord paralysis 2. Cervical lymphadenopathy 3. Fixation of the nodule to the surrounding tissue
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Syndromes Associated with Differentiated Thyroid Cancers
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1) PTEN - phosphatase and tensin homolog 2) Cowden's disease (Hamartoma tumor syndrome) 3) Familial adenomatous polyposis (FAP) 4) Carney complex 5) MEN 2 6) Werner syndrome/progeria
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Thyroid Nodule Guidelines
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1) Non palpable nodules discovered on U/S or some other imaging = incidentalomas - have same risk of CA as do sonographically confirmed palpable nodules of the same size 2) Generally, only nodules > 1cm should be evaluated 3) Occasionally, there may be nodules < 1cm may require further eval bcs of sxs or associated lymphadenopathy. Highly unlikely. 4) Most thyroid nodules are low risk.
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RECOMMENDATION 2: What is the appropriate laboratory and imaging evaluation for pts with clinically or incidentally discovered thyroid nodules?
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1) TSH should be measured during the initial evaluation of a pt with a thyroid nodule a. With discover of nodule > 1cm in any diameter, get TSH 2) If the serum TSH is subnormal, a radionuclide (preferably I(123) thyroid scan should be performed. 3) If the TSH is normal or elevated, a radionuclide scan should not be performed as the initial imaging evaluation.
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Physical Exam Findings Suggesting Malignancy
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1) Vocal cord paralysis 2) Cervical lymphadenopathy 3) Fixation of the nodule to the surrounding tissue
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I(123) Thyroid Scan Findings
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1) Obtain when the TSH is subnormal 2) Results a. Hyperfunctioning - rarely harbor CA. If hyperfunctioning nodule corresponds to one in question, don't need FNA bx b. Isofunctioning (warm) c. Non functioning (cold) 3) Note: if overt subclinical hyperthyroidism is present, additional eval is required 4) Elevated TSH, even within the upper part of the normal range, is assoc with increased risk of malignancy in a thyroid nodule and more advanced stage of thyroid CA
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Pertinent Historical Factors Predicting Thyroid Malignancy
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1) H/O childhood H/N Radiation Therapy 2) h/o Total body radiation for bone marrow transplantation 3) Exposure to ionizing radiation from fallout in childhood or adolescence 4) Familial thyroid carcinoma or thyroid cancer syndrome (PTEN hamartoma tumor syndrom [Cowden's disease], FAP, Carney complex, Werner's syndrome/progeria, MEN 2 5) Rapid nodule growth 6)Hoarseness 7) A higher TSH level, even within the upper part of the reference range is associated with increased risk of thyroid CA
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RECOMMENDATION #3: Routine measurement of serum thyroglobulin (Tg) for initial evaluation of thyroid nodules
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Not recommended. Serum Tg levels can be elevated in most thyroid diseases and are an insensitive and non specific test for thyroid cancer
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RECOMMENDATION #4: Routine serum calcitonin measurement
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No recommendation - insufficient evidence for or against
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RECOMMENDATION #5: PET positive thyroid nodule
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1) Focal FDG-PET uptake within a sonographically confirmed thyroid nodule conveys an increased risk of thyroid cancer. FNA is recommended for those nodules > 1 cm. Risk of malignancy is approx 35% 2) Diffuse FDG-PET uptake in conjunction with sonographic and clinical evidence of chronic lymphocytic thyroiditis does not require further imaging or FNA. Diffuse thyroid uptake most often benign. Diffuse PET uptake in thyroid - get an U/S 3) PET + thyroid nodules < 1cm that do not meet FNA criteria can be monitored similarly to thyroid nodules with high risk patterns that do not meet FNA criteria
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RECOMMENDATION #6: When to survey cervical lymph nodes
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Thyroid U/S with cervical lymph node survey should be performed in all pts with known or suspected thyroid nodules, nodular goiter, or nodule suggested/incidentally noted on another imaging study (MRI, CT, PET, Scintigriphy, etc)
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RECOMMENDATION #7: When to perform an FNA biopsy
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FNA is the procedure of choice in the evaluation of thyroid nodules, when clinically indicated. FNA is the most accurate and most cost effective method to eval thyroid nodules.
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RECOMMENDATION #8: Which nodules do you biopsy?
