Refining the Management of Bethesda III Thyroid Nodules by Combining Nuclear Atypia with Sonographic Suspicion.

OBJECTIVE

The risk of malignancy (ROM) in thyroid nodules with Bethesda III cytology ranges from 6% to 30%. Further stratification may aide the decision for diagnostic hemithyroidectomy.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary general hospital.

METHODS

Bethesda III thyroid nodules consecutively resected between 2010 and 2016 are reviewed. Sonographic images are matched to the pathologic diagnoses and exported. Blinded to the diagnosis, 2 to 3 radiologists reached a consensus on the ACR-TIRADS, EU-TIRADS, and ATA classification of the nodules. A head and neck pathologist reviewed the cytology for nuclear atypia. Univariate and multivariate analyses are performed.

RESULTS

Out of a total of 243 nodules, 63 (26%) are malignant and 3 (1.2%) are NIFTP. Nuclear atypia, hypoechogenicity, intermediate and high-risk categories in ACR-TIRADS, EU-TIRADS, or ATA are significantly associated with malignancy (including NIFTP) in both univariate and multivariate analysis (P < .001-.028). The area-under-the-receiver-operator-curve of the diagnostic model incorporating sex, nuclear atypia, and sonographic suspicion is 0.714, 0.695, 0.711, and 0.699, respectively, when sonographic suspicion is defined as hypoechogenicity, TR4/5, EU-TIRADS intermediate/high-risk, or ATA moderate/high suspicion. In TR5, EU-TIRADS or ATA high-risk nodules or nodules with marked hypoechogenicity/punctate echogenic foci/irregular margins, nuclear atypia significantly increases the ROM from 6.3%-9.7% to 59.4%-75.0%. Majority of the cancers diagnosed by nuclear atypia and sonographic suspicion are papillary carcinomas.

CONCLUSION

Diagnostic hemithyroidectomy is recommended in nodules with both AUS-nuclear atypia and high sonographic suspicion. Improved identification of follicular-patterned thyroid carcinomas is required to better manage the other Bethesda III nodules.