Thyroid Nodules
8
Table 1. Sonographic Patterns, Estimated Risk of Malignancy
and FNA Guidance for Thyroid Nodules
Sonographic
Pattern US features
Estimated risk
of malignancy
Consider
biopsy
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
so tissue component, evidence of
extrathyroidal extension
>70-90%
a
Recommend
FNA at >1 cm
Intermediate
suspicion
Hypoechoic solid nodule
with smooth margins without
microcalcifications, extrathyroidal
extension, 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 extrathyroidal extension, 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
b
Note: US-guided FNA is recommended for cervical lymph nodes that are sonographically suspicious
for thyroid cancer.
a
e estimate is derived from high volume centers, the overall risk of malignancy may be lower given
the interobserver variability in sonography.
b
Aspiration of the cyst may be considered for symptomatic or cosmetic drainage.
