A 32-year-old woman with poorly controlled HIV infection presents with headache and right-sided weakness. MRI shows multiple ring-enhancing lesions at gray-white matter junctions with significant surrounding edema. CSF PCR is positive for Toxoplasma gondii. The tissue response in these lesions is characterized predominantly by which pattern?
- A Caseating granulomas with Langhans giant cells
- B Necrotizing abscess with free tachyzoites and encysted bradyzoites at the rim ✓
- C Multinucleated giant cells with microglial nodules containing viral inclusions
- D Demyelination with lipid-laden macrophages and bizarre reactive astrocytes
Explanation
Cerebral toxoplasmosis in AIDS produces multifocal necrotizing abscesses, typically at the gray-white junction. Active lesions show central coagulative necrosis surrounded by inflammation containing free tachyzoites and pseudocysts packed with bradyzoites at the lesion margin. Caseating granulomas indicate tuberculosis. Multinucleated giant cell encephalitis is characteristic of HIV itself. Demyelination with macrophages and bizarre astrocytes describes progressive multifocal leukoencephalopathy caused by JC virus, a key differential for white matter lesions in AIDS.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.