Lymphoma

54 year old woman who presented with progressive left sided weakness and left facial droop. Imaging demonstrates multiple T2 hypointense, enhancing lesions which demonstrate restricted diffusion compatible with hypercellularity. Findings are most compatible with CNS lymphoma with the T2 hypointensity being particularly characteristic of this lesion. Predisposing factors include a history of HIV, EBV infection, or post transplant status (PTLD). The majority are iso to hypointense on T2, enhancement and diffusion restriction is variable. If low grade, surgery may be effective. Otherwise, treatment is with steroids and chemotherapy with or without radiation. The differential for this appearance includes metastasis.