Optimal Recovery of DNA for Polymerase Chain Reaction–Based Assays from Fine Needle Aspirates

Abstract

To assess the ideal preparation for molecular techniques applied to cytologic specimens using polymerase chain reaction (PCR) on different types of cytologic preparations with specimens obtained from fine needle aspiration biopsy (FNAB). Besides conventional cytologic examination, PCR was performed on 30 consecutive cases of FNAB to analyze the beta-actin gene in four types of cytologic preparations, including fresh samples, previously stained Papanicolaou and Diff-Quik routine smears and cell blocks. Cellularity and cytologic findings were correlated with PCR results. The beta-actin gene was successfully amplified from all cases studied. Cellularity of the samples correlated directly with PCR results except for one case of metastatic melanoma with intense pigment retention. All specimens showed equivalent results as compared to fresh samples. Generally cell blocks were less cellular and consequently less effective. All conventional cytologic preparations tested were suitable for PCR-based assays when cellularity was adequate. Alcohol-fixed and air-dried smears can be successfully used for PCR studies, providing rapid and simple specimens for molecular studies, which can add important information concerning diagnosis, prognosis and management.