[Progressive multifocal encephalitis (PML)].

In four cases of progressive multifocal leucoencephalitis the basic disease was always a malignant lymphogranuloma. Changes in the brain were multifocal, however the frontoparietal area of the white matter was affected most frequently and foci in this part were oldest. In these foci demyelination with atypical astrogliosis predominated, and there was a very small number of scavenger cells. At the periphery of foci always proliferation and enlargement of homogenous oligodendroglia nuclei were found sometimes with inclusions which in immunoassay sometimes had a common antigen with papovirus SV 40 and on electronoptic examination always contained many virions of the papovirus. No direct relationship was found between the duration of the neoplastic process, its type and changes in the CNS.