There is a large extra-axial mass with mass effect on the temporal lobe and brainstem. It appears to be arising from the either the posterior aspect of the right cavernous sinus or the right posterior clinoid process and clivus. On the sagittal sequences it has a broad dural attachment. It measures 37 x 33 x 34 mm (LR x AP x SI) and protrudes superiorly and posteriorly. The lesion demonstrates variable signal intensity on T1 and T2 imaging and variable contrast enhancement. Extensive punctate loss of signal on T2 and extensive susceptibility on gradient echo imaging suggests blood products and/or calcium, with the former favoured due to high signal on phase imaging. There is no restricted diffusion. The mass appears separate from the internal carotid artery and the sella. The mass appears separate from Meckel's cave which is displaced laterally and the lower margin of the cisternal trigeminal nerve. The lateral margin of the lesion effaces the right medial temporal lobe. The posterior margin displaces the upper pons, midbrain and cerebral peduncle posteriorly and medially. There is however no temporal lobe or brain stem oedema.
No other mass lesion. The remainder of the brain is normal. No evidence of demyelination.
Conclusion
Large right extra-axial mass probably centred on the posterior right cavernous sinus. The lesion is not typical for any single pathology and hence carries a differential diagnosis of atypical meningioma, atypical trigeminal schwannoma, haemangiomapericytoma or cavernous haemangioma. Alternative less likely diagnoses, as the lesion shows some features of a chondroid lesion, is a chondroma or chondrosarcoma of the clivus and right posterior clinoid process.
Further assessment with CT and CTA is advised to A) assess for osseous involvement and B) confirm the relationship with the ICA.