To Get the Most out of the Least: BRAF Molecular Evaluation in Melanoma Metastases on Cell Suspension from Fine Needle Aspiration Cytology Needle Rinses

Abstract

Introduction: Cytological samples from cutaneous melanoma (CM) metastases may be the only biomaterial available for diagnostic and predictive purpose in the clinical practice. BRAF evaluation from cytological samples actually implies the loss of one or more diagnostic smears, or the execution of one or more passes to obtain dedicated cytological samples. We tested BRAF molecular evaluation in CM metastases on cell suspension obtained from fine needle aspiration cytology (FNAC) needle rinses. Methods: Forty-two patients with lymph node enlargements and a previous CM were enrolled. Patients were submitted to FNAC, and direct smears and cell-block were prepared for diagnostic purpose. The needle was carefully flushed in a vial containing 350 μL of nuclease-free water and a cell suspension was obtained for BRAF molecular evaluation. Molecular evaluation was also performed on histological samples for statistics. Results: The series included 35 CM metastases and 7 reactive lymphadenopathies. Three cases resulted inadequate and adequacy was 92.9%. BRAF V600E/Ec mutations were found in 7 out of 32 (21.9%) CM metastases cases. BRAF mutations other than V600E/Ec were found in 2 out of 32 (6.25%) cases. Sensitivity, specificity, positive predictive value, and negative predictive value resulted 100%. Conclusion: BRAF molecular evaluation in CM metastases on cell suspension obtained from FNAC needle rinses is a time-sparing and accurate technique allowing to spare biomaterial in the clinical setting.