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1) Nodules >/= 1cm in greatest dimension with high suspicion sonographic pattern. 2) Nodules >/= 1 cm in greatest dimension with intermediate suspicion sonographic pattern 3) Nodules >/= 1.5cm in greatest dimension with intermediate suspicion sonographic pattern
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Consider FNA biopsy for the following thyroid nodules (Weaker evidence)
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1) Nodules >/= 2cm in greatest dimension with very low suspicion sonographic pattern (spongiform). 2) Observation is also a reasonable alternative
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FNA biopsy not required for the which type of nodules?
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1) Nodules that do not meet the stated criteria for biopsy 2) Nodules that are purely cystic
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U/S Features of thyroid nodules associated with thyroid cancer
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1) Microcalcifications. a. Macrocalcification mixed with microcalcification confers same risk as micro alone b. Interrupted periperal Ca with a soft tissue rim outside the Ca = malignant 2) Nodule hypoechogenicity compared with surrounding thyroid or strap muscles 3) Irregular margins (infiltrative, microlobulated, or Spiculated) 4) Shape taller than wide as measured on the transverse view Note: Poorly defined margins are not equivalent to irregular margins 5) Malignant nodules are almost always solid. Partially cystic = lower risk of malignancy
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High Suspicion Thyroid Nodule Characteristics
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1) Est Risk of CA: 70-90% 2) Nodule Characteristics - solid hypoechoic nodule or solid hypoechoic component of a partially cystic Nodule with one or more of the following features: a. Irregular margins (infiltrative, microlobulated) b. Microcalcifications c. Taller than wide shape d. Rim calcification e. Rim calcifications with small extrusive soft tissue component f. Extrathyroidal extension g. Any of the above with suspicious assoc lymph nodes 3) FNA size cutoff: FNA >/= 1cm
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Intermediate Suspicion Thyroid Nodule Characteristics
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1) Est Risk of CA: 10-20% 2) Hypoechoic solid nodule with smooth margins without: a. Microcalcifications b. Extrathyroidal extension c. Taller than wide shape 3) FNA size cutoff: FNA >/= 1cm
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Low Suspicion Thyroid Nodule Characteristics
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1) Est Risk of CA: 5-10% 2) Isoechoic or hyperechoic solid nodule, or partially cystic nodule with eccentric solid areas without: a. Microcalcification b. Irregular margins c. Extrathyroidal extension d. Taller than wide shape 3) FNA size cutoff: FNA >/= 1.5cm
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Very Low Suspicion Thyroid Nodule Characteristics
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1) Est Risk of CA: /= 2cm. Observation without FNA is also a reasonable option.
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Benign Thyroid Nodule Characteristics
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1) Est Risk of CA: < 1% 2) Purely cystic nodules (no solid component) 3) FNA: Do not biopsy 4) Consider aspiration with/without ethanol ablation if large and symptomatic
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When should an U/S evaluation of the Cervical Lymph Nodes be Performed?
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1) Should perform an U/S of the Central and anterior lymph node compartments whenever thyroid nodules are detected. 2) This should be done in conjunction with the Thyroid U/S.
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What should be done if Suspicious Cervical Lymph nodes Are noted During Thyroid/Cervical U/S
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1) FNA the suspicious lymph node + washout for Tg measurement if indicated 2) Should also perform U/S guided FNA bx of any sub centimeter thyroid nodules likely to represent the primary tumor based on sonographic features.
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Intranodular Vascularity - What is It's Significance?
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1) Not an independent predictor of malignancy for hypoechoic nodules 2) Can be an indicator of CA in iso and hyperechoic nodules. a. Only FNA these nodules if >/= 1.5cm
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U/S Features of Lymph Nodes Predictive of Malignant Involvement
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1) Microcalifications 2) Cystic aspect 3) Peripheral vascularity 4) Hyperechogenicity 5) Round shape
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When Is a Conservative Approach To Management of Thyroid Nodules Indicated/Considered?
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1) Conservative Approach = active surveillance as an alternative to FNA (Observe without FNA) 2) Patients with very low risk tumors - no clinical or radiographic evidence of invasion or mets 3) Patients with high surgical risk 4) Patients with a relatively short life span expectancy in whom the benefits of intervention may be unrealized
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RECOMMENDATION 9: Bethesda System for Reporting Thyroid Cytopathology - Should be used
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1) Nondiagnostic or Unsatisfactory a. Risk of Malignancy = 20% 2) Benign (55-74%) a. ROM = 2.5% 3) Atypia of Undetermined significance or Follicular lesion of Undetermined Significance (2-18%) a. ROM = 14% 4) Follicular Neoplasm or Suspicious for a Follicular Neoplasm (Includes Hurthle Cell/Suspicious for Hurthle cell neoplasm) [2-25%] a. ROM = 25% 5) Suspicious for Malignancy (1-6%) a. ROM = 70% 6) Malignant (2-5%) a. ROM = 99%
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RECOMMENDATION 10: What should be done for a thyroid nodule with an initially non diagnostic FNA cytology result?
