Hyperostosing meningiomas of the cranial vault with and without tumor mass.

OBJECTIVE: This study represents the first clinical series in the reported literature exclusively concentrating on the clinicoradiological features of non-sphenoidal hyperostosing meningiomas. It attempts to identify the factors that may have an impact on the surgical strategy and results of this unique subgroup of meningiomas. METHODS: In the vault, we distinguished between meningiomas with and without tumor mass according to their thickness (<1.5 vs ≥1.5 cm) and between convexity (lateral) and calvarial (midline) meningiomas according to their location. The clinical, radiological, surgical and prognostic characteristics of the tumors were examined. RESULTS: Over a 10-year period, we observed 24 cases, 18 of which in the convexity (nine without and nine with tumor mass) and six calvarial (one without and five with tumor mass). Six patients presented with neurological signs, while the majority showed bony hyperostosis (n = 19). Brain edema (n = 7) was found only in cases with tumor mass, in all neurologically impaired patients, and only in one intact patient. Total removal was obtained in 92\% patients. Small residual tumors attached to the superior sagittal sinus and perisinusal dura were coagulated in situ and not excised. Morbidity occurred in three symptomatic patients with tumor mass and brain edema (mental confusion in one case and hemiparesis in two cases). Mortality was nil. After a mean follow-up of 4.8 years, three cases relapsed, all of which had initially presented with atypical meningiomas. CONCLUSIONS: The rare hyperostosing cranial vault meningiomas may be classified as being with and without tumor mass. A number of categorical differences exist in their distribution, pattern of hyperostosis, surrounding arachnoidal plane, and their prognosis. Careful preoperative planning aimed at tailoring the extent of tumor removal and reconstruction in the neighboring infiltrated structures enables a good outcome to be achieved.