Large heterogeneous frontal mass, associated with the inferior falx with at least a large component being extra-axial in location (CSF cleft, peripheral vessels and buckling of adjacent cortex). This is not, however, true around the entirety of the mass, and an exophytic parenchymal tumour remains a possibility.
Large, central, lobulated solid component enhances heterogeneously and contains regions of susceptibility artefact. Peripherally enhancing cystic/ necrotic components contain fluid levels with susceptibility artefact in keeping with blood product. Further peritumoral cysts demonstrate incomplete FLAIR suppression.
Marked mass effect with near complete effacement of the anterior horns of the lateral ventricles, focal inferior buckling of the corpus callosum anteriorly, and partial effacement of the third ventricle and suprasellar cistern. Posterior fossa CSF spaces remain intact. MRS demonstrates elevated choline, and probable glutamine/glutamate as well as lipid-lactate peaks. NAA is, importantly, present as is creatine. Cerebral blood volume is elevated. Moderate diffusion restriction (~1000 x 10^-6 cm^2/s). Allowing for artefact, major dural venous sinuses including the superior sagittal sinus appear to enhance normally. No bony abnormality is seen.
Conclusion: Large, heterogeneous frontal mass has a large extra-axial component, but not definitely entirely extra-axial. Although at first a meningioma, or perhaps a hemangiopericytoma, were the favoured diagnoses, the presence of tumoral haemorrhage and moderate NAA on MRS makes this unlikely. The differential, therefore, includes an exophytic parenchymal/cortical tumour such as a pilocytic astrocytoma, pleomorphic xanthoastrocytoma, ganglioglioma or even parenchymal ependymoma. This is very unlikely to represent a high-grade diffuse glioma.