CD4 count was noted to be very low. Patient was started on antiretroviral therapy (ART).

Biopsy - infiltration by mononuclear cells including lymphocytes, microglia, histiocytes and plasma cells.  Associated gliosis as well as scattered astrocytes and oligodendrocytes with 'ground-glass' nuclear change. There is evidence of myelin degeneration. Many vessels show vasculitic changes.

The inflammatory infiltrate consists predominantly of CD2+/Cd3+ T-cells with moderate numbers of CD20+ B-cells. Appearances are consistent with PML with associated IRIS.