Multiple Hypointense Foci on T2

Multiple Hypointense Foci on T2

Nancy J. Fischbein, MD



  • Neoplasm

    • Lymphoma

    • Metastases, Parenchymal

    • Multifocal Glioma

  • Atypical Infection

    • Bacterial (TB, Nocardia)

    • Fungal Diseases

    • Toxoplasmosis, Acquired

Less Common

  • Neurosarcoid

  • Neoplasm-like Conditions

    • Post-Transplant Lymphoproliferative Disorder (PTLD)

    • Lymphomatoid Granulomatosis


Key Differential Diagnosis Issues

  • These lesions show mild T2 hypointensity or “intermediate” signal intensity (SI)

    • Lesions are often isodense or mildly hyperdense to gray matter (GM) on CT

  • Lesions in this ddx often associated with vasogenic edema & “bright” on T2/FLAIR, but are centrally iso- or hypointense to GM

  • Neoplasms included are generally small round blue-cell tumors (e.g., lymphoma) or highly cellular metastases with high nuclear-to-cytoplasmic ratio

  • DWI variable; may be mildly reduced due to ↑ cellularity of some of these lesions

Helpful Clues for Common Diagnoses

  • Lymphoma

    • Both primary & secondary CNS lymphoma may present as intermediate SI masses

      • PCNSL often limited to brain parenchyma

      • SCNSL more likely to involve leptomeninges, dura, bone

  • Metastases, Parenchymal

    • Highly cellular, non-necrotic metastases

    • Breast & lung mets often T2 intermediate

  • Atypical Infection

    • Pyogenic abscesses typically have central ↑ SI on T2WI because of pus

    • Atypical non-pyogenic “abscesses” often have intermediate SI on T2WI

      • In TB, due to caseous material

      • Fungal: Due to absence of pus, concentration of paramagnetic ions

      • Toxo: May show “eccentric target sign”

    • Variable reduced diffusion

Helpful Clues for Less Common Diagnoses

  • Neurosarcoid

    • Parenchymal nodules & masses often intermediate T2 SI due to high cellularity

    • Look for dural/leptomeningeal disease

  • Post-Transplant Lymphoproliferative Disorder (PTLD)

    • Parenchymal lesions resemble lymphoma

  • Lymphomatoid Granulomatosis

    • Rare lymphoproliferative disorder

    • Typical: Punctate & linear enhancement

    • Large coalescent nodules T2 intermediate

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Multiple Hypointense Foci on T2

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