CEACAM5 and neoplasm: Immunohistochemically, the tumour strongly reacted with mithochondrial antigen (Figure 2a), keratin (Figure 2b), alpha-1-antichymotrypsin (Figure 2c and 2d), but was negative for smooth muscle actin, vimentin and carcinoembryonal antigen (CEA) and S-100 protein (S-100).