Giant osteoid osteoma of the posterior skull base. A case report and literature review

Background - Osteoid osteoma is a benign bone neoplasm which is seen in the long bones. It is rarely described in the cranium. Posterior skull base osteoma is extremely rare and has been anecdotally reported. Observation. - We report a rare case of a large osteoid osteoma of the petro-occipital area in a 26-year-old man. He presented with clinical sign of raised intracranial pressure, cerebellar symptoms and large left retro-auricular swelling. Cerebral MRI shows a giant lesion of the posterior cerebral fossa with destruction of the left petrous bone and the left side of the occipital bone. Large excision was performed through a retro-sigmoid approach. In our knowledge, there is no similar case reported in the literature to date. Conclusion. - Although benign and rare, osteoid osteoma can present with neurological deficit due to mass effect and involvement of nervous structures especially in the posterior skull base.