In The Name of God
Thyroid Neoplasm ORL-Head and neck Surgery 2014
Malignant Neoplasm
By age 90, virtually everyone has nodules Estimates of cancer prevalence at autopsy 4% to 36%
Why these lesions are important?
Assessment of risk of thyroid nodules requires understanding of clinical, demographic, imaging, cytopathologic, and now biomarker profiles; none of these factors alone represents a sufficient decision-making factor.
The incidence of this malignancy has been increasing over the last decade.
Advanced radiologic imaging
These scans commonly reveal small, nonpalpable thyroid nodules, which in the past would never have been identified because they were too small to detect by palpation, and too small to cause symptoms to patients
What s the problem 1. These incidental findings unnecessarily create patients with cancer with all the attendant anxiety, surveillance needs, and financial ramifications. 2. Patients are exposed to harm from what is ultimately unnecessary treatment. 3. These patients affect the validity of studies designed to understand and mitigate the risks of death or recurrence from thyroid cancer by serving to falsely improve the results of clinical trials
The chief challenge to clinicians today is deciding which nodules require workup, and how aggressively to treat them
Risk Factors
Age Gender History of radiation exposure Family history of thyroid cancer Cancer syndromes
Workup of the thyoid nodule
Laboratory Examination
TSH Hyperthyroidism(15%) Hypothyroidism(2.3%) So: TSH assessment will allow identification of people with thyroid dysfunction requiring treatment regardless of the rest of the workup.
Calcitonin Measurment There is a high false positive rate (59% or more) in some studies. The serum calcitonin cutoff levels for sporadic medullary thyroid cancer have not been agreed on.
Antithyroid peroxidase antibodies Serum thyroglobulin
Scintigraphy
Identifying hyperfunctioning nodules when a low TSH is found on initial testing Determining which nodule to sample in patients with multiple nodules (Replace with US)
Hot Cold Indeterminate
Ultrasonography
Thyroid ultrasound is the first choice of imaging studies for thyroid gland evaluation
Ultrasound has been shown to be more accurate than physical examination in detecting nodules
Nodule size Detailed characteristics Anatomic location Condition of nearby structures are all clearly delineated
Ultrasound qualities of a nodule in isolation are not diagnostic of a malignancy They do indicate which nodules are more likely to harbor malignancy Can inform decision-making about nodule selection for biopsy.
1. Microcalcifications 2. Size greater than 2 cm 3. Nodules that are entirely solid composition
Both the American Association of Clinical Endocrinologists (AACE) and the American Thyroid Association (ATA) guidelines suggest nodules as small as 5 mm might be biopsied and should be followed based on risk factors alone
Nodules greater than 4 cm, needle biopsy results were frequently false negative They eventually affect speech and swallow function due to size, surgical intervention should be considered.
Who can do it?
Defining competency is one of the central issues in all of medical education Essential equipment and the economics of clinic-based US
1) Hypoechogenicity 2) Irregular (microlobulated) margins 3) Microcalcifications 4) Anteroposterior to transverse diameter ratio greater than 1 5) Intranodular vascularity 6) Size 7) Significant growth.
Ultrasound has proven to be the most sensitive imaging modality for detecting suspicious lateral neck nodes.
The characteristic findings of shape change, loss of the normal internal structure,, and change in blood flow all contribute to the identification of metastatic nodes as small as 3 mm
Fine Needle Aspiration Biopsy
Traditional FNA Is performed by method of manual palpation The size threshold for palpating thyroid nodules is 1.5 to 2.0 cm, and up to 30% of FNA biopsies without ultrasound guidance can be nondiagnostic
The ATA guidelines suggest biopsy of those nodules preferentially that have the most worrisome ultrasound characteristics
ATA 2009 Guidelines also suggest that if there are multiple nodules and none have characteristics indicative of malignancy, it is reasonable to biopsy the largest one
USGFNA Reduced the number of inadequate samples by half In one series, USGFNA, resulting in 14% reclassification to diagnoses of malignancies limit the number of needle passes required
Needle size 1.5-inch (38-mm) length, 25-gauge needles or longer (40 50 mm) needles for lesions at greater depth. Calcified masses may be more amenable to biopsy with a finer needle, such as a 2 7 gauge. Large needle for prior failed FNA
Number of needle passes
Staining Method Papanicolaou staining: nuclear chromatin, groundglass nuclei, and nuclear grooves Giemsa stain: characteristics of cytoplasm and colloid
The Bethesda I (nondiagnostic/unsatisfact ory) Fewer than 6 groups of well-preserved, wellstained follicular cells; Poorly prepared, poorly stained, obscured follicular cells (excessively bloody specimens) cyst fluid with or without histiocytes
In inflammatory conditions of the thyroid, such as lymphocytic thyroiditis, abscess, and granulomatous thyroiditis, follicular cells may be sparse and there is no minimum requirement for adequacy for follicular cells when inflammation predominates.
