Tumour location and description. (A) Magnetic resonance image showing all tumors developed in patient’s right leg and picture details of one of the resected schwannomas. (B) Scheme of the location of the two resected schwanomas. The tumor located at the right internal malleolus (T1) and the one on the inside of the right foot (T2) were surgically removed and processed to obtain DNA and RNA from both samples. (C) Immunohistochemical characterization of schwannomas surgically removed. Top image shows that T1 was mainly composed of large spindle cells with palisaded nuclei and occasional large, hyperchromatic nuclei (degenerative atypia). In the middle image it can be seen that T1 tumor cells showed intense and diffuse nuclear and cytoplasmic immunoreaction for S100. Bottom image illustrates a SMARCB1 staining of T1 revealing a mosaic pattern of immunoreactivity.