Figure 7. (a) An axial T2W image in an HIV positive male shows abnormal signal in the left cerebellar peduncle extending into the pons. This rapidly progressed. The coronal T1W image after contrast (b) did not show significant enhancement and the concern was whether this might be lymphoma rather than progressive multifocal leucoencephalopathy. (c) The FDG-PET scan shows no significant uptake, indicating that progressive multifocal leucoencephalopathy was more likely. This was confirmed by biopsy.