Male, 70 years old, with metastatic renal cell carcinoma, weakness, altered gait and neuropathy. An oval focus of restricted diffusion is seen in the right thalamus measuring up to 13 mm in diameter. In addition, an ill-defined cortically based area of restricted diffusion is also seen affecting the paramedian right occipital lobe. Finally, restricted diffusion affects the entire right hippocampus with sparing of the dentate and parahippocampal gyri. Numerous scattered foci of FLAIR hyperintensity are seen predominantly within the cerebral white matter. There may be at least one tiny chronic cortical infarct in the left occipital lobe. No evidence of significant edema or mass effect is detected. No intracranial hemorrhage or any abnormal extra-axial fluid collections are seen. The ventricles are normal in size and morphology. On postcontrast images, no pathologic parenchymal or extra-axial enhancement is observed. Mucosal thickening is seen in the left maxillary sinus.
1.Areas of restricted diffusion are seen including a relatively well-circumscribed oval in the right thalamus, ill-defined cortical signal in the paramedian right occipital lobe, and specific involvement of the right hippocampus with sparing of the adjacent structures. These lesions could potentially be ischemic in nature. However, the morphology is atypical, particularly the hippocampal involvement. As such, the differential diagnosis would also include an autoimmune or paraneoplastic process, a post-ictal effect, or an atypical infectious process.2.No enhancing lesions are seen to suggest the presence of metastases. No evidence of intracranial hemorrhage is observed. The background brain demonstrates changes which may reflect moderately advanced chronic small vessel ischemic disease.