Recurrent Natural Killer Cell Lymphoma with Central Nervous System Metastasis Mimicking Cerebellar Infarction.

Background: Natural killer cell lymphoma is an uncommon hematologic malignancy, and central nervous system metastasis is rare. The classic magnetic resonance imaging appearance of lymphoma in the brain is T1 hypointense with strong homogeneous gadolinium enhancement, variable T2 signal, and restricted diffusion on diffusion-weighted images. Gadolinium enhancement is an important feature to differentiate lymphoma from infarction.