Inflammatory progressive multifocal leukoencephalopathy in human immunodeficiency virus-negative patients

Objective: Inflammatory progressive multifocal leukoencephalopathy (iPML) with enhancing magnetic resonance imaging (MRI) lesions and leukocyte infiltration occurs in human immunodeficiency virus (HIV)-infected individuals after highly active antiretroviral therapy (HAART) treatment. MRI diagnostic criteria for PML suggest that iPML does not occur in HIV-negative individuals. Methods: We studied pathologically proved PML (12 by biopsy, 9 with MRI, 32 at autopsy). Results: HIV-negative (2/5) and -positive (2/4) PML patients had enhancing MRI lesions, correlated with CD3(+) lymphocyte infiltration. Inflammatory infiltrates occurred in the majority of HIV-negative (7/8) and HIV-positive/HAART (17/20) cases (p > 0.2), but in only 2 of 16 HIV-positive/non-HAART cases (p < 0.001). Interpretation: iPML showed radiographic and pathological similarity in HIV-positive/HAART and HIV-negative patients. HIV-negative iPML necessitates further consideration of MRI criteria for PML.