Large Intraosseous Schwannoma in Petrous Apex Presenting with Intratumoral Hemorrhage

Intracranial schwannomas are rarely confined to the skull. We here report a large schwannoma localized in the petrous apex that presented with intratumoral hemorrhage. A 35-year-old woman with mild hearing disturbance and ear fullness underwent computed tomography scan and magnetic resonance imaging, which demonstrated a tumor accompanied with intratumoral hematoma in the right petrous apex. Bone marrow was totally destroyed, but the bone cortex was relatively preserved. Pathologic specimen showed that the tumor was composed of proliferation of elongated neoplastic cells and positive for S-100 protein. It showed a nuclear palisading pattern, compatible with schwannoma. The lack of any cranial nerve signs and relative preservation of canals through which cranial nerves pass suggested the neurilemma cells surrounded vessels or mismigrated fetal neurilemma cells in the petrous apex as origin of the tumor. Benign nature of the tumor and total disappearance of the symptoms, supposedly due to the spontaneous absorption of the hematoma, made the patient choose a wait-and-watch approach. Magnetic resonance imaging studied 7 years after the diagnosis showed significant decrease of the tumor volume and disappearance of the hematoma. Although it is a large intraosseous schwannoma in the petrous apex, it has a benign nature, its size is reduced due to the hematoma absorption, and the patient is asymptomatic. We observed the patients for 7 years after the diagnosis.