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1) FNA should be repeated with with U/S and, if available, on site cytology eval 2) Repeatedly non diagnostic nodules without a high suspicion U/S pattern require close observation or lobectomy for path dx 3) Lobectomy should be considered if a. Nondiagnostic nodule has high suspicion U/S pattern b. Growth of the nodule > 20% in 2 dimensions during surveillance c. If clinical risk factors for CA are present 4) 3 month waiting period for f/u FNA after an initial non diagnostic FNA isn't necessary 5) Repeat FNA after nondiagnostic FNA will yield a diagnostic specimen 60-80% of time, especially if cystic component is < 50% of the nodule
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Risk of Malignancy in a nodule with a non diagnostic FNA bx result.
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1) Most are benign 2) ROM = 2-4% 3) ROM by U/S Features in pt with 2 non diagnostic FNA biopsies a. Microcalcifications, irregular margins, taller than wide shape, or hypoechogenicity = 25% b. Lacking above features = 4%
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RECOMMENDATION 11: What should be done to a nodule that is benign on FNA cytology?
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1) If FNA is negative, no further immediate studies/treatment are required a. ROM in a nodule with a prior benign FNA = 1-3% b. An initially benign FNA confers a negligible mortality risk during long term f/u despite risk of false negative FNA
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What to do with nodules > 3 - 4 cm?
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1) Some people offer lobectomy to patients with nodules > 3 - 4 cm in diameter, but there is no good science to back up 2) Risk of mortality from a false negative FNA biopsy is very low 3) ROM is approximately 10%
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RECOMMENDATION 12: What should be done if the FNA cytology result is diagnostic for primary thyroid malignancy?
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1) Surgery is generally recommended 2) Consider active surveillance in the following pts a. Pt with very low risk tumor (Papillary micro CA without clinically evident mets or invasion, no cytologic evidence of aggressive dz) b. Pt with high surgical risk bcs of comorbid conditions c. Pt with short remaining life span (serious cardiopulmonary dz, other malignancies, very advanced age) d. Pt with concurrent medical or surgical issues that need to be addressed prior to thyroid surgery
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Papillary microcarcinoma
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1) Def - tumor 1cm or less 2) Following surgery for Micro CA a. Dz specific mortality rate < 1% b. Locoregional recurrence rate = 2-6% c. Distant recurrence rate = 1-2% d. There is similar rates as above if no surgery is done e. Active surveillance with delayed surgery (done for enlargement or mets) does not affect survival in Papillary Micro CA - this is not generally done outside of Japan (Most get surgery for + FNA bx)
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Positive Predictive Value and Negative Predictive Value of FNA biopsy
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1) PPV of malignant FNA bx = 98.6% 2) NPV of benign cytologic dx = 96.3%
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RECOMMENDATION 13: Molecular testing on FNA cytology for the AUS/FLUS (Indeterminant) nodule.
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There is currently no single optimal molecular test that can definitively rule in or rule out malignancy in all cases of indeterminate cytology
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RECOMMENDATION 15: How to manage thyroid nodules with AUS/FLUS cytology
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1) After considering worrisome clinical and U/S features, repeat FNA or Molecular testing may be used to supplement malignancy risk assessment 2) If repeat FNA, molecular testing, or both are not performed or inconclusive, either surveillance or lobectomy may be performed depending on clinical risk factors, U/S patterns, and pt preference 3) AUS/FLUS = 7% of all FNA specimens 4) Risk of CA in AUS/FLUS = 16%
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RECOMMENDATION 16: Approach to the Follicular Neoplasm/Suspicious for Follicular Neoplasm FNA bx result
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1) Diagnostic surgical excision is the long established standard of care for management of FN/SFN Cytology 2) U/S features and molecular testing may be used to supplement malignancy risk assessment in FN/SFN thyroid nodule 3) If molecular testing is not performed or is inconclusive, surgical excision of the FN/SFN thyroid nodule
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Follicular Neoplasm/Suspicious for Follicular Neoplasm FNA results - Risk of Malignancy
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15-30%
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RECOMMENDATION 17: What should be done for FNA Cytology reported as Suspicious for Papillary Carcinoma?
