Assessment of thyroid lesions (general)

Dr Matt A. Morgan and Dr Jeremy Jones et al.

Assessment of thyroid lesions is commonly encountered in radiological practice.

Thyroid mass breakdown
Risk factors of a nodule being malignant
  • 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

  • taller-than-wide in axial/transverse dimension, microcalcifications, local invasiveness, microlobulated contour, and hypoechogenicity are suspicious features
  • size criteria are controversial and continously 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

The criteria developed by the American Thyroid Association (2015) 11 are often used in clinical practice. See: ATA guidelines for assessment of thyroid nodules.

Indications for FNA according to Society of Radiologists in Ultrasound (2008) 4

  • nodule ≥1.0 cm at the largest diameter if microcalcifications are present
  • nodule ≥1.5 cm if the nodule is solid or if there are coarse calcifications within the nodule

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
  • 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

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