Moc-31, fibronectin and CEA in the differential diagnosis of malignant effusions: an immunocytochemical study

In discriminating benign and malignant origins of cytologically suspicious effusion smears a panel of antibodies against carcinoembryonic antigen (CEA), Fibronectin (F) and MOC-31 was used with immuno-cytochemical techniques. One hundred and thirty seven effusions were studied of which 107 had a malignant and 30 a benign aetiology as determined by clinical and histological examination. Cytologically 24 were diagnosed as benign, 97 as malignant and 14 as suspicious. Staining for F was positive in all effusions of benign and 3 of malignant origin. MOC-31 was positive in 95 (88.8%) of effusions of malignant origin but none of benign origin. Positive CEA was observed in 43% of effusions of malignant origin and in 10 of benign origin. The combination of MOC-31 positivity measured the sensitivity and specificity of the cytological examination in cases where the cytological examination result was suspicious as did F positivity improve the sensitivity for a benign origin of the effusion. Positivity or negativity for CEA is less valuable than the other parameters.