Atypical progressive multifocal leukoencephalopathy with plasma-cell infiltrates

Area of Science:

• Neurology
• Immunology
• Virology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, often fatal, demyelinating disease of the central nervous system.
• Typical PML lesions feature oligodendroglial nuclear inclusions and minimal inflammation.
• Atypical PML presents with infrequent nuclear inclusions, prominent mononuclear infiltrates, and plasma cells within demyelinated lesions.

Purpose of the Study:

• To characterize the clinical and pathological features of atypical progressive multifocal leukoencephalopathy (PML).
• To investigate the role of JC virus and host immune response in atypical PML.
• To compare the neurological outcomes of atypical PML with classic PML.

Main Methods:

• Case report of a 54-year-old male patient with chronic polymyositis on immunosuppressive therapy.
• Histopathological examination of brain lesions.
• Electron microscopy to identify viral particles.
• Immunofluorescence studies using specific antibodies to detect JC virus.

Main Results:

• The patient presented with atypical PML lesions characterized by minimal oligodendroglial nuclear alterations and significant mononuclear inflammatory infiltrates.
• Electron microscopy confirmed the presence of papovavirions within astrocytic nuclei.
• Fluorescent antibody studies identified these viral particles as JC virus.
• The patient's neurological illness was less severe compared to typical PML cases.

Conclusions:

• Atypical PML, while sharing some features with classic PML, exhibits distinct pathological characteristics.
• The presence of JC virus in astrocytic nuclei confirms its etiology in these atypical cases.
• The less devastating neurological course in atypical PML may indicate a more robust host immune response against the virus.
• Further research is warranted to understand the mechanisms of host resistance in atypical PML.