| Glioblastoma |
> 65 years old, primary brain tumor |
Irregular, thick-walled enhancement; central necrosis; significant vasogenic edema |
Single lesion (usually); cerebral hemispheres; crosses corpus callosum ("butterfly") |
Crosses midline; irregular "serpentine" enhancement; arises de novo in brain parenchyma |
| Toxoplasmosis |
HIV/AIDS (CD4 < 100); immunocompromised |
Ring-enhancing lesions; target-like appearance |
Multiple (< 2 cm); Basal ganglia & gray-white junction |
Multiple lesions in the basal ganglia in an AIDS patient; improves with empiric therapy |
| Primary CNS Lymphoma |
HIV/AIDS (CD4 < 50); immunocompromised; EBV association |
Homogeneous, intense enhancement; periventricular |
Single (usually); Periventricular; may touch ependymal surface |
Single, periventricular, solid enhancement (less often ring-enhancing); EBV+ in CSF |
| Metastasis |
Known primary cancer (lung, breast, melanoma, renal) |
Well-circumscribed lesions with significant edema |
Multiple (usually); Gray-white matter junction |
History of primary cancer; lesions are typically spherical and located at the gray-white junction |
| Pyogenic Abscess |
Bacteremia, sinusitis, otitis, dental infection |
Smooth, thin-walled ring enhancement; central restricted diffusion (DWI) |
Can be single or multiple |
Bright signal on DWI is highly specific for abscess; often has a smooth, thin capsule |
| Neurocysticercosis |
History of travel/living in endemic area (e.g., Latin America) |
Cysts in various stages: non-enhancing → ring-enhancing → calcified lesions ("brain stones") |
Multiple, in different stages |
History of exposure + presence of calcified lesions and/or scolex ("dot-in-a-box") |
| Aspergillus |
Severely immunocompromised (neutropenia, transplant) |
Angioinvasion leading to hemorrhage/infarct; T2-hypointense rim |
Often multiple |
Angioinvasive nature (hemorrhage/infarct); associated with severe immunosuppression |
| Nocardiosis |
Immunocompromised (chronic steroids, transplant); pulmonary nocardiosis |
Ring-enhancing lesions, may be multiloculated or "bilobed" |
Multiple |
Concomitant pulmonary infection; diagnosis via culture (gram-positive, branching filaments) |
| Multiple Sclerosis |
Young female (20-40 years); relapsing-remitting neuro deficits |
"Tumefactive" MS can mimic tumor; incomplete "open-ring" enhancement |
Multiple, disseminated in time & space |
"Open-ring" enhancement (points away from ventricle); other classic MS lesions (Dawson's fingers) |