Progressive MultifocalLeucoencephalopathy (PML): Possibility of Morphological Diagnosis byClassic Methods and In Situ Hybridisation

Overview

Progressive multifocal leucoencephalopathy is caused by infection with JC virus. The diseaseaffects patients with immunodeficiencies, hematologic diseases, and patients treated with radio-therapy. The disease is characterised by foci of demyelinisation with atypical astrocytes andoligodendrocytes. Oligodendrocytes contain typical intranuclear inclusions. Progressive multifo-cal leucoencephalopathy and its verification is presented in three cases. Two patients died ofprogression of a malignant neoplasm and the leucoencephalopathy was a complication of themalignancy. The third case was a biopsy specimen taken from the brain of a patient who receiveda renal transplant. The material of all patients was analysed by light and electron microscopy,and in situ hybridisation with a probe specific for JC virus. In situ hybridisation proved to be themost specific and a simple method to demonstrate the infection in all cases. It is useful in instan-ces in which the histologically detectable lesion is not characteristic, and in cells in which theconventional histologic methods fail to reveal the intranuclear inclusions of JC virus.

Key words:
progressive multifocal leucoencephalopathy - in situ hybridisation