Comparison of three cytologic preparation methods and immunocytochemistries to distinguish adenocarcinoma cells from reactive mesothelial cells in serous effusion

We assessed whether a panel of seven antibodies is useful in the differentiation of adenocarcinoma cells (ACCs) from reactive mesothelial cells (RMCs) in effusion samples and to determine optimal specimen preparation conditions for immunocytochemical analysis of effusion samples. Immunocytochemistry (ICC) was performed on three types of effusion preparations from the same effusion specimens: ethanol-fixed smears, ethanol-fixed cell-blocks, and formalin-fixed cell-blocks. Commercially available antibodies MOC-31, Ber-EP4, CA19-9, CEA, EMA, CA125, and HBME-1 were tested on RMCs from four samples of various etiology and 15 samples of adenocarcinoma from various primary sites. Ethanol-fixed smears showed strong immunoreactivity to all antibodies tested. The immunoreactivity of ethanol-fixed and formalin-fixed cell-blocks was significantly lower with all antibodies except CA19-9. Smear preparations are more sensitive than cell-blocks for immunocytochemical study. A panel of antibodies MOC-31, Ber-EP4, CA19-9, and CEA appears to be suitable to distinguish between ACCs and RMCs.