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1) This is an indication for surgery. Surgical management should be similar to that of malignant cytology depending on clinical factors, pt preference, etc. 2) Est. ROM: 60-75% 3) Mutational testing for BRAF or the 7 gene mutation panel may be considered in nodules with suspicious cytology if this would be expected to alter surgical decision making
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RECOMMENDATION 18: What is the utility of PET scanning to predict malignant or benign disease when FNA cytology is indeterminate (AUS/FLUS, FN, SUSP)?
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FDG-PET imaging is not routinely recommended for the evaluation of thyroid nodules with indeterminate cytology.
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RECOMMENDATION 19: What is the appropriate operation for cytologically indeterminate thyroid nodules?
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When surgery is considered for a solitary, cytologically indeterminate nodule, thyroid lobectomy is the recommended initial approach. This approach may be modified based on clinical or U/S characteristics, pt preference, and/or molecular testing.
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RECOMMENDATION 20: When is appropriate to perform a total thyroidectomy for a cytologically indeterminate unilateral thyroid nodule?
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Because of increased risk of CA, total thyroidectomy is preferred in pts with indeterminate nodules with the following characteristics: a. Cytologically suspicious for CA b. Positive for known mutations specific for CA c. Suspicious U/S characteristics d. Large nodules (> 4cm) e. Pts with h/o familial thyroid CA or h/o Radiation exposure if completion thyroidectomy would be recommended based on the indeterminate nodule being malignant following lobectomy.
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What is to be done for patient's with an indeterminate nodule with bilateral nodular disease?
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The following may undergo total thyroidectomy when they have an indeterminate nodule and bilateral nodular thyroid dz 1) Pts with significant medical comorbidities 2) Pts who want to avoid the possibility of requiring a future surgery on the contralateral lobe Note: Total thyroidectomy can be performed on the above assuming completion thyroidectomy would be recommended if the indeterminate nodule proved malignant following lobectomy
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Goal of thyroid surgery for a thyroid nodule that is cytologically indeterminate (AUS/FLUS, FN, or SUSP).
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1) Establish histological dx and definitive removal 2) Reduce risks associated with remedial surgery in the previously operated field if the nodule proves to be malignant
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Which operations are inappropriate for possible thyroid cancers?
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1) Removal of the thyroid nodule alone 2) Partial lobectomy 3) Subtotal thyroidectomy
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What is the risk of post op hypothyroidism following a thyroid lobectomy?
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1) 22% biochemical 2) 4% risk of overt hypothyroidism
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How should multinodular goiter be evaluated for malignancy?
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1) Pts with multiple nodules > 1cm should be evaluated in the same way as pts with a solitary nodule > 1cm except that each nodule that is > 1cm carries an independent risk of malignancy and therefore multiple nodules may require FNA 2) When multiple nodules > 1cm are present, FNA should be performed preferentially based upon nodule sonographic pattern and respective size cutoff. 3) If none of the nodules has a high or moderate suspicion U/S pattern, and multiple sonographically similar very low or low suspicion pattern nodules coalesce with no intervening normal parenchyma, ROM is low and it is reasonable to aspirate the largest nodules >/= 2cm or continued surveillance without FNA.
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Multinodular Goiter definition
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Two or more clinically relevant nodules
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RECOMMENDATION 22: How to approach MNG in pt with low or low normal serum TSH.
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1) Low or low-normal TSH in pt with MNG may suggest that some nodules may be autonomous. 2) I (123) scan should be considered and directly compared to U/S image to determine functionality of each nodule >/= 1cm 3) FNA bx should be then considered for those isofunctioning or non functioning nodules. 4) The iso/non functioning nodules should be aspirated preferentially if they have high suspicion U/S pattern
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Risk of Malignancy in MNG
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1) Patients with multiple nodules have the same risk of malignancy as those with solitary nodules. 2) An U/S should be performed to evaluate U/S risk pattern for each nodule 3) Multiple thyroid nodules >/= 1cm may require aspiration based on U/S pattern 4) Radionuclide scanning may also be considered with MNG with goal of IDing appropriate hypofunctioning nodules
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RECOMMENDATION 23 (1/5): How to f/u thyroid nodules with benign FNA Cytology - how to determine which nodules to follow.
