Progressive multifocal leukoencephalopathy--incidental finding in the forensic neuropathological examination.

Progressive Multifocal Leukoencephalopathy (PML) is a fatal demyelinating disease of the central nervous system (CNS) caused by the human virus JC (JCV), a small DNA virus which belongs to the subfamily of polyomaviruses. JVC infection is widely extended in the human population in asymptomatic patients; however, in severely immunocompromised patients the virus is able to replicate itself and reach the brain causing PML. It is an extremely rare disease in patients with a competent immune system and few cases have been described in medical literature. We report the case of an elderly immunocompetent man, with no pathological antecedents, who died of sepsis 50 days after suffering extensive and severe flame burns. In the forensic autopsy, a PML was discovered as an incidental finding in the neuropathological examination that was not detected during his time in hospital. Diagnosis was confirmed by the detection of JCV in the brain by in situ hybridization. Possible pathophysiological mechanisms for the reactivation of the JCV and the rapid evolution to the fatal brain demyelinating lesions are discussed. One of the main clinical implications of this case is that immunocompetence should not be considered as an exclusion criterion for the diagnosis of PML.