Abstract Introduction In patients with advanced AIDS, cerebral toxoplasmosis and primary central nervous system (CNS) lymphoma are the most common causes of ring-enhancing brain lesions. These two conditions may present with overlapping clinical and radiographic features, complicating diagnosis. Differentiating between them is essential, as management strategies and prognoses differ substantially. Case Presentation A 29-year-old man with newly diagnosed AIDS (CD4 80 cells/μL, viral load 247,000 copies/mL) presented with progressive visual changes and headache. MRI of the brain demonstrated multiple ring-enhancing lesions involving bilateral basal ganglia and thalami, concerning for CNS toxoplasmosis versus primary CNS lymphoma. Aqueous fluid PCR and serum IgG were positive for Toxoplasma gondii. The patient was started on sulfamethoxazole/trimethoprim but developed a hypersensitivity reaction, prompting transition to pyrimethamine and leucovorin. Antiretroviral therapy was initiated, and corticosteroids were added for immune reconstitution inflammatory syndrome (IRIS) prophylaxis.Despite two weeks of therapy, follow-up MRI revealed lesion progression and increased edema, raising suspicion for CNS lymphoma. To facilitate brain biopsy, corticosteroids were discontinued. Within 48 hours, the patient became unresponsive with decerebrate posturing and rightward gaze deviation. CT head demonstrated worsening cerebral edema. The patient was intubated and treated with mannitol and hypertonic saline. Corticosteroids were reinitiated, but his neurologic status continued to decline, progressing to GCS 3 with fixed, dilated pupils. Brain death was confirmed two days later. Discussion This case highlights the diagnostic and management challenges of ring-enhancing brain lesions in AIDS. Corticosteroids are frequently used to manage cerebral edema but can obscure lymphoma diagnosis by diminishing lesion size and cytologic yield. Conversely, abrupt withdrawal may precipitate rapid neurologic decline in patients with ongoing intracranial pathology. In this case, steroid discontinuation likely unmasked uncontrolled cerebral edema, leading to herniation and brain death despite aggressive medical therapy.Clinicians should maintain close neurologic monitoring when withholding corticosteroids in patients with suspected CNS lymphoma. If deterioration occurs, empiric steroid reinitiation should be promptly considered. Early multidisciplinary collaboration between neurology, infectious disease, oncology, and critical care teams is vital to balance diagnostic clarity with neurologic stability in immunocompromised patients. This abstract is funded by: None
Liu et al. (Fri,) studied this question.