ABSTRACT
Background: Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral demyelinating infectious disease of the central nervous system (CNS) which is rare & fetal. There is various clinical presenting symptoms for the disease. Case presentation: This paper presents a clinical case of PML in a patient with B-CLL in remission, previously treated with Chlorambucil that complicated later in disease course with Covid-19 and mucormycosis. Conclusion: like many other viruses, the more relevant immune-competent cells in host defense against JCV, appear to be T cells. This issue is recently also suggested in Covid 19 patients which a dissociation between severity and seroconversion has been reported. The case reported due to its rarity and multiple challenges in its diagnosis and treatment.