Comparison of aspiration, touch and scrape preparations simultaneously obtained from surgically excised specimens. Effect of different methods of smear preparation on interpretive cytologic features.

OBJECTIVE: To determine whether three commonly used methods of obtaining and preparing cells for cytologic evaluation--touch preparation (TP), fine needle aspiration (FNA) and scrape preparation--yield essentially comparable material for evaluation or whether important differences exist between them that may influence interpretation. STUDY
DESIGN: FNA, TP and scrape preparations were made simultaneously on surgically excised specimens. Thirty breast, 6 lung and 12 colon lesions were studied. Each slide was assessed for qualitative and quantitative features. Cellularity was semiquantitatively scored.
RESULTS: Scrape preparations were the most cellular (P < .0001). Scrape and TPs often had larger tissue fragments than FNA. However, fragmentation of epithelial groups into smaller clusters and single cells was often noted on scrape preparations. FNAs tended to have cleaner backgrounds than the other two methods.
CONCLUSION: Most often, there are few differences between smears prepared by the three techniques studied. However, scrape preparations may yield smears with smaller clusters and single cells as compared to the other two methods; that is a potential source of diagnostic confusion, particularly with respect to benign breast lesions. Scrape preparations uniformly yield more cellular smears. To the extent that cellularity is an interpretive factor in assessing cytologic specimens, it is important to be aware of the increased cellularity of scrape preparations as compared to the other two techniques.