These findings are non-specific, but in an HIV+ patient, PML is not excluded. The main differential diagnosis would be HIV encephalitis, CMV encephalitis, IRIS (Immune Reconstitution Inflammatory Syndrome), ADEM & multiple sclerosis.

This case is atypical as the findings are not as extensive as expected in PML. The patient died a few months later. This patient had a prior brain biopsy which confirmed JC virus-infected oligodendrocytes with enlarged amphophilic nuclei located at the periphery of the lesions.

Other pathologic findings include :

• reactive gliosis with enlarged astrocytes
• macrophages containing phagocytosed cellular debris and myelin​​