[Intraoperative cytology: the use of Liu's stain for immediate diagnosis].

We prospectively studied 305 fresh specimens submitted for intraoperative frozen section diagnosis. Three types of cytologic preparations, namely touch imprint, smearing, and crush method, were performed to obtain adequate material. Liu's stain, which takes only two minutes and is one of the rapid staining methods of the Romanowsky series, was used for immediate interpretation. The accuracy of diagnosis was measured by comparison with final histological diagnosis. Sensitivity and specificity of intraoperative cytology were 94.9% and 95.6% respectively. The false-positive rate, false-negative rate, and suspicious rate were 0.3%, 1.3%, and 1.6%. In combination of intraoperative cytology and frozen section, sensitivity and specificity became 96% and 96.3% respectively. The cytomorphology of breast, thyroid, lymph node, and ovary is briefly described. Most cases of cytological diagnostic error are found in sarcomas and ovarian tumors. We conclude that Liu's stain is a simple, rapid, and reliable staining method in intraoperative cytological diagnosis. It is apparent that intraoperative cytology is able to provide a useful adjunct to the frozen-section diagnosis and an excellent teaching file for cytopathology.