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F/U of Thyroid nodules with benign cytology should be determined by risk stratification based on U/S pattern
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RECOMMENDATION 23 (2/5): How to follow thyroid Nodules with high suspicion U/S features and benign FNA cytology
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Nodules with high suspicion U/S pattern - repeat U/S and U/S guided FNA bx within 12 months
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RECOMMENDATION 23 (3/5): How to follow thyroid Nodules with low to intermediate suspicion U/S pattern and benign FNA cytology
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Nodules with low to intermediate suspicion U/S pattern - repeat U/S at 12-24 months. If U/S evidence of grown (20% increase in at least 2 nodule dimensions with a minimal increase of 2mm or more than a 50% change in volume) or development of new suspicious U/S features, the FNA could be repeated or observation continued with repeat U/S, with repeat FNA in case of continued growth.
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RECOMMENDATION 23 (4/5): How to follow thyroid nodules with very low suspicion U/S pattern and benign FNA cytology
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Nodules with very low suspicion U/S pattern (including spongiform nodules) - the utility of surveillance U/S and assessment of nodule growth as an indicator for repeat FNA to detect a missed malignancy is limited. If U/S is repeated, it should be done at >/= 24 months.
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RECOMMENDATION 23 (5/5): How to follow a thyroid nodule with 2 previous benign FNA biopsies
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If a nodule has undergone repeat U/S guided FNA with a second benign cytology result, U/S surveillance for this nodule for continued risk of malignancy is no longer indicated.
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What is the False Negative rate of a benign cytology FNA bx?
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1.1%
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How to f/u thyroid nodules with an initial benign FNA cytology result
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F/U of benign cytology FNA nodules should be based on the nodule U/S pattern rather than growth. Larger nodules may require monitoring for growth that could result in symptoms and thus prompt surgical intervention despite benign cytology.
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RECOMMENDATION 24 (1/4): How should nodules that do not meet criteria for FNA bx, but have a suspicious U/S pattern at initial imaging be followed?
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Repeat U/S in 6-12 months
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RECOMMENDATION 24 (2/4): How should thyroid nodules that do not meet criteria for FNA bx, but have a low to intermediate suspicion U/S pattern at initial imaging be followed?
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Consider repeat U/S at 12-24 months
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RECOMMENDATION 24 (3/4): How should thyroid nodules that do not meet criteria for FNA bx, but are >/= 1cm with a very low suspicion U/S pattern (including spongiform nodules) and pure cysts be followed?
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The utility and time interval of surveillance U/S for risk of malignancy is not known. If U/S is repeated, it should be at >/= 24 months.
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RECOMMENDATION 24 (4/4): How should you follow nodules </= 1cm with very low suspicion U/S pattern (including spongiform nodules) and pure cysts be followed?
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They do not require routine sonographic f/u.
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What percentage of adults have thyroid nodules?
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1) Up to 50% of adults have thyroid nodules. 2) The vast majority of these nodules are subcentimeter and FNA evaluation is generally not indicated.
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RECOMMENDATION 25: Should TSH suppression therapy be used for benign thyroid nodules in iodine sufficient populations?
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Not recommended. Though modest responses to therapy can be detected, the potential harm outweighs benefit for most patients.
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RECOMMENDATION 26: Iodine intake in patients with benign, solid, or mostly solid nodules.
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These patients should have adequate iodine intake. If inadequate dietary intake is found or suspected, a daily supplementation of 150mcg is recommended.
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RECOMMENDATION 27 (1/2): How should one approach growing thyroid nodules that are >/= 4cm or causing symptoms.
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Surgery should be considered for growing nodules that are benign after repeat FNA if they are large (> 4cm), causing compressive or structural symptoms, or based upon clinical concern.
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RECOMMENDATION 27 (2/2): How should one monitor growing thyroid nodules that are benign after FNA bx?
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They should be regularly monitored. Most asymptomatic nodules demonstrating modest growth should be followed without intervention.
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RECOMMENDATION 28: How should one approach recurrent cystic thyroid nodules with benign cytology?
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1) They should be considered for surgical removal or percutaneous ethanol injection based on compressive symptoms or cosmetic concerns. 2) Asymptomatic cystic nodules may be followed conservatively.
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RECOMMENDATION 29: Hormone therapy to treat growing nodules with benign cytology - should it be used?
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1) There is no data to support suppressive hormone therapy to treat growing nodules with benign FNA cytology a. Suppressed TSH may cause iotrogenic thyrotoxicosis, cardiac arrhythmia, and osteoporosis b. Surgery may be considered fro growing solid nodules that are benign on repeat cytology if they are large (> 4cm), are causing compressive or structural sxs, or based on clinical concern 2) Cystic nodules recurring after aspiration may be treated with PEI or hemithyroidectomy a. PEI success rate = 85%. May have to repeat. Success achieved with an average of 2 PEI treatments. b. Complications: pain, flushing, dizziness, dysphonia 3) Consider surgery for growing solid nodules that are benign on repeat cytology if they are large (> 4cm), causing compressive or structural symptoms, or based upon clinical concern.
