A Radiological- Pathological Correlation of Hyperostosis Among Patients With Intracranial Meningiomas at the Kenyatta National Hospital

Abstract

Background: Meningiomas account for 34.4% of all central nervous system (CNS) neoplasms in Kenya. Hyperostosis has been described in 25% to 44% of meningiomas. The risk of tumor recurrence is largely dependent on the extent of resection. According to Simpson et al, complete bony removal is associated with a 9% recurrence rate over a ten year period. Prior traumatic injury, irritation of bony elements by the tumorous growth without bony invasion, activation of osteoblastic cells in healthy bone by substances produced by neoplastic cells, synthesis of bone fragments by the tumor itself, and vascular abnormalities brought on by the neoplasm are all factors that may contribute to hyperostosis. The purpose of this study was to ascertain whether radiological changes in skull bones observed in cases of meningiomas are solely attributed to tumor invasion. Study design: This was a prospective cohort study. Broad objective: To determine the proportion of patients with radiologic hyperostosis who have microscopic tumor invasion in bone . Study area: Kenyatta National Hospital Neurosurgery and Pathology departments. Study population: Post-surgical patients who underwent resection of meningiomas. Materials and methods: This prospective study included all patients with a diagnosis of meningioma with radiological evidence of hyperostosis. Preoperatively, a computed tomography (CT) scan was done by a consultant radiologist in all patients and reviewed by two neurosurgeons for associated bony hyperostosis. Intra-op, a sample of the bone measuring 2cm by 2cm by 2cm displaying features of hyperostosis was harvested. Bone samples were decalcified with 10% formic acid. A consultant neuropathologist thereafter microscopically evaluated the samples to check for bone invasion. Results: A total of 36 patients underwent resection for intracranial meningiomas during the study period. Radiological evidence of hyperostosis was present in 22 (61.1%) xvi patients. Out of the 22 patients, female patients were 17(77.3%) while male patients were 5(22.7%). The median age of the patients at the time of surgery was 45.5 years (range 20-65 years; mean 44.3 ± 11.9 years). On histopathological examination, Meningothelial meningioma was the most common variant (68.2%). Microscopic tumor invasion of the bone was seen in 13 (59.1%) patients. Conclusion: A significant number of patients with radiological hyperostosis had tumor invasion of the bone. The findings of this study show that one should remove the bone flap whenever possible in order to achieve total excision of the tumor, reduce recurrence rates and perform titanium mesh/ hydroxypartite cement cranioplasty for calvarial reconstruction.