[353] Tissue Processor Protocol for Cytologic Preparations Improves Immunohistochemistry Results

TA Archibald, P Kerble, N Parker, C Curran, AR Perez-Atayde, HP Kozakewich. Children's Hospital Boston, Boston, MA

Background: Immunohistochemistry (IH) on touch and cytospin preparations is not commonly utilized because the procedure is usually not standardized for them and the results often do not correspond to those expected or to those observed in formalin-fixed paraffin-embedded tissue sections. We sought to determine whether the sensitivity and reliability of IH on cytologic preparations might be improved if they are subjected to pre-staining conditions similar to those used for formalin-fixed paraffin-embedded tissue.
Design: We obtained 2 sets of 45 air-dried touch or cytospin preparations from various tumors (n=12), body fluids (n=3) or normal tissue (n=3). One member of a pair was placed in a metal slide holder accompanying formalin-fixed tissue cassettes for routine overnight processing while the other was kept unfixed at room temperature. The following morning, IH was performed on the slide pair using an automatic immunostainer and stained with 1 of 26 antibodies commonly used to detect intermediate filaments and hematologic, neural, oncologic and other antigens. The antibody selected for each slide pair was one in which the corresponding antigen was anticipated to be present in that particular tumor type, body fluid or normal tissue. The slides were examined microscopically in a double blind fashion and semiquantitatively assigned to a quartile depending on the percentage of immunopositive cells. The staining intensity was graded as 0-3.
Results: Within the slide pairs, 58% of the tissue processor slides had a greater percentage of immunoreactive cells, 35% an equal percentage, and 7% a lesser percentage. Also, the staining intensity was greater in 56% of the tissue processor slides, identical in 40% and less in 4%. In both tumoral, body fluid and normal tissue specimens, the results in the tissue processor cytologic preparations were judged to be similar to those anticipated or observed (when available) in formalin-fixed paraffin-embedded tissue sections.
Conclusions: Subjecting cytologic preparations to tissue processor conditions helps equalize the pre-staining influences so that the IH protocol used for formalin-fixed paraffin-embedded tissue can be reliably applied to cytologic preparations. The cytologic IH results are similar to those observed in formalin-fixed paraffin-embedded tissue.
Category: Cytopathology

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 69, Wednesday Afternoon