This article is more than 5 years old. Information may no longer be current.
Ultrasonography features may help distinguish thyroid nodules
Click Here to Manage Email Alerts
Ultrasonography features for thyroid nodules may help differentiate nodules that are atypia of undetermined significance or follicular lesion of undetermined significance, study data indicate.
Soo Yeon Hahn, MD, of the department of radiology and center for imaging science at Samsung Medical Center, Sungkyunkwan University School of Medicine in Korea, and colleagues assessed 327 thyroid nodules identified on ultrasound as atypia of undetermined significance (AUS; n = 253) or follicular lesion of undetermined significance (FLUS; n = 74) that were subsequently removed surgically or followed with ultrasound for at least 12 months between April 2011 and April 2012 at Sungkyunkwan University School of Medicine. Researchers sought to determine whether ultrasonography contributes to the differentiation of AUS from FLUS and may suggest categories of malignancy within the Bethesda system for reporting thyroid cytopathology category III.
The risk for malignancy in category III was 41.3% for all nodules; the risk was greater in the AUS group (51%) compared with the FLUS group (8.1%; P < .001). Papillary thyroid carcinoma was more common in the AUS group (97.7%) compared with the FLUS group (66.7%; P = .004). The FLUS group had a higher incidence of follicular thyroid carcinoma (33.3%) compared with the AUS group (1.6%; P = .004); however, benign results were more common on the FLUS group (91.9%) compared with the AUS group (49%; P < .001).
There were 211 samples that were adequate for BRAF mutation analysis; 88.6% were classified as AUS and 47.6% of those had BRAF mutations.
The AUS group had an ultrasonography diagnosis suggestive for malignancy more frequently than the FLUS group (66% vs. 12.2%; P < .001). Differences were found between the groups for echogenicity, margin, calcifications and shape (P < .05 for all).
The AUS group was more likely to have parameters of smaller nodule size, hypoechogenicity, marked hypoechogenicity, noncircumscribed margin, microcalcification, taller-than-wide shape and an ultrasound diagnosis suggestive for malignancy compared with the FLUS group (P < .05 for all). Independent predictors to differentiate between AUS and FLUS were margin (P < .001), shape (P = .014) and ultrasound diagnosis suggestive for malignancy (P = .001).
“Margin, shape and an [ultrasonography] diagnosis suggestive for malignancy (a nodule which had at least one malignant [ultrasonography] feature as marked hypoechogenicity, noncircumscribed margin, microcalcifications, and taller-than-wide shape) can be predictive factors for differentiating between AUS and FLUS,” the researchers wrote. “Therefore, Bethesda system category III subcategorization into AUS and FLUS can be supported by [ultrasound] features. In Bethesda III nodules, [ultrasonography] features may further help predicting a malignant histology.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
Perspective
Back to Top
Trevor E. Angell, MD
This study evaluates the thyroid cancer rate, sonographic features and BRAF mutation status of nodules with a cytologic finding of atypia of undetermined significance (AUS) compared with those labeled follicular lesion of undetermined significance (FLUS), which are two subcategories of the Bethesda III classification of thyroid cytology. The study’s strengths are the large sample size, use of Bethesda categorization, and comprehensive description of clinically relevant sonographic features used to characterize thyroid nodules.
The results largely reproduce patterns found in previous studies. The cytologic atypia in the AUS category has been recognized to have higher risk for malignancy than the architectural atypia described by the FLUS designation (VanderLaan PA Am J Clin Pathol. 2011; doi:10.1309/AJCP4P2GCCDNHFMY). Given this, it is not surprising that sonographic features and BRAF mutations more closely associated with thyroid cancer are similarly associated with the AUS category.
The article suggests that sonographic features can differentiate AUS from FLUS nodules. The clinical validity of this approach remains uncertain since the study evaluated nodules after the cytologic diagnosis of AUS or FLUS had been rendered and does not evaluate whether sonographic features predict AUS or FLUS cytology in all nodules. The key point from these data is that nodules with sonographic features suggestive of malignancy may need further evaluation even when cytology is lower risk (eg, FLUS). This supports the recent recommendations from the American Thyroid Association that nodules categorized as sonographically “high risk” should undergo a repeat fine-needle aspiration within 12 months, even if initial cytology is benign (Haugen BR Thyroid. 2016;doi:10.1089/thy.2015.0020).
Click Here to Manage Email Alerts