Progressive multifocal leukoencephalopathy

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Progressive multifocal leukoencephalopathy, abbreviated PML, is a rare neuropathology caused by a polyomavirus.


  • Caused by JC virus (a type of polyomavirus[1]) in the context of immunodeficiency; usu. in the setting of HIV infection.[2]
    • Approximately 5% of HIV patients develop PML.[2]
    • Virus destroys oligodendrocytes -> demyelination results.[3]
  • Suspected cases are biopsied - unlike other demyelinating diseases.[4]


  • Multifocal - as the name suggests.




  • Perivascular inflammatory cells.
  • Foamy histiocytes.
  • Abnormal appearing glial cells:[6]
    • Reactive astrocytes.
    • Oligodendrocytes with nuclear enlargement and glassy magenta chromatin - key feature.
    • Atypical mitoses - known as Creutzfeldt cell.




See also


  1. Berger, JR. (Jun 2011). "The basis for modeling progressive multifocal leukoencephalopathy pathogenesis.". Curr Opin Neurol 24 (3): 262-7. doi:10.1097/WCO.0b013e328346d2a3. PMID 21499097.
  2. 2.0 2.1 Berger, JR. (2003). "Progressive multifocal leukoencephalopathy in acquired immunodeficiency syndrome: explaining the high incidence and disproportionate frequency of the illness relative to other immunosuppressive conditions.". J Neurovirol 9 Suppl 1: 38-41. doi:10.1080/13550280390195261. PMID 12709870.
  3. Mateen, FJ.; Muralidharan, R.; Carone, M.; van de Beek, D.; Harrison, DM.; Aksamit, AJ.; Gould, MS.; Clifford, DB. et al. (Aug 2011). "Progressive multifocal leukoencephalopathy in transplant recipients.". Ann Neurol 70 (2): 305-22. doi:10.1002/ana.22408. PMID 21823157.
  4. URL: Accessed on: 15 January 2012.
  5. URL: Accessed on: 3 January 2012.
  6. 6.0 6.1 URL: Accessed on: 3 January 2012.
  7. URL: Accessed on: 15 January 2012.
  8. Hurley, RA.; Ernst, T.; Khalili, K.; Del Valle, L.; Simone, IL.; Taber, KH. (2003). "Identification of HIV-associated progressive multifocal leukoencephalopathy: magnetic resonance imaging and spectroscopy.". J Neuropsychiatry Clin Neurosci 15 (1): 1-6. PMID 12556565.
  9. Muñoz-Mármol, AM.; Mola, G.; Fernández-Vasalo, A.; Vela, E.; Mate, JL.; Ariza, A. (Nov 2004). "JC virus early protein detection by immunohistochemistry in progressive multifocal leukoencephalopathy: a comparative study with in situ hybridization and polymerase chain reaction.". J Neuropathol Exp Neurol 63 (11): 1124-30. PMID 15581180.