title: Recurrent Natural Killer Cell Lymphoma with Central Nervous System Metastasis Mimicking Cerebellar Infarction.
abstract: 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.
  
  
  METHODS
  We present the case of a middle-aged man who presented with recurrent natural killer cell lymphoma that metastasized to the cerebellum. Computed tomography and magnetic resonance imaging did not show a contrast-enhancing lesion; imaging features were more suggestive of cerebral infarction. The patient subsequently died, and postmortem examination confirmed natural killer cell lymphoma metastasis to the cerebellum.
  
  
  CONCLUSIONS
  Lymphoma can mimic cerebral infarction on computed tomography and magnetic resonance imaging. An imaging appearance of cerebral infarction in a patient with a history of lymphoma should raise suspicions of lymphoma metastasis.
authors.affiliation: Division of Neurosurgery, Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Lai-fung
authors.initials: LF
authors.lastname: Li
authors.affiliation: Division of Neurosurgery, Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong. Electronic address: gilberto@hkucc.hku.hk.
authors.forename: Gilberto Ka-kit
authors.initials: GK
authors.lastname: Leung
authors.affiliation: Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Ronnie Sin-lun
authors.initials: RS
authors.lastname: Ho
authors.affiliation: Division of Neurosurgery, Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Wai-man
authors.initials: WM
authors.lastname: Lui
mesh_terms: D016543:Central Nervous System Neoplasms / Q000556:secondary* / Q000601:surgery; D002526:Cerebellar Diseases / Q000175:diagnosis*; D002544:Cerebral Infarction / Q000175:diagnosis*; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D019309:Epstein-Barr Virus Nuclear Antigens / Q000032:analysis; D017809:Fatal Outcome; D005682:Gadolinium; D006801:Humans; D007694:Killer Cells, Natural / Q000473:pathology*; D008228:Lymphoma, Non-Hodgkin / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods; D013736:Testicular Neoplasms / Q000473:pathology*
chemical_list: D003287:Contrast Media; D019309:Epstein-Barr Virus Nuclear Antigens; D005682:Gadolinium
keywords: Infarct; Lymphoma; MRI