A 74-year-old, right-handed man with a medical history of hypertension, hyperlipidemia, and type 2 diabetes mellitus was found lying on the ground by his family and was brought to the emergency department, where he was found to have left facial drooping and weakness. On admission, a T1 post-contrast axial MRI and apparent diffusion coefficient diffusion-weighted imaging were performed.
C. Primary central nervous system (CNS) lymphoma
Eventual biopsy confirmed the imaging suspicion for primary CNS lymphoma. The T1 post-contrast MRI shows a multifocal intracranial mass with homogenous enhancement, and the apparent diffusion coefficient diffusion-weighted image shows restricted diffusion. Although WHO grade 1 meningioma typically has homogenous enhancement, they are also typically well circumscribed, dural-based, and do not show restricted diffusion. High-grade glioma more typically shows areas of necrosis, and contrast enhancement is typically irregular and peripheral to necrotic areas. Areas of necrosis in high-grade glioma typically have facilitated diffusion. Neurotoxoplasmosis classically shows ring enhancement on post-contrast imaging.
1. Haldorsen IS, Kråkenes J, Krossnes BK, et al. CT and MR imaging features of primary central nervous system lymphoma in Norway, 1989-2003. AJNR Am J Neuroradiol. 2009;30:744-51.