Routine histological examination showed a lesion composed, in some areas, by neoplastic cells which were disposed in lobules with a syncytial pattern with indistinct eosinophilic cytoplasms and round to oval nuclei (Fig. 1); moreover, a transition to cells which had prominent eosinophilic cytoplasm with eccentric nuclei was seen (Fig. 3), while other areas of the tumor had an appearance shown in Fig. 2, Immunohistochemical stains for vimentin (Fig. 4a), epithelial membrane antigen (Fig. 4b) and desmin (Fig. 4c) were performed. In the areas shown in Fig. 2, immunoreactivity for S-100 protein was observed.