Nodule size is an independent predictor of malignancy in mutation-negative nodules with follicular lesion of undetermined significance cytology

Rohtesh S. Mehta, Sally E. Carty, N. Paul Ohori, Steven P. Hodak, Christopher Coyne, Shane O. Lebeau, Mitchell E. Tublin, Michael T. Stang, Jonas T. Johnson, Kelly L. McCoy, Marina N. Nikiforova, Yuri E. Nikiforov, Linwah Yip

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37 Scopus citations

Abstract

Background In thyroid nodule fine-needle aspiration (FNA) cytology, the atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) category has a 5-15% malignancy risk that increases to 85-99% when mutation testing for BRAF, RAS, RET/PTC, or PAX8/PPARγ is positive. However, negative testing does not exclude malignancy. The study objective was to identify clinical and imaging features that predict cancer in mutation-negative AUS/FLUS thyroid nodules. Methods All patients were reviewed (April 2007 to April 2009) who had AUS/FLUS cytology, negative prospective molecular testing of FNA, and histopathology. Results Of the 230 nodules, 12 (5.2%) were malignant in 11 of 190 patients, and known clinical risk factors for thyroid cancer did not predict malignancy. On preoperative imaging, ≥1 suspicious ultrasound feature was identified in 33% of nodules and occurred regardless of histology (P =.23). Malignant mutation-negative AUS/FLUS nodules were larger than benign nodules (mean maximum diameter, 33.6 vs 24.0 mm; P =.007). On multivariate analysis, nodule size remained an independent predictor of malignancy (odds ratio, 1.043; P =.018). We observed no malignancies in 88 mutation-negative AUS/FLUS nodules <18.5 mm. Conclusion Size is an independent predictor of malignancy in mutation-negative AUS/FLUS nodules and the risk increased 4.3% with every millimeter increase in nodule size. Selected patients with small, mutation-negative AUS/FLUS thyroid nodules may be managed with ultrasound surveillance in lieu of thyroidectomy.

Original languageEnglish (US)
Pages (from-to)730-738
Number of pages9
JournalSurgery (United States)
Volume154
Issue number4
DOIs
StatePublished - Oct 2013
Externally publishedYes

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