Osteoma of the inner table of the skull - CT diagnosis

AIM: The purpose of this study was to ascertain CT criteria for the differentiation of osteoma of the internal table of the skull (OIT) from meningioma, MATERIAL AND METHODS: Thirty-eight patients with proven OIT by operation or by postmortem examination and 100 patients with proven meningioma were studied. RESULTS: Unenhanced computed tomography (UCT) and enhanced CT (ECT) was performed in each case and images on brain and bone window settings were evaluated. Measurements were taken of the widest and narrowest diameters of the OIT on the bone,window images, The OPT appeared as an ivory-density, mushroom-like mass with well-defined borders attached to the inner table of the skull by a bony stalk or neck. The ratio between the widest diameter of the mass and the narrowest area of the stalk or neck ranged from 1.6 to 6, The CT features of 100 meningiomas were not consistent with OIT, using the following parameters: contrast enhancement, surrounding vasogenic oedema, dural lucent line, osteolytic bone lesion and cystic component, Hard meningiomas without contrast enhancement did not present with a bony stalk or neck. No meningioma had the CT features of OIT, and no OIT had the CT features of meningioma, No patient operated on for OIT showed any clinical improvement following surgery, CONCLUSIONS: Computed tomography examination can be sufficient for the diagnosis of OIT and may therefore prevent unnecessary surgery. (C) 2000 The Royal College of Radiologists.