A 38-year-old woman with HIV (CD4 650, VL 500 for 3 years. What is the most appropriate initial approach?

Start whole-brain radiotherapy for likely lymphoma

Start empirical Pyrimethamine/Sulfadiazine and reassess at 2 weeks

Start anti-TB therapy for tuberculoma

Start IV Aciclovir for HSV encephalitis

Ring-Enhancing Lesion High CD4 — SCE Infectious Diseases MCQ

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HardHIV MedicineRing-Enhancing Lesion High CD4SCE Infectious Diseases

A 38-year-old woman with HIV (CD4 650, VL <50 on DTG/TAF/FTC) develops new-onset seizures. MRI shows a single ring-enhancing lesion in the right parietal lobe. Toxoplasma IgG is positive. CD4 has been consistently >500 for 3 years. What is the most appropriate initial approach?

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Correct answer: D — Stereotactic biopsy rather than empirical anti-Toxoplasma therapy — at CD4 >500, Toxoplasma encephalitis is very unlikely

Although Toxoplasma IgG positivity indicates prior exposure, Toxoplasma encephalitis almost exclusively occurs at CD4 <200, and is very rare above CD4 500. In a well-controlled HIV patient with high CD4, the differential for a ring-enhancing lesion shifts toward primary CNS lymphoma, metastasis, glioma, or brain abscess. Empirical anti-Toxoplasma therapy is not appropriate at this CD4 level — stereotactic biopsy for definitive tissue diagnosis is the correct approach.

Reference: BHIVA 2022 – OI guidelines; NICE NG99 2018 – Brain tumours