Answer of January 2007

Clinical History:

A 61-years-old man whom is HIV positive has a history of psoriasis and CMV gastritis.  MRI brain (Axial T1FLAIR, Axial T2W, Axial T1+Contrast, Sagittal T1+Contrast, Diffusion weighted, Perfusion weighted) was performed

Diagnosis:

Toxoplasmosis

Discussion:

MR brain showed a mass measured at 2.0cm located at the left lentiform nucleus. It is hypointense to normal brain parenchyma on both T1-weighted and T2-weighted images, and shows ring nhancement after contrast enhancement. Its margin is irregular with uneven thickness. Surrounding oedmea with mild local mass effect is seen. The central bulk of the lesion demonstrates increased diffusion on diffusion-weighted and hypoperfusion on perfusion-weighted study. Multiple tiny enhancing nodules are also seen superior to the mass on the sagittal scan, suggestive of satellite lesions. The overall findings are compatible with cerebral toxoplasmosis.