[1954] Flow Cytometric Analysis of Ep-CAM Expression Is a Useful Adjunct in the Detection of Metastatic Carcinoma in Fine Needle Aspirates and Body Fluids

L Vila, P Boonsakan, Y Li, RC Braylan, SZ Al-Quran. Univ. of Florida, Gainesville, FL

Background: Few studies have shown that flow cytometric (FCM) analysis can be used in the identification of non-hematopoietic malignancies. Ber-EP4 monoclonal antibody (AB) is directed against Ep-CAM glycoproteins expressed on virtually all epithelial cells, but is lacking on non-epithelial cells including mesothelial cells. It has been used to differentiate adenocarcinomas from reactive and neoplastic mesothelial cells. The aim of our study was to evaluate the utility of FCM analysis of Ep-CAM expression in the detection of metastatic carcinoma in fine needle aspirates (FNAs) and body fluids (BFs).
Design: We searched for FNAs and BFs received in our laboratory between 2008-2009 that had FCM with Ber-EP4 AB. In all cases, concurrent cytology, including cell block when available, was separately reviewed by cytopathologists. Neoplastic epithelial cells were initially identified by combined analysis of light scatter and CD45 (large CD45-negative cells), and subsequently confirmed by staining with Ber-EP4 FITC AB. Other informative antigens (CD56, CD38, CD117, CD15) were analyzed when cells were available.

Results: We studied 30 cases including: 18 FNAs (11 lymph nodes, 2 mediastinal, 1 submandibular, 1 lung, 1 pancreas, and 2 liver masses) and 12 BFs (6 pleural, 1 peritoneal, 1 pericardial, and 4 CSF). Metastatic carcinoma was identified in 25 cases by Ber-EP4 positivity. In one case, large CD45- and CD56+ cells, consistent with metastatic carcinoma, were identified by FCM but were Ber-EP4-. Concurrent cytology diagnoses were as follows: positive in 10 cases (confirmed by biopsy in 2 cases), indeterminate/suspicious in 7 cases (confirmed by biopsy in 4 cases), and negative in 4 cases (biopsy and/or repeat cytology showed metastatic carcinoma in all). Five cases did not have concurrent cytology, but malignant cells were identified in our cytospin preparation. Four cases were negative both by FCM/Ber-EP4 and cytology.
Conclusions: FCM analysis of Ep-CAM expression with Ber-EP4 AB can serve as a useful adjunct to diagnostic cytopathology, and in some cases may be superior to morphologic examination, in detection of metastatic carcinoma in small FNA samples and body fluids.
Category: Techniques

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 260, Monday Morning


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