The Bethesda II BENIGN THYROID LESIONS Nodular goiter: 1. hyperplastic (adenomatoid) nodule 2. colloid nodule 3. nodules in Graves disease
The Bethesda II Thyroiditis 1. Lymphocytic thyroiditis 2. Granulomatous thyroiditis 3. Acute thyroiditis
The Bethesda VI (malignant) 1. Papillary Ca 2. Medullary Ca 3. Poorly differentiated Ca 4. Anaplastic Ca 5. lymphoma 6. Various metastatic tumor
INDETERMINATE THYROID LESIONS
Cases diagnosed as atypical, follicular neoplasm, and suspicious for malignancy were lumped together in one category
The Bethesda III Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance The architectural and/or cytologic atypia is not sufficient to be classified as suspicious for follicular neoplasm, SFM, or malignant but is more than confidently diagnosed as benign
The Bethesda III 1. Clinicians should be aware that this is a category of last resort. 2. pathologists make significant efforts not to use this designation indiscriminately. 3. The frequency of AUS/FLUS interpretation should be approximately 7% of all thyroid FNA interpretations.
The Bethesda IV Follicular neoplasm / Suspicious for Follicular Neoplasm 1. The hallmark of this category is the presence of an abnormal architecture (architectural atypia), usually in a highly cellular specimen 2. FNHCT/SFNHTC should be used when at least 75% of the cells show Hurthle cell phenotype
Bethesda V Suspicious for Malignancy when some features of malignancy raise a strong suspicion for malignancy but the findings are not sufficient for a definitive diagnosis either qualitatively or quantitatively 1. uncommon variants of the respective malignancies 2. overlapping features with benign conditions (lymphocytic thyroiditis)suboptimal sampling.
Needle biopsy results that are read as benign or malignant provide clear data on which to make clinical decisions. Up to nearly a third of needle biopsies will be returned as cytologically indeterminate.
Molecular Markers
Molecular testing of needle biopsy specimens read as malignant will not add useful information to the therapeutic decisionmaking process
BRAF RAS RET/PTC
Overall, tumor pathologic features continue to be most indicative of prognosis and therefore most clinically useful.
Treatment Modalities
Surgery Lobectomy ± Isthmectomy Total thyroidectomy Vs less than total Neck dissection
Surgical Technique Conventional thyroidectomy Minimally invasive cervical approach Remote access approaches
These alternative approaches have been applied to small, low-risk, well-differentiated thyroid cancers
Difficult or even unsafe in instances of large goiters, substernal or retropharyngeal extension, or thyroiditis. Furthermore, patients with thyroid malignancies need to be carefully considered to provide the most oncologically appropriate surgery for their disease.
The preoperative detection of lymph node involvement by either clinical examination or imaging can significantly clarify the goal of neck management and make clear the distinction between a prophylactic and therapeutic neck dissection.
Central Lymph Node Compartment Include the prelaryngeal (Delphian), pretracheal, and paratracheal nodes. An adequate unilateral central neck dissection, as defined by the ATA, should include the prelaryngeal, pretracheal, and the ipsilateral paratracheal nodal group. If performed with therapeutic intent, it is recommended that the dissection be extended to include bilateral paratracheal nodal groups.
