Application of multicolour flow cytometry in the detection of metastatic carcinoma in serous effusions: Special emphasis in atypical cytology.

INTRODUCTION

We evaluated the role of simultaneous use of multiple antibodies in flow cytometry (FCM) to detect metastatic carcinomas in effusion samples.

METHODS

Cytological examination of 75 successive cases of effusion samples was performed. There were 48 peritoneal, 26 pleural and one pericardial fluid. Multi-coloured FCM examination was undertaken using a cocktail of CD45, CD14 and epithelial cell adhesion molecule (EpCAM), antibodies tagged with different fluorochromes. The percentage of EpCAM positivity was calculated in the CD45 and CD14 dual negative population by selective gating. The EpCAM value was correlated with the cytological findings, follow-up data and MOC-31 immunostaining.

RESULTS

There were 20 benign, 35 malignant and 20 atypical cases diagnosed on cytomorphology. The primary sources of carcinomas were mainly from the ovary, followed by lung, gall bladder, intestine and other areas. Out of 20 cytologically benign cases, there were two malignant cases on the final follow-up, and EpCAM on FCM picked up all 18 benign cases and one malignant case. Out of 35 cytologically detected malignant cases, EpCAM picked up 32 malignant cases. The EpCAM detected 15/18 malignant and both benign cases out of 20 cytological atypical cases. EpCAM antibody by FCM showed 87% sensitivity, 100% specificity, 100% positive predictive value and 74% negative predictive value.

CONCLUSION

This comprehensive study highlights the potential use of multi-coloured FCM along with cytological examination to diagnose metastatic carcinoma in effusion samples. Multi-coloured FCM is rapid and quantitative and is helpful in atypical cases.