Cytological and Immunocytochemical Study on Mesothelial Cells and Metastatic Adenocarcinoma Cells inPleural and Peritoneal Effusions.

Cytological evaluation of serous effusions often possesses difficulties to the pathologists.Serous effusions are common clinical problems and can be simply divided into benign and alignant Differentiation between the two kinds of effusions is very important for diagnosis, treatment and prognostic evaluation.The cytologic differential diagnosis of mesothelial cellsand adenocarcinoma in fluid specimens can be challenging due to the overlap in the morphologicfeatures of both.Various ancillary studies have been used to increase thediagnostic accuracy of cytology. Immunocytochemicalanalysis is the most commonly used special technique andoften involves the use of a panel of antibodies. Aim of the study: To evaluate the sensitivity and specificity of Calretinin and Carcinoembryonic antigenas immunocytochemical markers in distinguishing mesothelial cells from metastatic adenocarcinoma cells in effusions with equivocal cytomorphological findings using (routine Papanicolaou stain). Patients, Materials, and Methods: During the period from the first of December 2010 to the end of June 2011, (50) patients presented with effusions (26 pleural and 24 peritoneal), seen at Al-Kadhimya Teaching Hospital were included in this prospective study. Effusion fluids were aspirated and processed for both conventional cytological methods using Papanicolaou- stain, and immunocytochemical staining with anti (Calretinin and CEA). Results: After routine cytological evaluation, the cases were categorized as reactive, suspicious and malignant.The diagnoses were confirmed by clinical and histopathological correlation which revealed 20 benign and 30 metastatic adenocarcinoma effusions. The sensitivity of cytology for the detection of malignant cells was 76.67%, specificity 100% with an accuracy of 86%.Calretininemerged as a 100% specific and 90% sensitive marker for mesothelial cells.The sensitivity of CEA for adenocarcinoma cells was 70% and specificity was 100%. When both cytology andimmunocytochemistry results were considered in conjunction, the sensitivity for the detection of malignancyincreased to 96.67%, specificity 100% and an accuracy of 98%. Conclusions:
Calretinin and CEA were found to be useful markers in the differentiation of reactive mesothelial cells from metastatic adenocarcinoma cells in smears prepared from body fluids, and combination of both cytology and immunocytochemical studies using the two markers can greatly enhance the diagnostic accuracy, sensitivityandspecificityin malignant effusions.