31th European Congress of Pathology, Nice, France, 7 September - 11 November 2019, vol.31, no.1, pp.3-9
Background & Objectives: Molecular testing has been proposed to
refine the assessment of cancer risk in thyroid nodules with indeterminate
cytology. The aim of this study is to compare the genotypic alterations for
BRAF, NRAS, and KRAS mutations of FNA samples in indeterminate
and malignant category with subsequent histology of surgical specimens
in our routine practices.
Methods: We reviewed 150 cases diagnosed as atypical by ultrasoundguided
thyroid FNA cytology on the basis of the Bethesda system who
had undergone molecular testing. FNA samples were tested for BRAF,
NRAS, and KRAS point mutations by real-time polymerase chain reaction
(RT-PCR). Out of these 150 cases, 71 had undergone surgical procedure
and histopathology results,were compared with both cytology and
molecular status. According to the final pathological results, we divided
the cases, as benign and malign groups.
Results: According to the Bethesda System the 71 cases were distributed as
13 AUS/FLUS, 24 FN/SFN, 13 SM, and 21 malign categories. Of the 71
cases of atypical cytology, 48 cases (67.6 %) were diagnosed as malignant,
and 23 cases (32.4 %) were diagnosed as benign at surgical specimens. In
71 nodules, 37 samples (52.1%) had point mutations. Overall positive
predictive value of cytology evaluation was 67.6 % and overall positive
predictive value of cytology and molecular testing was 89.2 % (p=0.004).
Conclusion: The addition of molecular testing to FNA cytology may
increase the positive predictive value of cytology.