Use of a panel of markers in the differential diagnosis of adenocarcinoma and reactive mesothelial cells in fluid cytology

To evaluate the use of a panel of markers to differentiate adenocarcinoma a nd the reactive/ inflammatory process in fluid cytology, we stained 29 form alin-fixed, paraffin-embedded cell blocks of effusion fluid from. patients with metastatic adenocarcinoma and 24 cell blocks from patients with benign effusion with mucicarmine and antibodies to carcinoembryonic antigen (CEA) , B72.3, and calretinin. Positive staining with CEA, B72.3, and mucicarmine was seen in 22 (76%), 20 (69%), and 18 (62%) adenocarcinoma cases, respect ively. All except 1 adenocarcinoma was negative for calretinin. No benign c ases were positive for B72.3 and mucicarmine. In 1 benign case, scattered e pithelial cells demonstrated weak positivity for CEA. The majority of combi nations were 100% specific for adenocarcinoma. The highest sensitivity (86% ) for adenocarcinomas was achieved with the staining combination of negativ e for calretinin and positive for any adenocarcinoma marker (CEA, B72.3, or mucicarmine). The use of a panel of markers that recognize adenocarcinoma and mesothelial cells is useful in the differential diagnosis between metas tatic adenocarcinoma and the reactive/inflammatory process. The profile of positive staining with at least one of the adenocarcinoma markers and negat ive calretinin staining is highly specific and sensitive for identifying ad enocarcinoma in fluid cytology.