Histopathological examination revealed two distinct tumor components in the left lobe: immunohistochemistry revealed a PEComa component (HMB45+/SMA+/Desmin+, Ki-67 about 50%, P53 missense mutation) and a follicular carcinoma component (TTF-1+/PAX8+/TPO+, Ki-67 about 3% and P53 wild-type). This evidence concerns the gene PAX8 and thyroid gland follicular carcinoma.