Contribution of molecular testing to thyroid fine‐needle aspiration cytology of “follicular lesion of undetermined significance/atypia of undetermined significance”

Abstract

By cytomorphology alone, follicular lesion of undetermined significance/atypia of undetermined significance specimens represent cases that are intermediate in risk between the benign and "suspicious for follicular neoplasm" categories. Although not all papillary carcinoma cases are detected by molecular testing, a positive molecular test result is very helpful in refining follicular lesion of undetermined significance/atypia of undetermined significance cases into high-risk and low-risk categories.

The atypia of undetermined significance/follicular lesion of undetermined significance:malignant ratio

“…In fact, most initial experiences with AUS have reported AUS rates > 7%, often substantially so. 3,[6][7][8][9][10][11][12]14 Our goal in undertaking this study was to identify performance measures within TBS that would guide reasonable laboratory practice, particularly with regard to use of the AUS category. We sought to establish whether a performance measure similar to the ASCUS:SIL ratio in cervical/vaginal cytology might be identifiable within thyroid FNA, although clearly recognizing that such a parameter will have limitations much as the ASCUS:SIL ratio does.…”

“…The heterogeneity of this low-risk category inevitably means that there will be differences in its utilization with significant variability in AUS rates noted among individual practitioners as well as between laboratories. [2][3][4][5][6][7][8][9][10][11][12][13][14] Indeed, TBS only recommends a broad use range for each diagnostic category. 1 To promote uniform practice among laboratories and cytopathologists and encourage quality improvement, it is desirable to have performance measures associated with TBS, especially with regard to the AUS category.…”

“…15 The only such recommendation that accompanied TBS for thyroid cytopathology was that the AUS rate not exceed 7% 1 ; however, this proposal lacked a robust evidentiary basis and has proved to be unrealistic for many laboratories publishing their initial experiences with TBS. [2][3][4][5][6][7][8][9][10][11][12][13][14] In this study, we review the initial published experiences with AUS and TBS in conjunction with our own laboratory experiences, with the goal of identifying evidencebased performance measures that will have usefulness in measuring individual and laboratory practices. In so doing, we hope to provide a basis for quality improvement in the reporting of thyroid aspirates within TBS framework.…”

An update on molecular biology of thyroid cancers

“…Ohori et al suggested a panel of biomarkers including BRAF-RAS gene mutations and RET/PTC-PAX8-PPAR␥ gene translocations to optimize FNAB results [211]. This panel includes some of the most frequent and specific molecular markers identified to date for thyroid cancer and may be used in routine practice.…”

“…Thus, the patient may be referred to surgery without repeated FNAB. Conversely, the risk of cancer is about 0-7% in thyroid nodules those are negative for all these mutations [196,211]. In this lowest risk group, follow-up is sufficient without the necessity of surgical intervention.…”