[Osteosarcoma of the skull base: a case report].

Osteosarcoma, usually observed in long bones, is the second most frequent primitive malignant bone tumor after myeloma. The skull base is an exceptional localization. We report a case of skull base osteosarcoma managed in our department. A 23-year-old female was admitted for bilateral epistaxis, headache, decreasing visual acuity then blindness. Physical examination revealed bilateral blindness and exophthalmia. Cranial magnetic resonance imaging showed a voluminous mass in the skull base extending to the nasosinusal area. A rhinoseptal surgical approach was used but the tumor was so huge that excision was impossible. The biopsy identified at an osteoblastic osteosarcoma. Search for extension (chest computed tomography and abdominal ultrasonography) was negative. Chemotherapy was to be delivered before combination chemoradiotherapy but the patient died before any treatment could be started. Osteosarcoma of the skull base is very rare. The treatment is based on surgery which should be as complete as possible followed by chemoradiotherapy. Prognosis is poor. Median survival is around six months.