Does bony hyperostosis in intracranial meningioma signify tumor invasion A radio-pathologic study

Background: While operating intracranial meningiomas, neurosurgeons commonly drill the hyperostotic bone and put the bone flap back. Objective: To determine whether bony changes seen in meningioma are due to tumor invasion or reactionary changes. Materials and Methods: This prospective study, conducted over 10 months (October 2010- July 2011) included consecutive patients with intracranial meningiomas. Preoperatively, computed tomography (CT) was done in all patients and reviewed by two neurosurgeons for associated bony hyperostosis. During surgery, a piece of bone showing hyperostosis was taken for histopathological evaluation for tumor invasion. In absence of hyperostosis, the bone sample was taken from the bone in contact with the dural attachment of the tumor. Results: This study included 40 consecutive patients who underwent resection for intracranial meningiomas. Radiological evidence of hyperostosis was present in 30 (75) patients. On histopathological examination, tumor invasion of the bone was seen in eight (20) patients. These included seven patients who demonstrated hyperostosis and one patient without hyperostosis. Convexity meningiomas (n=12) showed the highest rate of bony invasion (33.3). Conclusions: A significant number of patients with radiological hyperostosis have tumor invasion of the bone. The authors recommend that one should remove the bone (flap) whenever possible in order to achieve total excision of the tumor and use synthetic material to cover the defect.