Diagnostic markers used in the differential diagnosis between DMPM and serous carcinoma. A large number of tumor cells is seen in Pap-stained slides and a HE-stained section from a cell block from a DMPM effusion. DMPM expresses EMA, calretinin and CK5/6 and, unlike reactive mesothelial cells, it only has focal desmin expression. Ber-EP4 and MOC-31 stain only a few cells, whereas the B72.3 stain is negative. Scale bar = 50 µm.