MRCP Part 2 question #2

A 47-year-old man with HIV disease presents to hospital with a tonic-clonic seizure. He had initially presented six months previously with Pneumocystis carinii pneumonia with a CD4 T-lymphocyte count of 10 cells/mm3 and had subsequently started on highly active antiretroviral therapy. His most recent CD4 count, taken one month prior to his new presentation, was 50 cells/mm3. On examination he has no focal weakness, but both plantar responses are extensor. Fundoscopy is normal.

A CT scan of his brain is shown.


What is the diagnosis?


(Please select 1 option)


0. AIDS-related dementia
0. Brain abscess
0. Cerebral toxoplasmosis
0. Primary CNS lymphoma
0. Progressive multifocal leukoencephalopathy

Answer: Cerebral toxoplasmosis

Toxoplasma encephalitis is the commonest cause of focal brain disease in HIV/AIDS, occurring at CD4 counts of less than 100 cells/mm3. Alhough Toxoplasma gondii may also cause a retinitis in association with HIV/AIDS, it need not occur concomitantly with CNS disease. The typical appearance on CT is of multiple ring-enhancing lesions, as shown here. Treatment is with pyrimethamine + sulfadiazine. Patients must subsequently be maintained on long-term suppressive therapy to prevent relapse.