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Atypical progressive multifocal leukoencephalopathy with plasma-cell infiltrates
Abstract:
In rare cases of progressive multifocal leukoencephalopathy (PML) the lesions are atypical in that the characteristic alteration of oligodendrocytic nuclei is infrequent or absent, and the demyelinated foci contain mononuclear inflammatory infiltrates including numerous plasma cells. Otherwise these cases, both as to the topographic features of the lesions, and the background of chronic lymphoproliferative or myeloproliferative disease or immunosuppressive treatment, conform to the usual pattern. In the case here reported, that of a 54-year-old man receiving immunosuppressive drugs for chronic polymyositis, electron microscopy showed papovavirions in astrocytic nuclei and fluorescent antibody studies indicated that these represented JC virus. In this and the 3 previously reported similar cases of atypical PML, the neurologic illness was less devastating than generally occurs in classic PML. Possibly these cases represent instances of unusually strong host-resistance against the disease.
Insights
Atypical progressive multifocal leukoencephalopathy (PML) cases show less severe neurological illness. This suggests a stronger host immune response against JC virus in these rare instances.
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.