Title : Flow cytometry for diagnosing malignant carcinomatous effusions
Abstract:
Background: The lecture will introduce the audience to commonly utilized techniques for Cytology of malignant fluids including cytospin, cell block and immunohistochemistry. The advantages and limitations of the techniques will be discussed. Further, basics of flow cytometry (FCM) and application of FCM for detecting malignant epithelial cells will be presented through a research study conducted on 96 serous fluids.
Method: FCM assessment was performed by using epithelial cell adhesion molecule (EpCAM) and MUC-1 (in a subgroup of cases) as epithelial markers and CD45 and CD14 as leucocyte markers. The percentage of EpCAM positivity and MUC-1 positivity was calculated in the CD14 and CD45 dual negative population by selective gating. The findings were then correlated with the defined gold standard criteria. FCM was performed on a 3 laser 10 colour flow cytometer equipped with acquisition and analysis software.
Results: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy for EpCAM was determined to be 92.06%, 96.96%, 98.31%, 86.48%, and 93.75%, respectively, while that for MUC-1 the sensitivity and specificity were slightly lower at 79.16% and 93.75%. Combining FCM with cytomorphology significantly enhanced these metrics, resulting in sensitivity, specificity, PPV, NPV, and diagnostic accuracy of 95.3%, 100%, 100%, 91.4%, and 96.8%, respectively.
Conclusions The study highlighted the importance of multicolored flowcytometric analysis in detecting epithelial malignancies in effusions specially in cases belonging to the atypia of undetermined significance and suspicious for malignancy categories and in cases with strong clinical suspicion of malignancy with negative fluid cytology. We recommend the combined use of FCM and cytology for this specific subgroup of patients in routine clinical practice for fast and accurate reporting.
