Assessment of thyroid lesions (general)

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Assessment of thyroid lesions is commonly encountered in radiological practice.

Thyroid mass

hyperplastic/colloid nodule ~~/ nodular~~/nodular hyperplasia: 85%
adenoma
- follicular: 5%
- others: rare
carcinoma
- papillary: 60-80% of carcinomas
- follicular: 10-20%
- medullary: 5%
- anaplastic: 1-2%
- thyroid lymphoma: 1%
- metastases to the thyroid: 1%
others
- fat ~~containing~~-containing thyroid lesions
  - adenolipoma of the thyroid gland
  - liposarcoma of the thyroid gland

Risk factors for malignancy

young
male
solitary
cold on thyroid scan
past history of radiotherapy

The first three risk factors are really a reflection that elderly women with multiple benign thyroid nodules are very common.

Radiographic features

Ultrasound

taller-than-wide in axial/transverse dimension, microcalcifications, local invasiveness, microlobulated contour, and hypoechogenicity are suspicious features
size criteria are controversial and continuously evolving
cervical lymphadenopathy is a feature
for detailed assessment, see: assessment of thyroid lesions (ultrasound)

Nuclear medicine

A single 'cold' nodule has a 10% chance of being malignant. A single 'hot' nodule has <1% chance of being malignant.

Treatment and prognosis

Indications for FNA

Each grading system provides recommendations for when FNA is indicated (see snippet for individual systems).

Both appearance and size are factors to consider.

The criteria developed by the American Thyroid Association (2015) ⁶ are often used in clinical practice. See: ATA guidelines for assessment of thyroid nodules.

The ACR TI-RADS system recommends FNA for TR3 lesions >25 mm, TR4 lesions >15 mm and TR5 lesions >10 mm ¹¹.

The BTA U classification recommends ~~FSA~~FNA for any non-benign lesion (i.e. U3, U4 or U5) ¹².

Additional recommendations for FNA by the American Association of Clinical Endocrinologists ⁴:

FNA recommended for nodules <10 mm whenever clinical information or ultrasound features raises suspicion about the presence of a malignancy

Management of FNA results

benign: clinical and imaging follow-up
follicular neoplasm
- require excisional biopsy because of overlap between
  - hyperplastic nodule
  - follicular adenoma
  - follicular carcinoma
  - follicular variant of papillary carcinoma
atypia of uncertain significance / follicular lesion of uncertain significance (AUS/FLUS)
- 3-6%
- repeat FNA
  - two samples obtained at second biopsy
  - if AUS/FLUS again (~20%) on the first sample, then the risk of malignancy is 5-15% ¹⁰
  - the second sample may be sent for gene sequencing, if available (gene expression classifier)
    - if benign, then normal clinical and imaging follow-up
    - if suspicious, 50% risk of malignancy
malignant: partial or total thyroidectomy with lymph node exploration

Staging

see: thyroid cancer staging

~~-<li>hyperplastic / <a href="/articles/colloid-nodule-thyroid-1">colloid nodule</a> / nodular hyperplasia: 85%</li>~~
+<li>hyperplastic/<a href="/articles/colloid-nodule-thyroid-1">colloid nodule</a>/nodular hyperplasia: 85%</li>
~~-<a href="/articles/fat-containing-thyroid-lesions">fat containing thyroid lesions</a><ul>~~
+<a href="/articles/fat-containing-thyroid-lesions">fat-containing thyroid lesions</a><ul>
~~-<li>past history of radiotherapy</li>~~
+<li>past history of <a title="Radiotherapy" href="/articles/radiation-therapy">radiotherapy</a>
+</li>
-</ul><h5>Nuclear medicine</h5><p>A single 'cold' nodule has a 10% chance of being malignant. A single 'hot' nodule has <1% chance of being malignant.</p><h4>Treatment and prognosis</h4><h5>Indications for FNA</h5><p>Each grading system provides recommendations for when FNA is indicated (see snippet for individual systems).</p><p>Both appearance and size are factors to consider.</p><p>The criteria developed by the <strong>American Thyroid Association</strong> (2015) <sup>6</sup> are often used in clinical practice. See: <a href="/articles/ata-guidelines-for-assessment-of-thyroid-nodules">ATA guidelines for assessment of thyroid nodules</a>.</p><p>The <a title="ACR Thyroid Imaging Reporting and Data System (ACR TI-RADS)" href="/articles/acr-thyroid-imaging-reporting-and-data-system-acr-ti-rads">ACR TI-RADS</a> system recommends FNA for TR3 lesions >25 mm, TR4 lesions >15 mm and TR5 lesions >10 mm <sup>11</sup>.</p><p>The <a title='BTA ultrasound "U" classification of thyroid nodules' href="/articles/bta-ultrasound-u-classification-of-thyroid-nodules">BTA U classification</a> recommends FSA for any non-benign lesion (i.e. U3, U4 or U5) <sup>12</sup>.</p><p>Additional recommendations for FNA by the American Association of Clinical Endocrinologists <sup>4</sup>:</p><ul><li>FNA recommended for nodules <10 mm whenever clinical information or ultrasound features raises suspicion about the presence of a malignancy</li></ul><h5>Management of FNA results</h5><ul>
+</ul><h5>Nuclear medicine</h5><p>A single 'cold' nodule has a 10% chance of being malignant. A single 'hot' nodule has <1% chance of being malignant.</p><h4>Treatment and prognosis</h4><h5>Indications for FNA</h5><p>Each grading system provides recommendations for when FNA is indicated (see snippet for individual systems).</p><p>Both appearance and size are factors to consider.</p><p>The criteria developed by the <strong>American Thyroid Association</strong> (2015) <sup>6</sup> are often used in clinical practice. See: <a href="/articles/ata-guidelines-for-assessment-of-thyroid-nodules">ATA guidelines for assessment of thyroid nodules</a>.</p><p>The <a href="/articles/acr-thyroid-imaging-reporting-and-data-system-acr-ti-rads">ACR TI-RADS</a> system recommends FNA for TR3 lesions >25 mm, TR4 lesions >15 mm and TR5 lesions >10 mm <sup>11</sup>.</p><p>The <a href="/articles/bta-ultrasound-u-classification-of-thyroid-nodules">BTA U classification</a> recommends FNA for any non-benign lesion (i.e. U3, U4 or U5) <sup>12</sup>.</p><p>Additional recommendations for FNA by the American Association of Clinical Endocrinologists <sup>4</sup>:</p><ul><li>FNA recommended for nodules <10 mm whenever clinical information or ultrasound features raises suspicion about the presence of a malignancy</li></ul><h5>Management of FNA results</h5><ul>

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