70-year-old woman with history of metastatic melanoma status post stereotactic radiosurgery 6 months ago, currently on immunotherapy. In the left cerebellar hemisphere (1001/6), there is a 27 x 26 x 24 mm multilobulated T1 hyperintense mass with surrounding, thick enhancement, particularly along the superior aspect. The central, lobulated portion with high intrinsic T1 signal is stable in size, but the surrounding enhancement has increased in size. Susceptibility artifact corresponding to the lesion represents blood products. Increased T2/FLAIR signal in the white matter of the left cerebellum and vermis has increased from the prior examination. Additionally, there is mass effect on the fourth ventricle and lateral aperture which appears increased from the prior exam. The lateral ventricles appear stable in size and cavum septum is again noted.Encephalomalacia and susceptibility artifact in the right paramedian parietal lobe and left occipital lobe are unchanged. There is a small amount of increased T2/FLAIR signal surrounding these regions.No additional foci of abnormal enhancement are identified. There is no diffusion-weighted abnormality to suspect acute infarct. No extra-axial fluid collections. Several foci of T2/FLAIR hyperintensity are seen in the bilateral subcortical and periventricular white matter, which are nonspecific, but compatible with chronic small vessel ischemic changes. The major intracranial arterial flow-voids are preserved.Sella and orbits are grossly within normal limits. Paranasal sinuses and mastoid cells are clear. Bone marrow signal and extracranial soft tissues are within normal limits.
1.Stable size of left cerebellar hemorrhagic lesion. Given the time course of treatment, increasing edema and thickened rim of enhancement surrounding the lesion are suspicious for tumor progression, however, the possibility of radiation necrosis cannot excluded.2.Slightly increased mass effect with effacement of the fourth ventricle.3.Additional areas of encephalomalacia unchanged. No new intracranial foci of metastasis.