Low grade astrocytoma causing dural and calvarial destruction.

This case report describes destruction of overlying dura and calvaria by a low grade glioma in the absence of prior surgery or radiation. Bone and dural involving is known to occur with some malignant tumors, but due to low grade glioma is very rare. The initial radiologic examinations demonstrated a heterogeneous mass in the right parietal region with both extra- and intra-axial components. No inward displacement of the adjacent dura was observed. Initial consideration for extra-axial lesions includes metastatic lesions, lymphoma, or an aggressive meningioma. The pathologic findings demonstrated a glial cell origin. To our knowledge, destruction of the dura and calvaria from a low-grade glioma, without prior surgery or radiation, has not been well documented previously. Calvarial destruction with associated intra-axial lesions on imaging may prompt the diagnosis of extra-axial tumors such as aggressive meningiomas, metastasis and lymphoma. We report an unusual case of parietal low-grade glioma with destruction of the dura and calvaria in the absence of prior surgery or radiation. The erosion probably is due to pressure atrophy of the dura and inner table and thinning of the diploe. The mechanism of skull erosion in these superficial gliomas relates to their chronic mass effect (8). The mass displaces the CSF, which normally cushions and diffuses brain pulsations over a wide area. Once the CSF space is effaced, the brain may directly transmit these pulsations to the inner table. Over time, this localized elevated pressure may erode the cortical bone of the inner table.