TTF1 and mesothelioma: However, it was distinguished from mesothelioma by microscopic features and the expression in IHC staining which was positive for chromogranin, synaptophysin, and CD56 (which is in favor of SCC) but negative for anti-mesothelial cell antibody.[15] Though the expression of TTF-1 in our case was positive, it is controversial to some degree.