Histological findings. (A) Spindle cells neoplasms with expansive growth (Hematoxylin and eosin stain, original magnification 100×). (B) Coagulative necrosis (yellow arrow) (Hematoxylin and eosin stain, original magnification 100×). (C) Hyalinization of the stroma (red arrow) (Hematoxylin and eosin stain, original magnification 100×). (D) Neoplastic cells with nuclear atypia and mitotic figures (Hematoxylin and eosin stain, original magnification 200×). (E) Immunohistochemical positivity for smooth muscle actin (Immunohistochemical stain, original magnification 100×). (F) Immunohistochemical positivity for desmin (Immunohistochemical stain, original magnification 100×).