Surgical management of meningioma en plaque of the sphenoid ridge

BACKGROUND: Meningioma en plaque represents a morphological subgroup within the meningiomas defined by a carpet or sheet-like lesion that infiltrates the dura and sometimes invades the bone. Differential diagnosis includes fibrous dysplasia, osteoma, and osteoblastic metastasis. This study was conducted to obtain pathological information on patients with meningioma en plaque and to correlate with the surgical management. METHODS: A retrospective review of all the adult operative cases at the University Hospital in a seven and a half-year period from July 1, 1990 to December 31, 1997 identified 150 patients who were operated on for intracranial meningiomas. The medical records were reviewed to identify cases of meningioma en plaque. Forty-seven patients had involvement of the sphenoid ridge and 6 of them fulfill the criteria for meningioma en plaque. RESULTS: All 6 patients with meningiomas en plaque were female and had hyperostosis of the sphenoid bone. In 5 of them, the bone was sent for histopathological examination. Four of those had infiltration of the bone by meningioma cells. Proptosis was the most common presentation. Half of the patients presented with visual disturbances that improved after surgery. All patients were operated using a fronto-temporal approach with orbital decompression. CONCLUSION: All the involved bone should be removed to prevent recurrence. In those cases with involvement of the cavernous sinus and/or the orbital apex, a subtotal but extensive removal combined with bony decompression of the cranial nerves at the superior orbital fissure and optic canal frequently produces good functional and cosmetic results.