[Progressive multifocal leukoencephalopathy following azathioprine and steroid treatment of pulmonary sarcoid disease].

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system following reactivation of the John-Cunningham-Virus (JVC) in an immunocompromised host. This rare condition is characterized by rapid progressing neurologic symptoms often leading to death. In the following, we report on a rapid evolving deterioration of mental status due to PML in an 53-year-old man during treatment of pulmonary sarcoid disease using azathioprine and steroids. In contrast to reported lethal outcomes, our patient experienced a slow recovery of his cognitive impairment and later on of his palsy following termination of immunosuppression.