PML in a Patient without Severe Lymphocytopenia Receiving Dimethyl Fumarate

New England Journal of Medicine 372(15):1474 (2015) PMID 25853764

Progressive multifocal leukoencephalopathy developed in a 64-year-old woman who was treated with compounded dimethyl fumarate for psoriasis. Lymphocytopenia in this patient was not as severe as in other patients with PML receiving fumaric acid esters. To the Editor: Fumaric acid esters, which are prescribed for the treatment of psoriasis and multiple sclerosis, are considered to have a favorable risk profile. However, treatment-related progressive multifocal leukoencephalopathy (PML) has been described in association with long-lasting, severe lymphocytopenia (<500 lymphocytes per cubic millimeter).1–3 This has led to the recommendation that lymphocyte counts should be monitored in patients receiving these drugs in order to prevent opportunistic infections such as PML.4 Here, we report a case of fatal PML after treatment with compounded dimethyl fumarate (DMF) in a patient without severe lymphocytopenia. On July 18, 2014, a 64-year-old woman . . .

DOI: 10.1056/NEJMc1413724