Immunocytochemical differentiation of reactive mesothelial cells and adenocarcinoma cells in serous effusions with the use of carcinoembryonic antigen and fibronectin.

Ninety effusions from patients with breast and ovarian cancer were studied cytologically and classified as benign, suspicious or malignant, and the same samples were studied for carcinoembryonic antigen (CEA) and fibronectin (F) immunostaining. The combination F positive/CEA negative was found to have 100% specificity and 92.3% sensitivity in patients with benign or reactive effusions, and F negative/CEA positive 85.7% specificity and 80.7% sensitivity for malignancy. Immunostaining provides valuable supplementary information in cytologically suspicious patients. In the presence of F negative/CEA negative effusions, it is probable that insufficient cellular material is present for either a cytologic or immunostaining diagnosis.