Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Primary CNS Lymphoma


KEY FACTS

Terminology

  • Malignant primary CNS neoplasm primarily composed of B lymphocytes (PCNSL)

Imaging

  • Best diagnostic clue: Enhancing lesion(s) within basal ganglia &/or periventricular white matter

  • 60-80% supratentorial

    • Often involve, cross corpus callosum

    • Frequently contact, extend along ependymal surfaces

  • Classically hyperdense on CT (helpful for diagnosis)

  • Diffusely enhancing periventricular mass in immunocompetent patients

  • May see hemorrhage or necrosis in immunocompromised patients

  • DWI: Low ADC values

  • PWI: Low relative cerebral blood volume ratios

  • Periventricular location and subependymal involvement is characteristic of PCNSL

  • Corpus callosum involvement may be seen with PCNSL, glioblastoma (GBM), and rarely metastases or demyelination

Top Differential Diagnoses

  • Acquired toxoplasmosis

  • GBM

  • Abscess

  • Progressive multifocal leukoencephalopathy

Pathology

  • 98% diffuse large B-cell, non-Hodgkin lymphoma

Clinical Issues

  • Imaging and prognosis vary with immune status

  • 6.6% of primary brain tumors, incidence rising

  • Poor prognosis

  • Stereotactic biopsy, followed by chemotherapy, ± XRT

Axial graphic shows multiple periventricular lesions with involvement of the basal ganglia, thalamus, and corpus callosum, typical of primary CNS lymphoma (PCNSL). Note the extensive subependymal spread of the disease
. PCNSL typically extends along ependymal surfaces.

Axial T1 C+ MR in a 63 year old shows the classic appearance of PCNSL. Note the multiple homogeneously enhancing masses in the basal ganglia along the ependymal lining of the ventricular system
.

Axial T1 C+ MR shows a homogeneously enhancing mass crossing the corpus callosum splenium
typical of PCNSL in this 76-year-old man with a headache. The main differential consideration would be a glioblastoma, which typically has a more heterogeneous appearance.

Axial T1WI C+ MR in an AIDS patient shows a ring-enhancing mass with a target sign
, suggestive of toxoplasmosis. Hemorrhage, necrosis, and ring-enhancing lesions are typical of PCNSL in AIDS patients.

TERMINOLOGY

Abbreviations

  • Primary central nervous system lymphoma (PCNSL)

Definitions

  • Extranodal malignant lymphoma arising in CNS in absence of systemic lymphoma

  • Malignant primary CNS neoplasm primarily composed of B lymphocytes

IMAGING

General Features

  • Best diagnostic clue

    • Enhancing lesion(s) within basal ganglia, periventricular white matter (WM)

  • Location

    • 60-80% supratentorial

      • –

        Frontal, temporal, and parietal lobes most common

    • Deep gray nuclei commonly affected (10%)

    • Lesions cluster around ventricles, gray-white matter junction

    • Often involve, cross corpus callosum (5-10%)

    • Frequently abut, extend along ependymal surfaces

    • Posterior fossa, sella, pineal region uncommon

    • Spine involvement rare (1%)

    • May involve leptomeninges or dura (more common in secondary lymphoma)

      • –

        Secondary leptomeningeal spread in 30-40% of PCNSL

      • –

        Primary leptomeningeal lymphoma (5-8%)

  • Morphology

    • Solitary mass or multiple lesions

    • May be circumscribed or infiltrative

CT Findings

  • NECT

    • Classically hyperdense; may be isodense

    • ± hemorrhage, necrosis (immunocompromised)

  • CECT

    • Common: Moderate, uniform (immunocompetent)

    • Less common: Ring (immunocompromised)

    • Rare: Nonenhancing (infiltrative)

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts