Progressive multifocal leukoencephalopathy in two psoriasis patients treated with efalizumab.

Progressive multifocal leukoencephalopathy (PML) is a rare neurological disorder that occurs almost exclusively in immunocompromised individuals by reactivation of the John Cunningham virus (JC virus), a polyomavirus found latent in more than 80 percent of healthy adults. Efalizumab, an immunosuppressive monoclonal antibody targeting T cells, has been used for treatment of moderate-to-severe chronic psoriasis. The authors describe two cases of PML that occurred in patients < or = 70 years old treated with efalizumab for more than three years. Both presented with symptoms resembling cerebral infarction (slurred speech, reduced motor control, personality changes) and were assessed for evidence of stroke. Multiple magnetic resonance images over successive weeks demonstrated progression of cerebral abnormalities. PML was diagnosed, and the presence of JC virus was confirmed in spinal fluid samples. Both patients died shortly after diagnosis. Dermatologists treating patients with immunosuppressive agents should be alert for the symptoms of PML and seek immediate consultation with a neurologist should symptoms arise.