Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Primary CNS lymphoma accounts for 2-3% of all of brain tumors. Most of the primary CNS lymphomas are diffuse large B‑cell lymphomas. Although there is a strong association with immunocompromised patients, it can also occur in immunocompetent older individuals. Characteristically, the lesions are solitary with periventricular in location. Although appearing intraventricular in axial slices this lesion is located in the splenium and posterior part of the body of the corpus callosum. The typical MRI features are T2 iso/hypointensity (A, arrow), T1 hypointensity (B, arrow), vivid homogenous enhancement (C, arrow) and restricted diffusion (quiz images).