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Primary Central Nervous System Lymphoma (PCNSL)

Last Updated: March 27, 2020

Open Table of Contents: Primary Central Nervous System Lymphoma (PCNSL)

Figure 1: The patchy and solid enhancement of lymphoma on postcontrast T1WI (top row left, top row right) and abutment of an ependymal surface is typical in immunocompetent patients. This lymphoma crosses the midline through the anterior body of the corpus callosum. Low T2 (bottom row right) and ADC (bottom row left) signal indicate hypercellularity. This lymphoma is also inciting a moderate amount of T2-hyperintense surrounding vasogenic edema.

Figure 2: This AIDS patient's inferior left frontal primary CNS lymphoma demonstrates a large amount of edema but is difficult to delineate on noncontrast CT (left). After administration of contrast (right), the centrally necrotic lesion is more apparent.

Figure 3: Corresponding MRI brain for patient in Figure 2. Axial T1 post-contrast (top row left), T2FS (top row right), DWI (bottom row left), and ADC (bottom row right) images demonstrate a T2 hypointense, ring-enhancing mass with a rim of restricted diffusion. Note that centrally the mass does not demonstrate restricted diffusion. The enhancement pattern and diffusion characteristics are compatible with this immunocompromised patient’s biopsy proven B-Cell lymphoma. An additional consideration for this immunocompromised patient prior to biopsy included toxoplasmosis which can look identical to this case.

Basic Description

  • Extranodal malignant lymphoma arising in the central nervous system (CNS) without concurrent systemic lymphoma
  • Primarily non-Hodgkin/diffuse large B-cell lymphoma


  • Associated with Epstein-Barr virus infection in immunocompromised patients
    • PCNSL is an AIDS-defining illness
  • Malignant cells infiltrate perivascular spaces and blood vessels

Clinical Features

  • Immune competent: mean patient age 60 years
  • Immunocompromised (HIV/AIDS, post-transplant, inherited immunodeficiency such as Wiskott-Aldrich syndrome): younger ages
  • Male gender predilection
  • Common presenting signs/symptoms: AMS, focal neurologic deficits, cognitive decline, headache
  • Treatment: biopsy, chemotherapy ± radiation; steroids may offer some short-term benefit
  • Poor prognosis
    • Immune competent patients: median survival < 5 years
    • Immunocompromised status, multiple lesions, and older age are negative prognosticators

Imaging Features

  • General
    • Imaging appearance varies with immune status
      • Hypercellular mass
      • Well-marginated or infiltrating
      • Solitary or multiple
      • Nearly always enhances, with homogeneous, patchy, and/or peripheral pattern
    • Usually supratentorial and involving the periventricular white or deep gray matter
    • Commonly spreads across corpus callosum or involves the ventricles

      • Often abuts ependymal surface with subependymal spread
  • CT

    • Hyperdense mass
    • ± Necrosis, hemorrhage
    • Homogeneous/patchy enhancement on contrast-enhanced CT; may be ring-enhancing if immunocompromised
  • MRI

    • T1WI: homogeneously iso- to hypointense; may appear heterogeneous due to necrosis or hemorrhage in the immunocompromised
    • T2WI: homogeneously iso- to hypointense; may appear heterogeneous due to necrosis or hemorrhage in the immunocompromised
    • FLAIR: homogeneously iso- to hypointense
    • DWI: diffusion restriction is often seen, although an unreliable differentiator of GBM
    • MR spectroscopy/MR perfusion: elevated Cho, decreased NAA; less relative cerebral blood volume (rCBV) elevation than GBM

Imaging Recommendations

  • MRI without and with IV contrast including DWI and MR perfusion

For more information, please see the corresponding chapter in Radiopaedia.

Contributor: Rachel Seltman, MD; Jacob A. Eitel, MD

DOI: https://doi.org/10.18791/nsatlas.v1.03.01.36


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