Sonographic pattern | US features | Estimated risk of malignancy, % | FNA size cutoff (largest dimension) |
---|---|---|---|
High suspicion | Solid hypoechoic nodule or solid hypoechoic component of a partially cystic nodule with one or more of the following features: irregular margins (infiltrative, microlobulated), microcalcifications, taller than wide shape, rim calcifications with small extrusive soft tissue component, evidence of ETE | >70–90 | Recommend FNA at ≥1 cm |
Intermediate suspicion | Hypoechoic solid nodule with smooth margins without microcalcifications, ETE, or taller than wide shape | 10–20 | Recommend FNA at ≥1 cm |
Low suspicion | Isoechoic or hyperechoic solid nodule, or partially cystic nodule with eccentric solid areas, without microcalcification, irregular margin or ETE, or taller than wide shape. | 5–10 | Recommend FNA at ≥1.5 cm |
Very low suspicion | Spongiform or partially cystic nodules without any of the sonographic features described in low, intermediate, or high suspicion patterns. | <3 | Consider FNA at ≥2 cm Observation without FNA is also a reasonable option |
Benign | Purely cystic nodules (no solid component) | <1 | No biopsy |