Comparison of different preparation techniques for fine needle aspiration specimens. A semiquantitative and statistical analysis.

Different options exist for preparing fine needle aspiration specimens (FNAS). To compare direct smears and cytocentrifugation specimens, we prospectively obtained FNAS from 38 operative cases, making alcohol-fixed (DIR) and air-dried (AIR) direct smears and collecting additional passes in 50% ethanol (ETH), Saccomanno's solution (SAC) and Hanks' Balanced Salt Solution (HBSS). All slides were stained with Papanicolaou stain except AIR, which were stained with Diff-Quik. We evaluated cellularity, nuclear and cytoplasmic preservation, percent single cells, background and degree of three-dimensionality on a 0-3+ scale and rendered an independent diagnosis for each medium. Statistical analysis of differences between techniques was performed utilizing the paired t test. Cellularity was significantly decreased for ETH, HBSS and SAC as compared to DIFF and DIR. Nuclear preservation was best for DIR and inferior for AIR, ETH, SAC and HBSS. Background was best seen in DIR and AIR as compared to ETH and SAC. HBSS was significantly inferior to DIR but not to AIR. There were no significant differences in cytoplasmic preservation and percent single cells. Three-dimensionality was increased for ETH and SAC but not for HBSS. The ability to make a definitive diagnosis was significantly inferior only for HBSS and SAC as compared to AIR. Direct smears made by cytotechnologists or pathologists are better than Cytospin specimens. However, despite their inherent disadvantages, rinse techniques may be advantageous when specimens are collected solely by clinicians.