STEREOTAXIC BRAIN BIOPSY FOR DIAGNOSIS OF PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY

We describe three patients in whom the diagnosis of progressive multif ocal leukoencephalopathy (PML) was made by stereotactic biopsy. All th ree patients had a rapidly progressive clinical course pathologically characterized by demyelination, Alzheimer I astrocytes, and basophilic intranuclear inclusions in oligodendrocytes. In each case, the diagno sis was confirmed with immunohistochemical staining of oligodendrocyte s for the JC virus and in one case by electron microscopy. Determinati on of the adequacy of tissue received at the time of frozen section is critical and can direct the appropriate submission of tissue to maxim ize available diagnostic procedures.