Primary central nervous system lymphoma MRI

Overview
Primary CNS lymphoma is a primary intracranial tumor usually present in those with severe immunosuppression --- commonly in those with AIDS --- and represents around 20% of all cases of lymphomas in HIV infection (other types being Burkitt's lymphoma and immunoblastic lymphoma).

MRI
MRI or contrast enhanced CT usually shows multiple (1 to 3) 3- to 5-cm ring-enhancing lesions in almost any location, but usually deep in the white matter. The major differential diagnosis is cerebral toxoplasmosis, which is also prevalent in AIDS patients and also presents with a ring-enhanced lesion, although the contrast enhancement is more pronounced in toxoplasmosis and it presents with more lesions.