Progressive Multifocal Leukoencephalopathy in Primary Immunodeficiencies

PurposeProgressive multifocal leukoencephalopathy (PML) is a rare but severe demyelinating disease caused by the polyomavirus JC (JCV) in immunocompromised patients. We report a series of patients with primary immune deficiencies (PIDs) who developed PML.MethodsRetrospective observational study including PID patients with PML. Clinical, immunological, imaging features, and outcome are provided for each patient.ResultsEleven unrelated patients with PIDs developed PML. PIDs were characterized by a wide range of syndromic or genetically defined defects, mostly with combined B and T cell impairment. Genetic diagnosis was made in 7 patients. Before the development of PML, 10 patients had recurrent infections, 7 had autoimmune and/or inflammatory manifestations, and 3 had a history of malignancies. Immunologic investigations showed CD4(+) lymphopenia (median 265, range 50-344) in all cases. Six patients received immunosuppressive therapy in the year before PML onset, including prolonged steroid therapy in 3 cases, rituximab in 5 cases, anti-TNF- therapy, and azathioprine in 1 case each. Despite various treatments, all but 1 patient died after a median of 8months following PML diagnosis.ConclusionPML is a rare but fatal complication of PIDs. Many cases are secondary to immunosuppressive therapy warranting careful evaluation before initiation subsequent immunosuppression during PIDs.