Meningioma: More Than A Bump the Head

A 77-year-old woman was concerned about a "bump" on her head. The asymptomatic mass had been present for 4 years and had slowly enlarged.

John Whyte, MD, and Douglas Beall, MD, of Washington, DC, write that CT scans of the head revealed marked hyperostosis of the calvaria in the right paracentral region of the posterior parietal bone. The hyperostosis was focal and appeared to adhere to the outer table of the calvaria. There was no evidence of an abnormal mass lesion in an intra-axial or extra-axial location.

The CT scanogram demonstrated the 3.5-cm hyperostotic cap of bone along the posterior parietal portion of the calvaria (A). The CT section through the superior portion of the calvaria with bone window parameters showed the thickened portion of the calvaria and minimal ossification along the parafalcine region posteriorly (B). The CT section of the same area with soft tissue (brain) parameters showed unremarkable cerebral parenchyma immediately adjacent to the hyperostosis and the parafalcine ossification (C).

MRI scans revealed mild dural thickening and enhancement just subjacent to the bony mass and corroborated the region of hyperostosis on the CT scans.

The patient underwent a craniotomy. A flat, plaque-like tumor under the bony mass was removed. Frozen section examination and histopathologic evaluation revealed a meningioma.

Meningiomas are common primary intracranial tumors; they represent 15% of brain tumors.¹ They are twice as common in women as in men. Hyperostosis, which often causes exostosis, has been associated with intracranial meningioma. Typically, hyperostosis results from tumor invasion of the bone. The penetration of the skull can be extensive, with marked thickening of bone and even osteoblastic formation. Erosion of bone is rare. Some meningiomas produce alkaline phosphatase, which has ossifying properties.

An en plaque meningioma is a flat lesion that grows radially along the dural structures. Infiltration of the dura by the meningioma often causes hyperostosis and may produce marked formation of new bone, as was seen in this patient. Dural thickening can occur in other disorders, such as granulomatous meningitis, extramedullary hemopoiesis, and leptomeningeal fibrosis. Dural thickening in association with calvarial hyperostosis is characteristic of an en plaque meningioma.

This patient was discharged after 3 days. Her postoperative course was uneventful. Follow-up imaging revealed no evidence of recurrence. Further follow-up imaging will be performed over the next 5 years.

References:

REFERENCE:

1.

Grant FG. A study of the results of surgical treatment in 2,326 consecutive patients with brain tumor.

J Neurosurg.

1956;13:479-488.