Revision of PML Diagnostic Criteria

Dear Colleagues,

Almost ten years ago consensus criteria for the diagnosis of progressive multifocal leukoencephalopathy (PML) were published by the Neuroinfectious Disease Section of the American Academy of Neurology (AAN). These diagnostic criteria provide two approaches for diagnosis: the first based on histopathological features coupled with detection of the causative agent, the JC virus (JCV); the second, by the presence of defined radiographic and clinical features coupled with detection of JCV DNA in the CSF. Over the past decade the 2013 consensus criteria have been widely applied and have greatly facilitated an accurate diagnosis of PML. However, PML remains a challenging diagnosis in certain clinical settings.

Advancements in the field, including an increased familiarity with less typical clinical presentations of JCV infection as well as the development of biomarkers able to identify the earliest or even preclinical stages of the disease, prompted the establishment of an international, multidisciplinary panel tasked with critical review of the 2013 consensus criteria.  The International Panel on PML Diagnosis aims to update and expand PML case definitions so as to account for the full expression of this infection as well as to update the current diagnostic algorithm as needed so as to support best patient management, optimize outcomes and reduce practice variation. The panel will further identify gaps in current literature as areas for future research.

On this website, you will find posted for public comment the panel’s proposed research protocol. Your comments and suggestions are highly appreciated.

Please click on this link to view the study protocol

Expanded Diagnostic Criteria and Phenotypic Classification Related Disease

Please click on this link to view the Data Extraction Forms and the Qualitiy Assessment Form

Histopathological Data Extraction Form (pdf)

Clinical and Biomarker Data Extraction Form (pdf)

Imaging Data Extraction Form (pdf)

Qualitiy Assessment Form (pdf)

Many thanks for sharing your view and expertise on this project.

Please fill out this form  (PML Diagnostic Criteria Review Form), save and send attached to: or

Yours sincerely,


Irene Cortese MD PhD                   Mike P. Wattjes MD PhD


On behalf of the International Panel on PML Diagnosis