Presentation
Altered mental status in a known HIV-positive patient.
Patient Data
There is confluent, somewhat symmetric, multifocal, frontal and parieto-occipital periventricular and sub-cortical demyelination. There is brainstem involvement additionally (especially midbrain and pons). The cerebellar hemispheres are spared. There is no mass effect, no perilesional edema, negative diffusion and ADC mapping and no abnormal enhancement. There is no optic neuritis. MRI brain is otherwise normal.
Non-enhancing and non-necrotic anterior and posterior cervical chain lymphadenopathy are consistent with the known HIV status (best appreciated on sagittal imaging). In addition the heterogeneous parotid gland appearance allude to HIV and benign lymphoepithelial lesions.
(Axial T1 pre contrast is unavailable).
There are scattered, small and punctate, non-specific, high signal intensity foci on T2 and FLAIR imaging with the periventricular deep white matter and subcortical regions. These are supratentorial with sparing of the brain stem and posterior fossa. There is an absence of any callososeptal involvement, no mass effect, and no abnormal enhancement. Diffusion imaging is negative, (ADC mapping is unavailable)
Incidental uncomplicated, chronic, left maxillary antral sinusitis.
Case Discussion
In a patient with known HIV and the above imaging features, the differential diagnosis mainly includes HIV encephalopathy and PML. The wider differential diagnosis includes multiple sclerosis, PRES, ADEM, and primary CNS lymphoma, all appearing unlikely based on the given history, imaging features above and CSF confirmation of positive PCR for the JC virus suggesting PML. The CSF was otherwise unremarkable and negative for all other infections. The patient had a low CD4 count of 139 cells/uL.
There is typical subcortical U-fiber involvement. The symmetric pattern is unusual in PML, but this is seen in our local experience and especially in advanced disease when the areas of confluent demyelination "merge". In this instance, there is an absence of basal ganglia, thalamic and cerebellar involvement.
On PACS review, the initial scan was found and demonstrated scattered small and punctate high signal intensity foci on T2 and T2 FLAIR imaging. These are non-specific in nature. At this stage, It would have been challenging to suggest PML. The HIV status was also unknown at the time of presentation.
This case highlights progressive demyelination in HIV in the absence of anti-retroviral therapy (refusal/poor compliance) over a period of 16 months.
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