MRI of primary CNS lymphoma

The MRI examination in the transverse plane is from a 63-year-old female with primary CNS lymphoma. The T1-weighted sequence (A) reveals a single mass that infiltrates the splenium of corpus callosum (a relatively common location for primary CNS lymphoma; arrow), abutting the third ventricle anteriorly. The mass enhances homogeneously following gadolinium administration (B), is relatively dark on T2-weighted images (C), and reveals restricted diffusion on the diffusion-weighted sequence (bright, D). The reader should note the relative lack of edema on FLAIR studies. These features are consistent with the diagnosis of primary lymphoma of the brain.