Successful treatment of fibrosarcoma in the occipital bone. A case report

•This rare fibrosarcoma case report showed the surgical techniques around mastoid process. Adult type fibrosarcoma is a rare and highly aggressive type of soft tissue tumor. Surgical resection with wide margins is the most effective, but difficult for the skull lesion as to the critical organ nearby. A 27-year-old Japanese woman presented a occipital tumor progressively enlarging for 2 months. CT scan showed an ovoid mass with osteolysis, extending to intracranially and subcutaneous tissue. MRI revealed the tumor involved transverse and sigmoid sinus. The gross total resection was achieved with mastoidectomy. The skull was reconstructed by titanium plate and bone cement. The proton beam irradiated after surgery. Chemotherapeutic agents were not administrated. Single lung metastasis was evident after 1 year later and removed. The patient is good in health at 8 years after initial diagnosis and got a baby. Skull high grade fibrosarcoma was successfully treated by entire surgical removal with proton beam therapy.