Progressive multifocal leukoencephalopathy.

Three cases of progressive multifocal leukoencephalopathy have occurred in one hospital in a 3-year period. The 3 patients had been receiving chemotherapy for chronic myeloid leukaemia, lymphocytic lymphoma and acute myeloid leukaemia respectively, and developed progressive neurological illnesses which resulted in their deaths. The routine neurological investigations were unhelpful and although the diagnosis was suspected in 2 cases, treatment was not given. It is felt that the disease is not as rare as originally believed and that brain biopsy should be more readily considered since progressive multifocal leukoencephalopathy is potentially treatable.