Efficacy of liquid-based cytology versus conventional smears in FNA samples

Liquid-based cytology (LBC) is fast becoming a useful method in evaluating both gynecological and non-gynecological preparations, including fine needle aspiration (FNA) cytology. Even distribution of cells, decreasing obscuring background elements like blood and mucus, well preserved nuclear and cytoplasmic details and rapid fixation helps in better visualization of cells.

This study was conducted to asses the diagnostic accuracy of liquid-based cytology versus conventional smears in fine needle aspiration samples.

In this prospective study, we had 110 cases, including 30 cases of breast, 40 of lymph node, 10 of salivary glands, 18 of thyroid and 12 of bone and soft tissue. In each case, two passes were performed. The first pass was for conventional preparation (CP) and the second pass yielded material for thin-prep (TP) preparation. Both CP and TP smears were compared for cellularity, background blood and necrotic cell debris, cell architecture, informative background, presence of a monolayer of cells and nuclear and cytoplasmic details by a semiquantitative scoring system. Wilcoxon's signed rank test on an SPSS program was used for statistical analysis.

Diagnostic accuracy was better in LBC smears compared with CP smears due to lack of background debris and better cell morphology, which was performed according to Wilcoxon's signed rank test, yielding a P-value of <0.001. However, in some cases, because of a decrease in cell size, clustering and altered background in LBC, a support of CP was essential.

LBC performed on FNA samples can be a simple and valuable technique. Only in few selected cases, where background factor is an essential diagnostic clue, a combination of both CP and TP is necessary.