Purely cystic intraosseous meningioma of the skull: A radiologic conundrum and histologic challenge.

Background: Intraosseous meningiomas and cystic meningiomas are two rare subtypes of meningiomas. Meningiomas can develop with characteristics encompassing both cystic and intraosseous, termed intraosseous cystic meningiomas, that pose a diagnostic challenge. Case Description: We report the case of a 41-year-old woman with a history of hearing loss presented with a left frontal mass that had been present for 12 years. Her history of hearing loss was in the setting of ear infections bilaterally since she was a teenager and was being evaluated by ear, nose, and throat specialists at the time. Initial cranial computed tomography (CT) identified a skull lesion characterized as a benign arachnoid cyst. At that time, no further intervention was deemed necessary. During a future visit with her primary care physician, the patient expressed concern about the potential growth of the mass and a new symptom. This prompted further CT and magnetic resonance imaging (MRI) studies of the brain, and a benign etiology such as an intra-diploic arachnoid cyst was suspected, but the patient was referred to neurosurgery for further evaluation. The patient and neurosurgeon came to the shared decision for surgery, given ongoing symptoms and pursuit of diagnosis. On the day of the operation, a left parietal craniectomy was performed using stereotactic navigation. At follow-up, the patient noted improvement in headache symptoms and was scheduled for a follow-up MRI. Conclusion: This case provides our rare example of a patient presenting with intraosseous cystic meningioma and current reported cases in the literature. The exact natural history of this pathology is not well described, and further research is needed.