Cortical demyelination in PML and MS: Similarities and differences

Area of Science:

• Neuropathology
• Neuroimmunology
• Infectious Neurology

Background:

• Multiple sclerosis (MS) and progressive multifocal leukoencephalopathy (PML) are demyelinating diseases affecting the central nervous system.
• Cortical involvement is increasingly recognized in MS, but its characteristics in PML are less understood.

Purpose of the Study:

• To characterize and compare the pathological changes in the cerebral cortex of patients with PML and MS.
• To investigate the distribution, inflammatory activity, and neuritic pathology of cortical lesions in PML and MS.

Main Methods:

• Autopsy brain tissue analysis from patients with PML, MS, and controls.
• Immunohistochemistry for myelin, inflammatory cells, and neurofilaments.
• Confocal microscopy to examine neuritic pathology in PML cortical lesions.

Main Results:

• MS brain tissue showed leukocortical, intracortical, and subpial cortical demyelination.
• PML brain tissue exhibited intracortical and leukocortical lesions, but not subpial.
• Cortical lesions in both PML and MS had reduced inflammatory cells compared to white matter lesions.
• Neuritic pathology, including dystrophic and transected neurites, was observed in PML cortical lesions, similar to MS.

Conclusions:

• Cortical pathology is a distinct characteristic of PML.
• Comparing cortical pathology in PML and MS provides insights into the pathogenesis of both diseases.