Progressive multifocal leukoencephalopathy in patients with sarcoidosis.

Objective: To describe characteristics, risk factors, and treatment outcome of progressive multifocal leukoencephalopathy (PML) complicating sarcoidosis.
Methods: A retrospective chart and literature review was performed. Patients were identified through records from physicians of the Groupe Sarcoïdose Francophone. Each case was compared with 3 controls.
Results: Ten cases were found (8 men). The median age at sarcoidosis diagnosis was 34.9 (±6) years. PML and sarcoidosis were diagnosed concomitantly in 2 cases, while sarcoidosis was previously known in 8 cases, including 7 cases treated with steroids (mean time between sarcoidosis diagnosis and PML was 114 [±99] months). The mean CD4 cell count was 215 (±139)/mm(3). Neurosarcoidosis was thought to be the problem in 8 cases and treatment was intensified, delaying PML diagnosis by 4.5 (±3.9) months. Eight patients received PML-specific treatment. On the whole, 6 patients died of PML within a mean time of 8 (±4.3) months. Patients with PML were significantly younger than controls. When combining our 10 patients with another 20 from the literature, we found that 17 patients (57%) died from sarcoidosis-associated PML; thus, the fatality rate was 57%.
Conclusions: PML during sarcoidosis is often misdiagnosed. It is not associated with severe CD4 lymphocytopenia. Fatality rate is high in comparison with PML associated with other conditions. Interrupting immunosuppression remains the mainstay of treatment.