Ultrasound indications for FNAC

U/S can be used to risk-stratify using the Thyroid Imaging Reporting and Data System (TI-RADS) (http://tiradscalculator.com/)

Solid nodule

  • With suspicious sonographic  features                                     >1.0 cm
  • Without suspicious sonographic features                               >1.5 cm

Mixed cystic-solid nodule

  • With suspicious sonographic  features: hypoechoic,
    microcalcifications, infiltrative margins, taller
    than wide in transverse plane                                               Solid component >1.0 cm
  • Without suspicious sonographic features: Spongiform
    nodules, isoechoic of hyperechoic solid nodules, mixed
    solid-cystic nodules without above suspicious features     Solid component >1.5 cm

Spongiform nodule (multiple microcystic components
in >50% of volume of nodule                                                       >2.0 cm

Suspicious cervical lymph node: FNAC of node +/- thyroid nodule

If FNAC not indicated, then repeat US after 6-12 months; if stable for 1-2yrs, then consider US at 3-5 yearly intervals

Above criteria are general guidelines: With high risk clinical features, evaluation of smaller nodules may be indicated based on clinical concerns e.g. prior thyroid cancer, radiation exposure, 1st degree relative with thyroid cancer of MEN2, FDG avid on PET scan, thyroid cancer associated history e.g. familial adenomatous polyposis, Carney complex, Cowden syndrome

Index: Clinical Practice Guidelines for Thyroid