An infectious disease specialist is reviewing brain magnetic resonance imaging (MRI) scans for several patients with advanced HIV infection (CD4+ T-cell count < 50/mm³). Each patient presents with new-onset focal neurological deficits or altered mental status. Match each specific MRI finding with its most likely underlying etiology.
- Multiple contrast-enhancing ring lesions with surrounding edema, predominantly located in the basal ganglia and at the gray-white matter junction.Toxoplasma gondii encephalitis
- A solitary, homogeneously enhancing periventricular mass with subependymal spread.Primary central nervous system lymphoma
- Multiple, asymmetric, non-enhancing hyperintensities in the subcortical white matter without associated mass effect or edema.Progressive multifocal leukoencephalopathy
- Clustered, non-enhancing cystic lesions in the basal ganglia and thalami representing dilated perivascular spaces.Cryptococcal meningoencephalitis
Answer
Multiple ring-enhancing lesions correspond to Toxoplasma encephalitis; a solitary periventricular mass corresponds to Primary CNS lymphoma; non-enhancing white matter lesions without mass effect correspond to Progressive multifocal leukoencephalopathy; and non-enhancing cystic lesions in the basal ganglia correspond to Cryptococcal meningoencephalitis.
Accurate interpretation of brain MRI findings in patients with advanced HIV is a critical diagnostic skill. The varied presentations—ring enhancement versus non-enhancement, single versus multiple lesions, and presence versus absence of mass effect—serve as primary discriminators between toxoplasmosis, primary CNS lymphoma, PML, and cryptococcal disease.
Step-by-Step Solution
Key Concept
Neuroimaging patterns of opportunistic central nervous system infections and malignancies in advanced HIV