Primary CNS Lymphoma (PCNSL)

Axial T2W and postcontrast T1W MR images show two enhancing intra-axial masses (arrowheads) in the right cerebral hemisphere, involving the deep white matter. The frontal lobe mass crosses the midline at the corpus callosum (arrow), and is in contact with the ependyma.

Facts: PCNSL

• Rare, 1% of all primary brain tumors
• Incidence is rising in both HIV and non-HIV groups
• Uncertain origin because the CNS does not have endogenous lymphoid tissue or lymphatic circulation
• Three populations at risk: organ transplant recipients, patients with congenital immunodeficiency syndromes and AIDS/other immunodeficiency

Imaging

• Masses in deep gray matter structures, periventricular region and corpus callosum
• Up to 75% of masses are in contact with ependyma
• Enhancing homogeneously
• Some surrounding edema but less pronounced than gliomas or metastasis
• Do not calcify, rarely hemorrhage
• Imaging differential diagnosis: glioblastoma, metastasis, sarcoidosis

Our case: primary CNS lymphoma, non-Hodgkin type, in a non AIDS patient.

Reference:

Atlas SW. Magnetic Resonance Imaging of the Brain and Spine, Volume 1, 4th edition, 2008.