Test Details: Immunohistochemical testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody. SMA is widely used antibody for the diagnosis of smooth muscle, myoepithelial and myofibroblastic tumours. The expression of SMA can be found in some tumours with a similar morphology other than smooth muscle tumours, including endometrial stromal tumours, synovial sarcoma, GISTs and sarcomatous mesothelioma.