Fronto-orbito-ethmoidal intradiploic meningiomas: A case study with systematic review

Background: Primary intradiploic meningiomas, extra-axial tumors arising primarily in the skull, are rare. The authors reported a complex case of intradiploic intraosseous metaplastic meningioma of the left medial wall and orbital roof with the left frontal sinus invasion and left ethmoidal body bone substitution. The authors also conducted a systematic review concerning diagnosis and management of patients affected by purely calvarial intradiploic meningiomas along with a focus on fronto-orbito-ethmoidal ones. Methods: A literature search was conducted using PubMed and Scopus databases according to preferred reporting items for systematic reviews and meta-analysis statement and with the following Mesh terms: Intradiploic, intraosseous, calvarial, and meningioma. Eligibility criteria were limited by the nature of existing literature on intradiploic meningiomas, consisting of only case series, and case reports. Results: A total of 128 published studies were identified through our search. 41 studies were included in this systematic review, 59 patients with a female/male ratio of 1.2/1. The mean age of the patients is of 47.69 years (range 3-84 years). Only seven out of 59 patients (11.9%) presented a complex intradiploic meningioma located in fronto-orbito-ethmoidal region like our case. In almost all patients, a gross-total resection was performed (96.6%) and only in two patients (3.4%) a subtotal resection was achieved. Conclusion: The authors shared this successfully treated case to add to the overall clinical experience in the management of this rare subtype tumor, with the hope that more studies are conducted to further address the mechanism of intradiploic meningiomas development.