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Updated: Oct 15, 2025
Substernal Thyroid Biopsy Using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration
Published on: November 10, 2014
Feasibility and performance of the Idylla™ NRAS/BRAF cartridge mutation assay on thyroid liquid-based fine-needle
Maud Hamadou1, Jonathan Lopez1,2,3, Nazim Benzerdjeb3,4
1Département de Biochimie et de Biologie Moléculaire, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre Bénite, France.
Background:
Thyroid nodules with indeterminate cytology represent up to 30% of cases. Molecular testing is now highly recommended to improve management. This study aimed to evaluate the use of the Idylla™ NRAS/BRAF mutation test, a rapid and automated polymerase chain reaction (PCR) assay validated for fixed paraffin-embedded use, on residual thyroid liquid-based fine-needle aspiration (LB-FNA).
Methods:
Concordance between mutations detected by the Idylla™ assay and the gold-standard qPCR was assessed by splitting in two aliquots 31 BRAF or RAS mutated and 5 non-mutated LB-FNA samples. Samples were obtained either from simulated FNA after thyroidectomy or from FNA obtained during routine care. A third aliquot was used to assess the limit of detection of Idylla™ for five mutated samples.
Results:
The Idylla™ assay showed a sensitivity of 97% and a specificity of 83% as results were concordant for 34 out of 36 samples. One discordant sample concerned a BRAF p.K601E-mutation which is not detected by the Idylla™ cartridge. The other showed a false-positive NRAS p.A146T detection and a weak BRAF p.V600E detection. The limit of detection of the Idylla™ assay was not reached by the dilution assay.
Conclusion:
Idylla™ NRAS/BRAF mutation testing can be performed on residual thyroid LB-FNA, using low DNA quantity input, thus not requiring a dedicated sample. The Idylla™ NRAS/BRAF assay offers a quick and easy first step for analyzing the main molecular alterations in indeterminate thyroid nodules, hence improving diagnostic management.
