Progressive multifocal leukoencephalopathy – report of a case with touch cytology

Progressive multifocal leukoencephalopathy (PML) is an opportunistic demyelinating disease caused by the ubiquitous, usually polyomavirus (DNA virus) belonging to Papovaviridae group. Up to 85% of all cases are associated with HIV. PML is the only known clinical manifestation of JC virus infection. There is lysis of myelin producing oligodendrocytes. Perivascular inflammation is usually absent. Case report We report a case on the basis of clinical features, neuroradiology and brain biopsy/cytology smears. A 34-year-old woman was admitted with a new-onset seizure disorder. On computed tomography, there were right frontoparietal cortex, right external capsule and right basal ganglia lucencies. Core needle biopsy of the radiolucent area revealed foci of white matter demyelination and a few eosinophilic inclusions in oligodendrocytes plus abnormal giant astrocytes, ’Creutzfeldt astrocytes’. Smears showed moderate cellularity, consisting of moderately to markedly atypical cells with enlarged hyperchromatic nuclei. The chromatin pattern showed smudging, with or without clumping, similar in pattern to the human polyomavirus-infected ’decoy’ cells seen in urine cytology. Nuclei were predominantly round to oval, smoothly contoured and often stripped of cytoplasm. Occasional bizarre lobulated or multinucleated forms were seen. Some atypical cells had abundant cytoplasm exhibiting stellate projections. Histologic sections of the biopsy material confirmed the PML diagnosis. The present findings suggest that PML should be considered in the differential diagnosis of marked cytologic atypia in brain aspirates from immunocompromised patients. Positive immunohistochemical staining of oligodendrocytes for JC virus proteins. Conclusion Diagnostic cranial CT-guided FNAB, with cytologic and histologic studies, is extremely valuable in evaluating the nature of central nervous system demyelinated and space-occupying lesions.