Multifocal Necrotizing Leukoencephalopathy Mimicking Sporadic Creutzfeldt-Jakob Disease

denced a decerebrate coma with preserved brainstem reflexes. Diffuse PSWC were evident upon EEG recording ( fig. 1 ). In spite of sodium correction, valproate administration and supportive therapy, no clinical or EEG improvement was observed. The CSF 14-3-3 protein test was positive, and tau concentration was raised (5,080 pg/ml). Brain MRI showed mildly high DWI signals involving the left parietal cortex (not shown). PRNP gene analysis disclosed a 129 VV genotype with no mutations. A diagnosis of clinically probable sporadic CJD was made. Tau concentration had risen to 10,480 pg/ml when a second CSF sample was drawn 4 weeks later. The patient died after 2 months from multiple organ failure. Because of suspected CJD, postmortem analysis was limited to the intracranial content. On eosin-hematoxylinstained sections, typical lesions of prion diseases (spongiosis, gliosis, and neuron loss) were absent. Furthermore, Western blot and immunohistochemistry studies failed to detect the pathologic prion protein. Therefore, a CJD diagnosis was ruled out. Instead, disseminated foci of vacuolation were evident in the transverse tracts of the basis pontis and were associated with scattered axonal swellings and activated macrophages ( fig. 2 ). Rare foci of vacuolation were present also at the supratentorial level (not shown). A pathological diagnosis of MNL was made. Dear Sir, Creutzfeldt-Jakob disease (CJD) is a prion encephalopathy characterized by rapidly progressive dementia, myoclonus and various neurological symptoms. The diagnosis is supported by a typical EEG pattern with periodic spike-wave complexes (PSWC) and/or a positive CSF 14-33 protein test [1] . Additionally, raised CSF tau levels ( 1 1,300 pg/ml) and certain MRI aspects – i.e. high diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery signals involving deep nuclei and the cerebral cortex – have been shown to be useful in the diagnostic work-up of prion diseases [2, 3] . Multifocal necrotizing leukoencephalopathy (MNL) is an uncommon clinicopathological entity usually diagnosed in immune-suppressed patients and characterized by multiple foci of vacuolation at the basis pontis and, less frequently, at the supratentorial level [4] . Here we describe an MNL patient mimicking sporadic CJD in its whole clinical, EEG, MRI and CSF aspects.