A rare case of progressive multifocal leukoencephalopathy

Area of Science:

• Neuroscience
• Infectious Diseases
• Radiology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, opportunistic CNS demyelinating disease caused by John Cunningham (JC) virus reactivation, primarily affecting immunocompromised individuals.
• Typical PML lesions are found in subcortical white matter, but involvement of the brainstem and anterior corpus callosum is uncommon.
• Human immunodeficiency virus (HIV) infection significantly increases the risk of PML due to immune deficiency.

Observation:

• A 40-year-old female with inadequately treated HIV presented with a tonic seizure and confusion.
• Workup revealed low CD4 and CD3 counts, transaminitis, and an abnormal EEG.
• Brain imaging (CT and MRI) demonstrated subcortical and periventricular white matter lesions extending into the brainstem and anterior corpus callosum.

Findings:

• The case illustrates characteristic PML imaging features in the context of advanced HIV, including white matter lesions crossing the anterior corpus callosum (not the posterior splenium, differentiating from the 'barbell' sign).
• Lesions extended inferiorly along the corticospinal tract into the midbrain and pons, a rare concomitant occurrence.
• JC virus reactivation was presumed to be the cause, given the clinical and imaging findings in an immunocompromised host.

Implications:

• This case emphasizes the importance of recognizing atypical PML presentations, particularly in immunocompromised patients with HIV.
• Understanding these specific imaging patterns, such as anterior corpus callosum involvement and corticospinal tract extension, aids in early diagnosis and management.
• Prompt diagnosis and initiation of appropriate HIV therapy and supportive care are crucial for managing PML and improving patient outcomes.