Viral Infections

  • Author: Jin S. Suh, MD, FACP (More Info)
  • Editors in Chief: Daniel R. Kuritzkes, MD; Joseph J. Eron, Jr., MD
  • Last Reviewed: 7/26/16 (What's New)


  • Definitive diagnosis of PML is made by brain biopsy, which shows characteristic focal myelin loss with bizarre astrocytes and lipid-laden macrophages
  • Presumptive diagnosis can also be achieved via MRI, which almost always demonstrates distinct white matter lesions in areas of the brain corresponding to the clinical deficits
    • Polymerase chain reaction detection of the JC virus in cerebrospinal fluid can be used to confirm diagnosis

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