RESUMO
Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by the JC virus infection and with a frequent lethal outcome. PML usually occurs in immunocompromised subjects, such as HIV-positive individuals, as well as in other conditions characterized by depletion of cellular immunity, including hematological malignancies, autoimmune diseases, and immunomodulatory therapies. We describe the case of a 76-year-old man affected by advanced non-small cell lung cancer who developed PML after six cycles of carboplatin/gemcitabine therapy, during which a transitory leucopenia developed. The patient deceased a few months after the onset of the symptoms. Chemotherapy appears to be uncommon, but definite condition associated to PML.