Case of the Month
Section Editor: Nicholas Stence, MD
Children's Hospital Colorado, Aurora, CO
August 2021
Next Case of the Month Coming September 7...
Sarcoid-Associated Progressive Multifocal Leukoencephalopathy
- Hospital Course:
- As the CT chest findings were suggestive of pulmonary sarcoid, brain MRI white matter findings were initially thought to be likely related to neurosarcoid, despite the lack of contrast enhancement in the involved white matter changes.
- The patient was treated with a 5-day course of IV methylprednisolone and discharged on methotrexate and infliximab.
- About 2 weeks later, the patient presented to the hospital again with progressive gait instability and new onset of seizures. Brain MRI during the second hospitalization showed worsening nonenhancing white matter lesions with restricted diffusion.
- CSF was positive for John Cunningham (JC) virus and negative for other opportunistic infections.
- The patient was diagnosed with progressive multifocal leukoencephalopathy (PML) during the second hospitalization and immunosuppression was tapered.
- The patient was discharged with a low-dose steroid regimen and in stable condition.
- Discussion:
- Patients with sarcoidosis are vulnerable to PML through a sarcoid-associated, cell-mediated process not directly related to immunosuppression.
- Neurosarcoid is often a misleading diagnosis, delaying the diagnosis of sarcoid-related PML. A retrospective case series and literature review of 30 patients with sarcoidosis-related PML showed approximately 4.5 months of delay in diagnosis, and the fatality rate was 57% with PML.
- Imaging characteristics of PML are multifocal, asymmetric, subcortical white matter lesions that are hypointense on T1-weighted images, hyperintense on T2-weighted images, restrict on diffusion, and do not enhance with contrast. On the other hand, neurosarcoid imaging findings are meningeal/parenchymal enhancing lesions.
- CSF is abnormal in 80% of neurosarcoid but can be normal in PML. Additionally, 38% of patients with PML have a negative JC virus PCR.
- Treatment for neurosarcoid is to increase immunosuppression, whereas treatment for PML is discontinuation of immunosuppression. Due to the polarized management of the 2 diseases, misdiagnosis may lead to worsening of PML. Thus, as lab findings and clinical presentations can be equivocal, imaging characteristics are essential in timely diagnosis and appropriate management of sarcoid-associated PML.
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