KIT and schwannoma: In addition, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has been shown to aid in the characterisation of schwannomas and other submucosal lesions of the upper GI tract but has limited accuracy [10]. Therefore, to get a diagnosis of schwannoma immunohistochemical staining is required; positivity for S100 protein or Sox10 supports the possibility of nerve sheath origins, but staining needs to be negative for actin, desmin, caldesmon, DOG-1 and CD117, which support smooth muscle origins [2].