From the Guidelines
Central nervous system (CNS) lymphoma is characterized by distinct neuroimaging findings, including homogeneous enhancement on MRI, typically with restricted diffusion, and variable intensity on T2-weighted images, as well as marked and uniform contrast enhancement following gadolinium administration 1. The diagnosis of CNS lymphomas relies heavily on magnetic resonance imaging (MRI) of the brain and spinal cord, which is essential for identifying supportive evidence and excluding differential diagnoses, such as infectious diseases 1. Key MRI findings in CNS lymphoma include:
- Homogeneous enhancement on T1-weighted images after gadolinium administration
- Variable intensity on T2-weighted images
- Restricted diffusion due to hypercellularity
- Periventricular location, often contacting the ventricular or meningeal surfaces
- Solitary or multiple lesions
- Less surrounding edema than expected for their size compared to other brain tumors Two categories of CNS involvement in CNS lymphoma can be distinguished by MRI imaging: the diffuse form and the tumoral form 1. The diffuse form is characterized by:
- Lymphoid cell infiltration in the leptomeningeal sheaths and perivascular spaces
- Contrast enhancement and/or thickening of meningeal sheaths on T1-weighted images after gadolinium administration The tumoral form is characterized by:
- Unifocal or multifocal lesions, usually located in the deep subcortical hemispheric regions
- Well-demonstrated on T1-weighted images, FLAIR sequences, and T1-weighted images after gadolinium administration Other characteristic findings of leptomeningeal lymphoma include abnormal contrast enhancement of cranial and spinal nerves, as well as thickening and enhancement of the cauda equina 1.
From the Research
Neuroimaging Findings in CNS Lymphoma
- Neuroimaging plays a crucial role in the diagnosis and evaluation of Central Nervous System (CNS) lymphoma, with contrast enhancement on imaging being highly sensitive at the time of diagnosis 2.
- The sensitivity of contrast enhancement is 98.9% in immunocompetent lymphoma and 96.1% in human immunodeficiency virus-related CNS lymphoma 2.
- Brain and body imaging are essential components of the diagnostic workup for suspected CNS lymphoma, helping to identify lesions and determine the extent of disease involvement 2, 3.
Characteristics of CNS Lymphoma on Neuroimaging
- CNS lymphoma can present with various neuroimaging characteristics, including focal lesions, diffuse infiltration, and leptomeningeal enhancement 4, 5.
- The location and appearance of lesions on neuroimaging can vary depending on the subtype of CNS lymphoma and the involved CNS compartments 5, 3.
- Neuroimaging findings can be nonspecific, and a high level of suspicion is required to diagnose CNS lymphoma, particularly in immunocompetent patients 6, 3.
Diagnostic Approach
- A systematic approach to diagnosis, including neuroimaging, cerebrospinal fluid (CSF) analysis, and tissue biopsy, is necessary to confirm the diagnosis of CNS lymphoma 2.
- CSF cytology, flow cytometry, and molecular testing can help establish the diagnosis, although their sensitivity and specificity may vary 2, 3.
- A combined stepwise approach, incorporating multiple diagnostic modalities, can facilitate an expeditious and comprehensive evaluation for suspected CNS lymphoma 2.