Typical imaging features of primary and secondary CNS lymphoma
| Primary CNS lymphoma | Secondary CNS Lymphoma | |
|---|---|---|
| Primary site of CNS involvement | Brain parenchyma, ∼100% | Brain parenchyma, ∼1/3; leptomeninges, ∼2/3 |
| Parenchymal CNS lymphoma | Leptomeningeal CNS lymphoma | |
| Typical location | Periventricular and superficial brain regions | Leptomeninges |
| CT findings | Iso- or hypodense lesions with marked CE | Leptomeningeal, subependymal, dural, or cranial nerve CE; superficial cerebral lesion; communicating hydrocephalus |
| MRI findings | T1: hypo- or isointense lesions, moderate-marked CE | Leptomeningeal, subependymal, dural, or cranial nerve CE; superficial cerebral lesion; communicating hydrocephalus |
| T2: iso- or hyperintense lesions; often hypointense to gray matter | ||
| Enhancement pattern | Non-AIDS patients: homogeneous CE, ∼90%; ring-CE, ∼0%-13% | Leptomeningeal, subependymal, dural, or cranial nerve CE |
| AIDS patients: irregular CE common; ring-CE, ∼75% |