Wednesday, December 10, 2008


A 40 year old AIDS patient with CD4 count of 95 presents with a headache, confusion, and fever. A T1-weighted MRI with gadolinium is shown above.

Challenge: What's the diagnosis?

Image shown under fair use.


Alex said...


Stephanie said...

toxoplasma gondii

Craig Chen said...

Steph > Alex :P.
Crypto is an opportunistic CNS infection but it causes a meningoencephalitis. According to UpToDate, "Mass lesions in the CNS due to C. neoformans are so rarely seen in patients with HIV infection that coincident diagnoses such as toxoplasmosis, lymphoma, tuberculosis and syphilis should be considered."

This is toxoplasma encephalitis which occurs in AIDS patients with CD4 count < 100. The causative organism is the intracellular protozoan parasite Toxoplasma gondii. The image shows multiple ring enhancing lesions with mass effect, suggesting toxoplasmosis (other things on the differential include primary CNS lymphoma, TB, neurocystercerosis).

Source: UpToDate.

Alex said...

oh nuts.. knew it was "ring enhancing lesions" but mixed up the bug