Noon Report: Brain Lesion in HIV/AIDS

This week we had the Yellow team present a patient with HIV/AIDS who came to the hospital with a dizziness and was found to have a brain lesion. Lets discuss the workup and differential diagnosis for brain lesions in a patient with AIDS.

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CNS lesions in patients with HIV/AIDS can be due to vascular, viral, bacterial, fungal, parasitic, and neoplastic causes. When a patient with HIV presents with a brain lesion, further information including the patient’s adherence to antiretroviral therapy, CD4 count, and social history can help narrow the differential. Here is a break down for each etiology:

MRI showing primary CNS lymphoma [2]

• Vascular – Patients with HIV/AIDS can have strokes with symptoms that correlate to the area of injury. Strokes may be a sequelae related to one of the conditions below.
• Viral – CMV encephalitis, progressive multifocal leukoencephalopathy (PML), and HIV itself are the most common. CMV in the CNS most often involves polyradiculitis and periventriculitis though mass lesions and abscesses can occur. PCR for CMV in the CSF carries an 86% PPV and 97% NPV. PML is due to reactivation of JC virus and results in a demyelinating condition. Presentation of PML is often subacute with focal deficits and cognitive decline.
• Bacterial – Depending on the degree of immunosuppression and co-morbidities, HIV/AIDS patients are at risk for a multitude of bacterial infections that affect the CNS. Cerebral abscess of staph aureus can occur. These patients classically have concurrent staph aureus bacteremia, a history of IVDU, and a toxic appearance with fever and sepsis. Tuberculosis can rarely present with tuberculomas that appear as multiple, small, ring-enhancing lesions on imaging.
• Fungal – The majority of fungal infections present as meningitis as opposed to brain lesions. Rarely HIV/AIDS patient can have cryptococcomas, histoplasomas, etc.
• Parasitic – Toxoplasma gondii is the most common parasitic infection affecting CNS in HIV/AIDS patients with a CD4 < 100. It carries a predilection for the basal ganglia and appears as, often multiple, ring-enhancing lesions on MRI/CT imaging. Patient often present with seizure. While very difficult to differentiate from CNS lymphoma with imaging alone, CSF and serum serologic testing (IgG) can be used to help guide the diagnosis.
• Neoplastic – Primary CNS lymphoma is the most common neoplastic affecting the CNS in HIV/AIDS patients. Consider it as an opportunistic B-cell disease. It most often occurs in patients with a CD4 < 50. CT and MRI imaging is typically a single, ring-enhancing, space-occupying lesion. The frontal lobe is typically affected and thus patients often present with AMS and personality changes. Toxoplasma and primary CNS lymphoma are difficult to distinguish on imaging alone, thus lymphoma is associated with increased CSF protein, +EBV PCR in the CSF, and ultimately confirmed with CSF cytology.

References:

1. Gage, J et al. "Brain Lesion and AIDS." BUMC Proceedings. 2000 Oct; 13(4): 424-9.
2. <https://commons.wikimedia.org/wiki/File:Tumor_PrimaryCNSLymphoma_T2.JPG>

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Authored by: GREGORY WIGGER, MD