Anterior Skull Base Rhabdoid Meningioma Masquerading as Esthesioneuroblastoma

Introduction: Radiographic diagnoses of high-grade meningiomas can be complicated by unusually aggressive anatomy. This is particularly true for lesions exhibiting expansile extracranial growth or cystic structures, findings that are often characteristic of rarer tumors. We report for the first time a giant anterior fossa meningioma exhibiting anatomy classically suggestive of esthesioneuroblastoma. Case Report: A 32-year-old man with a 3-year history of bilateral headaches and progressive nasal obstruction presented after a tonic-clonic seizure. Imaging revealed a giant skull base tumor involving the right frontal lobe, anterior fossa floor, frontal and ethmoid sinuses, and nasopharynx. The lesion had an extensive exophytic growth pattern, a nonenhancing peritumoral cyst, bony destruction of the cribriform plate, and absence of hyperostosis. Together, these findings were highly suggestive of an esthesioneuroblastoma. Combined endonasal and open cranial resection with skull base reconstruction were performed. Results: The tumor was identified histopathologically as a WHO grade III rhabdoid meningioma. Postoperative imaging demonstrated complete tumor resection but persistence of the peritumoral cyst. The patient received adjuvant radiotherapy (59.4 Gy IMRT). Follow-up at 12 months revealed partial resolution of the cyst and stable postsurgical changes; the patient has had no postoperative seizures and remains neurologically intact. Conclusion: Skull base meningiomas may present with deceptive imaging characteristics and may mimic a variety of lesions including esthesioneuroblastomas. Even in cases for which radiography restricts the differential diagnosis, aggressive anatomy should not necessarily be considered pathognomonic for rare skull base tumors.