Utility of a limited panel of calretinin and Ber-EP4 immunocytochemistry on cytospin preparation of serous effusions: A cost-effective measure in resource-limited settings

BACKGROUND: Differentiation between reactive, but morphologically atypical, mesothelial cells and adenocarcinoma in effusions can be problematic. Elaborate immunohistochemical panels have been devised. Techniques like DNA analysis, flow/image cytometry, and K-ras mutation analysis are research oriented and difficult to perform in routine, especially in resource-poor centers. We evaluated the efficacy of a limited two-antibody panel comprising calretinin and Ber-EP4 on cytospin and cell block preparations, in 100 effusion samples. MATERIALS AND METHODS: Fifty cases of reactive mesothelial hyperplasia and 50 cases of adenocarcinoma diagnosed by cytomorphology in ascitic/pleural fluid specimens over a 2-year period were assessed. The diagnoses were confirmed by clinical/histopathologic correlation. Cytospin smears were made in all. Cell blocks were prepared, wherever adequate fluid was available. Immunocytochemistry (ICC) for calretinin and Ber-EP4 was performed. RESULTS: Forty-five of the reactive effusion cases (90%) were calretinin reactive and Ber-EP4 negative. Among the adenocarcinoma cases, 49 (98%) were calretinin negative but Ber-EP4 positive. Thus, both calretinin and Ber-EP4 had a high sensitivity (90% and 98%, respectively), as well as a high specificity (100% and 86%, respectively). In the 21 reactive mesothelial cases, whose cell blocks were made, results were comparable to those on cytospin. However, of the 19 adenocarcinoma cases in which cell blocks were prepared, all were Ber-EP4 immunopositive except for three, which were positive on cytospin, implying false-negative results on cell blocks. CONCLUSIONS: A limited panel of two monoclonal antibodies, calretinin and Ber-EP4, may be useful in cytology, as a “primary antibody panel”, for accurate diagnosis and patient management. Additionally, ICC can be performed easily on cytospin preparations, which gave results comparable to cell blocks in our study.