Fig. 4

Photomicrographs of the resected tissue. Cross-section of the tumor is largely composed of bundles of muscle fibers intimately admixed with nerve fibers (a). Peripheral nerve bundles and strongly eosinophilic fibrous structures can be observed among myofascicles (b). Myofibers with various diameters in the interstitium were confirmed to be smooth muscle structures. strongly positive for desmin (c) and Caldesmon (d). S100 (e) and NSE (f) immunohistochemical stain highlights the embedded neurofibrils and small nerve fibers travelling through the muscle fibers. NF (g) immunohistochemistry stain is faintly labelled indicating the location of neurofilament