SMN1 and malignant peripheral nerve sheath tumor: Immunohistochemically, schwannomas consistently express S100, SOX10, and vimentin, which are useful in establishing the diagnosis [10]. These hallmarks help distinguish benign schwannoma from malignant differentials such as malignant peripheral nerve sheath tumor, characterized by reduced/heterogeneous S100/SOX10 expression, higher mitotic activity, and necrosis, and from non-neurogenic sarcomas [e.g., leiomyosarcoma, smooth muscle actin (SMA)/desmin positive or gastrointestinal stromal tumor (GIST) c-KIT/CD117 (KIT)/ Discovered On GIST-1 (DOG1) positive].