Immunocytochemistry performed on the cell-transferred direct smears of the fine-needle aspirates: a comparison study with the corresponding formalin-fixed paraffin-embedded tissue.

Immunocytochemistry (ICC) performed on the cell-transferred cytologic smears (CTCS) of fine-needle aspiration (FNA) is useful when the cell blocks lack adequate material. The comparison of the ICC results from the CTCS of FNA with the corresponding formalin-fixed paraffin-embedded tissue (FFPE) has not been reported previously. We applied 12 commonly used ICC antibodies on 160 pieces of ethanol-fixed, cell-transferred Papanicolaou-stained smears obtained from 42 FNA specimens and compared the staining results with the corresponding FFPE on which the same panel of immunostains was performed. Of the 160 pieces of transferred materials, only 3 (1.9%) were lost during specimen processing. In total, 153 of 157 (97.5%) showed staining results that agreed with the corresponding FFPE, including 78 of 81 positive staining and 75 of 76 negative staining cases. ICC performed on the cell-transferred FNA smears is reliable and shows staining results highly comparable with the corresponding FFPE tissue.