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Thyroid Nodules in Pregnant Women (Recommendation 30)
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1) FNA biopsy of clinically relevant nodules should be performed in euthyroid and hypothyroid pregnant women. 2) For women with suppressed TSH levels that persist beyond 16 weeks gestational age, FNA may be deferred until after pregnancy and cessation of lactation. At that time, an I123 scan may be performed to evaluate nodule function if the TSH remains suppressed. 3) Nodules enlarge slightly during pregnancy - this does not imply malignant transformation. 4) Eval of a nodule in a pregnant pt is o/w the same as for a non pregnant pt. 5) In pt with an FNA c/w DTC, delaying surgery until after delivery doesn't affect outcome. 6) Surgery during pregnancy is associated with greater risk of complications, long hospital stays, and higher costs.
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Papillary Thyroid Cancer Discovered in Early Pregnancy (Recommendation 31)
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1) PTC discovered early in pregnancy should be monitored with U/S. 2) If the PTC nodule grows substantially before 24-26 weeks gestation, or if U/S reveals cervical lymph nodes that are suspicious for metastatic disease, surgery should be considered during pregnancy. 3) If PTC remains stable by midgestation, or if it is diagnosed in the second half of pregnancy, surgery may be deferred until after delivery.
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Differentiated Thyroid Cancer
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1) Accounts for the majority of thyroid cancers 2) Papillary Thyroid Cancer accounts for 85% of all DTC 3) Follicular thyroid cancer accounts for 12% of DTC 4) Poorly Differentiated thyroid cancer accounts for < 3% of DTC 5) Stage for stage, PTC and Follicular CA have a similar prognosis
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Goals of Initial Therapy for Differentiated Thyroid Cancer
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Initial goal is to improve disease specific survival, reduce risk of persistent/recurrent disease, and permit accurate disease staging and risk stratification while minimizing treatment related morbidity and unnecessary therapy. Specific goals are to: 1) Remove the primary tumor, any contiguous spread, and lymph node mets 2) Minimize risk of recurrence and mets a. Adequate surgery most important treatment b. RAI treatment, TSH suppression, and other treatments play role in some patients 3) Facilitate post op treatment with RAI - must remove all normal thyroid tissue 4) Permit accurate staging and risk statification. 5) Permit accurate long-term surveillance for dz recurrence 6) Minimize treatment related morbidity
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[B3] What is The Role Of Preoperative Staging with Diagnostic Imaging and Laboratory Tests?
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1) Preop U/S for cervical lymph nodes (central and especially lateral neck compartments) is recommended for all patients undergoing thyroidectomy for malignant or suspicious for malignancy cytologic or molecular findings. 2) U/S guided FNA of ultrasonically suspicious lymph nods >/= 8-10mm in the smallest diameter should be performed to confirm CA if this would change management. 3) Addition of FNA-Tg washout in the evaluation of suspicious cervical lymph nodes is appropriate in some patients, but interpretation may be difficult in patients with an intact thyroid gland.
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Differentiated Thyroid Cancer Metastasis
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1) DTC (esp. Papillary) involves cervical lymph node mets in 20%-50% of patients. 2) Preop U/S identifies suspicious cervical adenopathy in 20%-31% of cases. 3) Preop U/S identifies only half of lymph nodes found at surgery.
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U/S Features Suggestive of Abnormal Metastatic Lymph Nodes
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1) Enlargement of the lymph node 2) Loss of Fatty Hilum 3) Rounded rather than oval shape 4) Hyperechogenicity 5) Cystic change 6) Calcifications 7) Peripheral vascularity Note: no single U/S feature is adequately sensitive for detection of lymph nodes with metastatic thyroid CA.
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Most Sensitive and Specific U/S features for Lymph Node Metastasis in DTC
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Sensitivity: 1) Short axis of lymph node > 5mm (96% 2) Presence of cystic areas (100%) 3) Presence of hyperechogenic punctuations representing either colloid or microcalcifications (100%) - any lymph node with Microcalcifications should be considered abnormal. 4) Peripheral vascularity (82%) Specificity 1) Peripheral vascularity (86%) 2) All of the others have specificity < 60%
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DTC Lymph Node Metastasis - Location
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1) Malignant lymph nodes more likely in levels II, IV, and VI than in level II. 2) PTC arising in the upper pole of the thyroid can have skip mets to levels II and III
