Progressive multifocal leucoencephalopathy

Progressive multifocal leucoencephalopathy (PML) is a severe, progressive and fatal multifocal demyelinating disease of the brain's white matter.

PML is caused by reactivation of latent JC papova virus. JC virus is a DNA virus of the polyomaviridae family. The virus remains latent in most immunocompetent hosts and rarely presents pathologically. In immunosuppressed hosts, however, a combination of poor cellular response of the host along with reactivation of the virus secondary to recombination of genes results in active disease.

It occurs in association with systemic illness in which cell-mediated and often, humoral immunity is depressed:

• AIDS
• immunosuppressive therapy
• sarcoidosis
• systemic lupus erythematosus
• lymphoma

Features include personality change, dementia, hemiparesis, cortical visual loss, and seizures.

Papova virus is evident in oligodendroglia on electron microscopy. CT and MRI reveal widespread multifocal damage to the white matter. Definitive diagnosis is made by brain biopsy. The virus can be isolated by inoculation on to glial tissue culture.

Antiviral agents have been unsuccessful. Death usually occurs within 3-6 months.

Reference

1. Harypursat V, Zhou Y, Tang S, Chen Y. JC Polyomavirus, progressive multifocal leukoencephalopathy and immune reconstitution inflammatory syndrome: a review. AIDS Res Ther. 2020 Jul 06;17(1):37.