Thyroid Nodules¶
Terra Swanson
Background¶
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~50% of adults will have a thyroid nodule on ultrasound
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Benign: goiter, cyst, inflammatory, Hashimoto’s, follicular adenoma (microadenoma)
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Malignant: follicular, papillary, medullary, anaplastic, metastatic, thyroid lymphoma
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Risk factors for malignancy: age <30, head or neck radiation, family history of thyroid cancer
Evaluation¶
- TSH, Free T4, Thyroid U/S
Management¶
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If Low TSH: Likely a hyperfunctioning "hot" nodule (benign in 95% of cases)
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Order Iodine-123 or technetium-99m thyroid scan
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If hyperfunctioning → measure T3/free T4 if ↑, treat for hyperthyroidism
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If non-functioning → proceed as if TSH were normal
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Normal or elevated TSH:
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FNA indicated based on U/S findings listed below (determined by TI-RADS system)
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Nodules >1 cm that have high- or intermediate-suspicion pattern
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Nodules >1.5 cm that have low-suspicion pattern
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Nodules >2 cm that have very-low-suspicion pattern
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FNA cytology determines the plan of action:
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Benign → periodic US monitoring at 12-24 months, then at increasing intervals
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Indeterminate → repeat FNA in 3-12 months
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Malignant → surgical referral
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Nodules that do not meet FNA criteria, US findings determine the timing for follow-up imaging:
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High suspicion: 6-12 months
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Low to intermediate suspicion: 12-24 months
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Nodules >1 cm with very ↓ suspicion OR pure cyst: >24 months if at all
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Nodules <1 cm with very ↓ suspicion OR pure cyst: no further imaging necessary