Lateral compartment Meta-analysis data: high prevalence of multilevel disease: II 53%, III71%, IV 66% V 25% The ATA has further reviewed the lateral neck dissection and recommends a therapeutic dissection of levels IIa, III, IV, and Vb when suspicious
Prophylactic neck dissection Current guidelines recommend considering a prophylactic central neck dissection if other factors in patient presentation prompt a total thyroidectomy. ATA, which broadly suggest considering prophylactic central neck dissection, especially inpatients with advanced primary tumors larger than 4 cm
Consider a prophylactic central compartment neck dissection in papillary thyroid carcinomas that are either large tumors (>4 cm) or those with extrathyroidal extension
Routine prophylactic central neck dissections for follicular carcinomas are therefore not recommended
Hurthle cell carcinoma Literature and recommendations support a therapeutic central and/ or lateral compartment neck dissection for clinically involved nodes in Hurthle cell carcinoma and suggest considering a prophylactic central compartment neck dissection if a TT is prompted by other factors
Medullary Ca Routine central compartment neck dissection is recommended for patients with sporadic medullary thyroid cancer greater than 1 cm or patients with bilateral thyroid disease. Lateral neck dissection may be reserved for patients with clinically evident disease on preoperative examination or imaging. patients with even limited central involvement (1 3 positive nodes) have a high rate of lateral compartment disease. Thus, some clinicians have advocated for prophylactic lateral neck dissection when medullary carcinoma has spread to the central lymph node compartment.
Surgical technique Central compartment Dissection begins at the innominate artery below and ends at the hyoid bone above. The lateral extent of the central compartment dissection is the medial border of the carotid sheath Once an indication for central compartment dissection has been confirmed, the surgeon should be as comprehensive as possible in removing nodes Preserve the anatomic integrity Minimize trauma to both the recurrent laryngeal nerves and vascularized parathyroid
Modified Radical Neck Dissection (Levels II, III, IV, and V) Direct invasion or true nodal fixation is uncommon for metastases of DTC Nodal berry-picking procedures are associated with unacceptably high levels of disease recurrence in the neck and should not be performed.
Surgical Notes Careful attention must be paid to the route of common metastatic spread: along the superior thyroid artery and the transverse cervical artery. Small nodes can be missed if the surgeon is rushed or not systematic in the dissection of this crucial area.
POSTOPERATIVE CARE AND MANAGEMENT
Hypoparathyroidism and Hypocalcemia Postoperative period strongly predict glandular function. Those in a low but detectable range predict a higher probability of transient or permanent hypocalcemia. Moreover, undetectable ipth levels are strongly correlated with hypocalcemia requiring intravenous infusion of calcium gluconate in the postoperative period.
Empiric oral supplementation with elemental calcium and vitamin D is generally warranted after paratracheal and mediastinal lymph node dissection. Intravenous calcium gluconate is reserved for patients with symptomatic hypocalcemia manifest by perioral numbness or tingling in the fingers or toes.
An infusion can be delivered by adding 10 ampoules of calcium gluconate to a 500-mL of normal saline and beginning at 30 ml/h, titrating up as needed to control symptoms.
Recurrent Laryngeal Nerve Injury The absence of voice disturbance does not guarantee normal nerve function; vocal cord paralysis (identified by laryngoscopy) is more sensitive at identifying recurrent laryngeal nerve defects caused by invasive thyroid malignancy.
Spinal Accessory Nerve Rehabilitation Even after preservation of the spinal accessory nerve, circumferential dissection can lead to devascularization and subsequent fibrosis. Therefore, early, if not immediate, postoperative rehabilitation is mandatory especially when level II-b is dissected.
Other Malignancies Anaplastic Ca Lymphoma Metastatic Ca
I-Ablation
Postoperative RT
CLOSING THOUGHTS ABOUT THYROID NODULE EVALUATION
Risk of Death for the Patient Found to Have a Thyroid Cancer
It has often been said that well-differentiated thyroid carcinoma is a disease of morbidity and not mortality
The point of evaluating a patient with a thyroid nodule is to determine whether a cancer is present. It is important to remember that, although everyone fears cancer, the outlook for patients diagnosed with papillary thyroid cancer, which is about 88% of thyroid cancers diagnosed in the United States, is excellent.
The 20-year survival for papillary thyroid cancer of any size confined to the thyroid gland at the time of diagnosis is 99%. For some patients, their competing risk of death from their other illnesses will be much greater, making workup of a thyroid nodule of lower utility to them. At a rate of 0.5 per 100,000 people, the mortality due to thyroid cancer is about the same as it is for tuberculosis that is, very rare.
In recent years, selected small cancers have been observed rather than operated on immediately Among those that grow or spread, surgical salvage has been successful, which means that delaying treatment will not necessarily present a problem for patients. These facts should be part of the mental algorithm used when talking with patients about the decision to evaluate a thyroid nodule.
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