Real-Time Evaluation of Thyroid Cytology Using New Digital Microscopy Allows for Sample Adequacy Assessment, Morphological Classification, and Supports Molecular Analysis

SIMPLE SUMMARY: The detection of thyroid nodules is increasing worldwide. Fine needle aspiration biopsy (FNA) is used to differentiate benign and malignant nodules and to address patient management; about 30% of patients receive indeterminate or inadequate cytological report. This clinical problem needs an innovative approach, overcoming the limits of traditional cytological diagnostics. Fluorescence laser confocal microscopes (FCM) is a new optical technique for allowing immediate digital imaging of fresh unfixed tissues, and it recently obtained attention for real-time assessment of sample adequacy and diagnostic evaluation for small biopsies and cytological samples. Herein we tested FCM technology for evaluating FNA thyroid samples at the procedure time and to assess the concordance between FCM evaluations, paired conventional cytology, and final histology of removed thyroid gland. We also analyzed the integrity of nucleic acids after FCM evaluation to assure viability for molecular assessment. Our results demonstrated that FCM might improve timely and accurate patient management. ABSTRACT: Thyroid cytological examination, a key tool in preoperative thyroid nodule evaluation, is specific and accurate; some drawbacks are due to inadequate or indeterminate cytological reports and there is a need for an innovative approach overcoming the limits of traditional cytological diagnostics. Fluorescence laser confocal microscopes (FCM) is a new optical technique for allowing immediate digital imaging of fresh unfixed tissues and real-time assessment of sample adequacy and diagnostic evaluation for small biopsies and cytological samples. Currently, there are no data about the use of FCMs in the field of thyroid nodular pathology. The aims of this study were to test FCM technology for evaluating the adequacy of FNA samples at the time of the procedure and to assess the level of concordance between FCM cytological evaluations, paired conventional cytology, and final surgical histology. The secondary aim was to define the integrity of nucleic acids after FCM evaluation through NGS molecular analysis. Sample adequacy was correctly stated. Comparing FCM evaluation with the final histology, all cases resulting in malignant or suspicious for malignancy at FCM, were confirmed to be carcinomas (PPV 100%). In conclusion, we describe a successful application of FCM in thyroid preoperative cytological evaluation, with advantages in immediate adequacy assessment and diagnostic information, while preserving cellular specimens for permanent morphology and molecular analysis, thus improving timely and accurate patient management.