"Pardon My Language": The Curious Case of a Bloody Sandwich and the John Cunningham Virus Reactivation in the Era of Immunomodulatory Drugs

Progressive multifocal leukoencephalopathy (PML) is a rare diagnosis associated with high mortality in different clinical settings. PML has been attributed to the reactivation of the John Cunningham (JC) virus (JCV). JCV typically affects patients with HIV/AIDS, solid organ and hematological malignancies, and those under treatment with immunomodulatory drugs (IMiDs) like pomalidomide. Currently, there are a limited number of reported cases of patients with multiple myeloma (MM) who developed PML reported in the literature, and one case report of a patient with MM diagnosed with PML in association with pomalidomide and daratumumab. Here, we describe a case of PML in a patient with MM status post autologous stem cell transplant (ASCT) on maintenance treatment with pomalidomide who presented with cognitive decline and aphasia. In an era of increased access to immunomodulatory therapies, physicians should be able to recognize this potential complication as discontinuation of the medication could be lifesaving.