AUTHOR: Peter J. Mazzaglia, MD
An abnormal growth of thyroid tissue detected on either physical examination or radiographic imaging, and ultimately confirmed by thyroid ultrasound.
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Physical exam is helpful if there are overt signs of hyperthyroidism or malignancy, but these are uncommon. Diagnosis usually relies on laboratory tests, radiographic studies, and cytology.1
Figure 1 Workup of a thyroid nodule.
AUS, Atypia of undetermined significance; FLUS, follicular lesion of undetermined significance; FN, follicular neoplasm; FNA, fine-needle aspiration biopsy; SFN, suspicious for follicular neoplasm; TSH, thyroid-stimulating hormone.
Modified from Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.
TABLE 2 Bethesda Classification System for Thyroid Nodules
Diagnostic Category Bethesda Classification | Risk of Malignancy | Action |
---|---|---|
I Nondiagnostic | 1-4 | Repeat biopsy after 4 wk; if very low risk, follow with ultrasound |
II Benign | 1-3 | 1-yr follow-up ultrasound |
III Atypia (follicular lesion) of undetermined significance (AUS/FLUS) | 5-15 | Repeat biopsy in 3 mo; consider genetic testing |
IV Follicular neoplasm | 15-30 | Thyroid lobectomy; consider genetic testing if nodule appears low risk or patient wishes to avoid surgery |
V Suspicious | 60-75 | Thyroid lobectomy or total thyroidectomy |
VI Malignant | 97-99 | Thyroid lobectomy or total thyroidectomy |
Adapted from Cibas ES, Ali SZ: The Bethesda system for reporting thyroid cytopathology, Am J Clin Pathol 132:658-665, 2009.
TABLE 1 American College of Radiology Thyroid Nodule Scoring System: TI-RADS
Scoring and Classification | Recommendations | ||
---|---|---|---|
TR1: 0 points | TR1: No FNA required (0.3% risk) | ||
TR2: 2 points | TR2: No FNA required (1.5% risk) | ||
TR3: 3 points | TR3: ≥1.5 cm follow-up at 1, 3, 5 yr, ≥2.5 cm FNA (4.8% risk) | ||
TR4: 4-6 points | TR4: ≥1.0 cm follow-up at 1, 2, 3, 5 yr ≥1.5 cm FNA (9.1% risk) | ||
TR5: ≥7 points | TR5: ≥0.5 cm follow-up each year, ≥1.0 cm FNA (35% risk) |
ACR TI-RADS is a reporting system for thyroid nodules on ultrasound proposed by the American College of Radiology (ACR) and is based on composition, echogenicity, shape, margin, and echogenic foci.
From Tessler FN et al: ACR Thyroid Imaging, Reporting and Data System (TI-RADS): white paper of the ACR TI-RADS committee, J Am Coll Radiol 14:587-595, 2017.
TABLE 3 Ultrasound Features Suggestive of Benign and Malignant Thyroid Nodules
Benign | Suspicious for Malignancy | |
---|---|---|
Nodule characteristics | ||
Nodule margin | ||
Calcification | ||
Metastatic spread |
From Tessler FN et al: ACR Thyroid Imaging, Reporting and Data System [TI-RADS]: white paper of the ACR TI-RADS Committee, J Am Coll Radiol 14:587-595, 2017.
This scan is consistent with a toxic or hyperfunctioning nodule.
From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.
Figure E4 Conventional and color flow Doppler ultrasonography.
A, Benign lesion. Sonogram shows well-defined, oval, hyperechoic nodule with perinodular and slight intranodular blood flow. B, Malignant lesion. Sonogram shows a nodule with inhomogeneous hypoechoic aspect, microcalcifications, irregular borders, and invasion of the thyroid capsule (arrows).
From Melmed S et al: Williams textbook of endocrinology, ed 12, Philadelphia, 2011, Elsevier.
Variable with results of FNA biopsy. Once patients have had a benign biopsy and a 1-yr follow-up ultrasound shows no significant growth, they do not require annual thyroid ultrasound exams. They can be followed with an annual neck exam. If growth is detected or symptoms develop, repeat ultrasound is indicated.
Thyroid Nodule (Patient Information)
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