18 May 2011

PML - Progressive Multifocal Leukoencephalopathy

Immunocompromised patient after bone marrow transplant with progressively deteriorating neurological symptoms. MRI investigations show within two weeks progressive diffuse white matter changes that did not enhance and initially shown some degree of diffusion restriction. Laboratory study of the Cerebro Spinal Fluid (CSF) has proven JC virus markers. This is a case of Progressive Multifocal Leukoencephalopathy (PML) that is caused by JC virus infecting oligodendrocytes and causing rapidly progressive demyelination in immunocompromised patients. It characteristically involves subcortical U-fibers. See frontal lobe on the transversal T2.
It is also known to affect Multiple Sclerosis (MS) patients treated with Natalizumab (Tysabri). Therefore we often screen our MS patients receiving Tysabri and developing neurological symptoms for possible PML.
Radiologically it is not an easy diagnose. Look at progressive confluent non-enhancing white matter changes that have predilection to subcortical regions but also in basal ganglia and infratentorial.
You might also check my previous case of Progressive Multifocal Leukoencephalopathy - PML.