Benign purely intraosseous meningioma of the skull: Diagnosis and surgical outcomes.

Primary intraosseous meningioma (PIM) is a rare subtype of extradural meningiomas that originates within bone. We aimed to characterize the clinical, radiographic, and pathologic features of PIM and the resulting outcomes following resection. Herein we examined a retrospective case series of all patients with a pathologically confirmed WHO grade I PIM that were managed at one of three tertiary care centers. Patients with tumors that demonstrated extraosseous extension or involvement of the dura mater were excluded. The main outcomes included surgical safety and duration of local tumor control. Nine patients were identified with benign PIMs, presenting with headaches or painless enlarging subcutaneous masses if involving the calvarium or with neurologic deficits if involving the skull base, or otherwise incidentally identified. Surgery was pursued for symptomatic relief and/or tissue diagnosis. Lesions were evaluated by radiographic imaging - including sensitive detection by plain X-ray films - and definitive diagnosis ascertained by histopathological examination. Maximal resection of both calvarial and skull base lesions was safely tolerated. PIM represents a rare benign skull lesion, whose identification depends on the integration of radiographic findings with intraoperative findings and histopathological confirmation; it should be considered in the differential for slow-growing expansile intraosseous lesions of the skull.