A case of progressive multifocal leukoencephalopathy under dimethyl fumarate treatment without severe lymphopenia or immunosenescence

Mult Scler. 2019 Oct;25(12):1682-1685. doi: 10.1177/1352458519852100. Epub 2019 Jun 18.

Abstract

Background: Progressive multifocal leukoencephalopathy (PML) is the main safety concern for dimethyl fumarate (DMF) treatment in persons with multiple sclerosis (pwMS). Risk stratification under DMF is currently based on age above 50 years and prolonged lymphopenia below 500 cells/μL.

Objective: To report a case of PML under DMF without severe lymphopenia or immunosenescence.

Methods: Case report.

Results: A 39-year-old female pwMS developed DMF-associated oligosymptomatic PML. The patient had not experienced any repeated lymphocyte counts below 800 cells/μL and was 15 years younger than previously described cases.

Conclusion: Despite risk stratification, vigilance for PML is advised in all pwMS under DMF. Severe CD8-lymphopenia is a common feature of all published DMF-associated cases.

Keywords: Dimethyl fumarate; lymphopenia; multiple sclerosis; progressive multifocal leukoencephalopathy; risk stratification.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Dimethyl Fumarate / pharmacology*
  • Female
  • Humans
  • Immunosuppressive Agents / pharmacology
  • Leukoencephalopathy, Progressive Multifocal / drug therapy*
  • Lymphocyte Count / methods
  • Lymphocytes / drug effects
  • Lymphopenia / diagnosis
  • Lymphopenia / drug therapy*
  • Multiple Sclerosis / diagnosis
  • Multiple Sclerosis / drug therapy*

Substances

  • Immunosuppressive Agents
  • Dimethyl Fumarate