Pathomorphological variations of the AIDS-associated progressive multifocal leukoencephalopathy.

Area of Science:

• Neuropathology
• Infectious Diseases
• Immunology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease affecting the central nervous system.
• PML is caused by the JC virus and primarily occurs in immunocompromised individuals, notably those with acquired immune deficiency syndrome (AIDS).
• Understanding the pathological spectrum of PML in AIDS patients is crucial for diagnosis and management.

Purpose of the Study:

• To present a pathological analysis of 20 cases of PML in AIDS patients.
• To distinguish between early, atypical, and severe forms of PML based on pathomorphological and clinical features.
• To discuss the differences in PML pathology between AIDS and non-AIDS cases.

Main Methods:

• Pathological analysis of 20 PML cases in AIDS patients diagnosed between 1987 and 1999.
• Evaluation of demyelination, glial pathology (oligodendrocytes, astrocytes), and inflammatory infiltrates (macrophages, lymphocytes).
• Assessment of lesion distribution and severity, including cavitation and topographic prevalence.

Main Results:

• PML occurred in 10% of the studied AIDS cases.
• Three forms were identified: early (widespread, moderate demyelination, oligodendroglial focus), atypical (unifocal changes), and severe (intense demyelination, tissue destruction, cavitation, significant inflammation).
• Severe forms showed topographic prevalence to either brain hemispheres or cerebellum, suggesting a potential 'cerebellar form'.

Conclusions:

• PML in AIDS patients exhibits diverse pathological presentations.
• Distinguishing between early, atypical, and severe forms aids in understanding disease progression.
• The frequent cerebellar involvement in AIDS-related PML warrants consideration for a distinct cerebellar form.