Differential expression of CD44s and CD44v3-10 in adenocarcinoma cells andreactive mesothelial cells in effusions

The detection of malignant cells in serous effusions obtained from patients diagnosed with cancer marks the presence of metastatic disease and is asso ciated with a poor outcome. The purpose of this study was to evaluate the r ole of CD44s and CD44v isoforms in the distinction between mesothelial cell s and malignant epithelial tells in effusions. Fifty-nine fresh pleural and peritoneal effusions were studied. These consisted of 41 specimens from pa tients with known gynecological neoplasms, 9 from patients diagnosed with b reast adenocarcinoma, and 9 effusions from patients with various non-gyneco logical malignancies or tumors of unknown origin. Forty-three effusions con tained malignant/atypical epithelial cells, and 16 effusions were diagnosed as reactive. Three effusions contained exclusively malignant cells. Specim ens were stained with anti-CD44s, v3, v5, v6, v7 and v3-10. The presence of staining in cancer cells, benign mesothelial cells and lymphocytes was eva luated. CD44s immunoreactivity was seen in 10 of 43 (23%) cases in malignan t/atypical epithelial cells and in 53 of 56 (94%) cases in benign cells. In contrast, CD44v3-10 was seen in 23 of 43 (55%) cases in malignant/atypical epithelial cells and in 3 of 56 (6%) cases in benign cells. We advocate th e use of CD44s and CD44v3-10 immunostaining in diagnostic evaluation of dif ficult serous effusions.