[1485] Flow Cytometric Immunophenotyping Is Highly Sensitive for the Detection of Malignant Epithelial Effusions

Vinodh Pillai, Edmund S Cibas, David M Dorfman. Brigham and Women's Hospital, Boston, MA

Background: Epithelial malignancies frequently metastasize to the serous cavities resulting in symptomatic effusions. In many instances, an effusion is the first presentation of a malignancy. Cytology has high specificity (97%) but only moderate sensitivity (58%) for the diagnosis of a malignant effusion. Morphological distinction between reactive mesothelial cells, macrophages, and malignant cells can be difficult, and hypocellular specimens and hemorrhagic effusions can be particularly challenging. Ber-EP4 (EpCAM) is a cell-cell adhesion molecule expressed on all epithelial cells but not on mesothelial cells or hematopoietic cells. Epithelial cells are not a normal component of serous cavity fluids; hence their presence can be used to indicate a malignant effusion. We developed and validated a simple 3 color flow cytometric panel utilizing Ber-EP4 to detect epithelial cells in effusions.
Design: 195 consecutive benign and malignant effusions (pleural, pericardial and peritoneal) received for routine cytologic examination were analyzed by a flow cytometric panel consisting of CD45, CD14, and Ber-EP4. 500,000 events were collected and the proportion of Ber-EP4+ cells was determined from the CD45 and CD14 double-negative population. The gold standard for the presence of a malignant effusion was a combination of clinical, pathological, and radiological data. Effusions due to non-epithelial malignancies and peritoneal washings were excluded from the analysis. For sensitivity and specificity calculations, “atypical” and “suspicious” cytology results were considered benign.
Results: 83 fluids were benign and 76 malignant as judged by follow-up data. Ber-EP4+ cells were detected by flow cytometry in 89.3% of malignant effusions. The sensitivity and specificity of flow cytometry was 89.3% and 97.6% compared to 74.6% and 100% by cytology for the presence of a malignant effusion. Although excluded from sensitivity/specificity calculations, effusions from patients with non-epithelial malignancies showed no Ber-EP4 expression.
Conclusions: Flow cytometric analysis is highly sensitive for the detection of epithelial cells in malignant effusions. While flow cytometry cannot conclusively diagnose the presence of malignant epithelial cells, it can be a useful adjunct to cytomorphology for the diagnosis of a malignant effusion when large numbers of high staining Ber-EP4+ cells are detected. It is particularly useful if the cytology diagnosis is atypical/suspicious or if the cytologic preparations are hypocellular.
Category: Hematopathology

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 233, Wednesday Afternoon


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