Immunostaining of cytology smears: A comparative study to identify the most suitable method of smear preparation and fixation with reference to commonly used immunomarkers



As an extension of our previous study (Shidham et al., Acta Cytol 2000;44:1015–1022), we evaluated the interference by methods of cytology smear preparation on the immunoreactivity of cytokeratin-7, cytokeratin-20, estrogen receptor, progesterone receptor, chromogranin, synaptophysin, and vimentin. Scrape cytology smears of 34 fresh specimens submitted for intraoperative consultation were studied. They were processed by three different methods—A: wet-fixed in 95% ethanol; B: air-dried saline rehydrated smears fixed in alcoholic formalin; and C: air-dried saline rehydrated smears fixed in 95% ethanol with 5% acetic acid. The intensity scores of immunostaining were estimated semiquantitatively and compared with corresponding formalin-fixed paraffin-embedded tissue sections (FPTS). Except vimentin, all immunomarkers showed higher intensity scores with method A or B than with method C. Vimentin showed the best results with method A. Our results indicate that the immunoreactivity pattern with each immunomarker is affected by the method of cytology smear processing. Most importantly, method C, which is the desired choice for cytomorphological staining, was not suitable for immunostaining. Diagn. Cytopathol. 2003;29:217–221. © 2003 Wiley-Liss, Inc.