[The phenomenon of pseudotumorous cross immunohistochemical reactivity of glia in progressive multifocal leukoencephalopathy]. / Fenomen psevdotumoroznoi perekrestnoi immunogistokhimicheskoi reaktivnosti glii pri progressiruyushchei mul'tifokal'noi leikoentsefalopatii.

Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating brain damage caused by infection of oligodendrocytes and astrocytes with the lytic JC virus on the background of immunosuppression. A case report of PML with a tumor-like course is presented. Morphological diagnostics revealed non-specific staining of antibodies to Ki-67, p53, IDH1, NF and Vim in the nuclei of gliocytes affected by the JC virus. Histological examination and microscopic evaluation of the changes in the brain for the diagnosis of PML is a priority. The recommended intravital biopsy does not always help in clear verification of PML due to the limited volume of tissue fragments presented for research. For the correct interpretation of changes during an intravital pathological examination and verification of PML, it is important to take material during a stereotaxic biopsy, not only from the center, but from the edges and perifocal zone of the altered tissues for the possibility of a spatial histological assessment of the pathological process.