ACTA1 and leiomyosarcoma: Immunohistological diagnosis is very useful in the identification of gastrointestinal mesenchymal tumors, and as α-SMA, desmin, and h-caldesmon are positive in most cases of leiomyosarcoma, it is necessary to exclude GISTs and neurogenic tumors according to CD34 and the S-100 protein negativity, respectively [5].