Ring-Enhancing Lesions

Ring-Enhancing Lesions
Bernadette L. Koch, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Abscess
  • Pilocytic Astrocytoma
  • Neurocysticercosis
Less Common
  • Demyelinating Disease
    • ADEM
    • Multiple Sclerosis
  • Ganglioglioma
Rare but Important
  • Aneurysm (Thrombosed)
  • Other Infections
    • Tuberculosis
    • Fungal Diseases
    • Acquired Toxoplasmosis
    • Lyme Disease
  • Other Neoplasms
    • Parenchymal Metastases
    • Lymphoma, Primary CNS
    • Glioblastoma Multiforme
  • Subacute Cerebral Infarction
  • Subacute Intracerebral Hematoma
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
  • Solitary ring-enhancing lesions most often tumor, infection, or demyelination
  • Metastatic lesions typically subcortical; primary tumors more often deep
  • Smooth, thin rim of enhancement typical of organizing abscess
  • Thick, irregular rim of enhancement suggests necrotic neoplasm
Helpful Clues for Common Diagnoses
  • Abscess
    • Pyogenic, fungal, granulomatous, or parasitic
    • Single or multiple
    • Thin, smooth rim contrast enhancement (CE)
    • Thin T2 hypointense rim
    • Restricted diffusion central cavity
    • MRS: ↑ amino acids (0.9 ppm), succinate (2.4 ppm), and acetate (1.92 ppm)
    • Early capsule stage: Moderate vasogenic edema and mass effect
    • Late capsule stage: Edema & mass effect ↓
    • ± ventriculitis &/or meningitis
    • ± sinusitis or mastoiditis as a cause
  • Pilocytic Astrocytoma
    • Cerebellum > optic nerve/chiasm > adjacent to 3rd ventricle > brainstem
    • Peak: 5-15 years of age
    • Variable appearance
      • Nonenhancing cyst + CE mural nodule
      • CE cyst wall + CE mural nodule
      • Solid with necrotic center + heterogeneous CE
      • Solid + homogeneous CE
    • Cyst may accumulate contrast on delayed imaging
    • “Aggressive” metabolite spectrum on MRS: ↑ choline, ↓ NAA; however, clinical behavior frequently benign
  • Neurocysticercosis
    • Pork tapeworm, Taenia solium
    • 5-20 mm cyst
    • ± 1-4 mm eccentric scolex
    • Single or multiple
    • Cisterns > parenchyma > intraventricular
    • Appearance depends on developmental stage and host response
      • Simple cyst ± enhancement → complicated cyst + thick enhancing wall
    • ± surrounding edema
    • ± calcification in healed stage
Helpful Clues for Less Common Diagnoses
  • Demyelinating Disease
    • ADEM
      • Autoimmune-mediated demyelination: Brain and spinal cord
      • Typically monophasic, 10-14 days after viral infection or vaccination
      • “Multiphasic” or “relapsing” ADEM may be same entity as MS
      • Multifocal hyperintense T2 and FLAIR signal WM and BG > GM; cerebrum > cerebellum and brainstem
      • Bilateral common, but asymmetric
      • Punctate or ring-like enhancement (complete or incomplete)
      • MRS: ↓ NAA, ± ↑ lactate and choline in acute lesions
    • Multiple Sclerosis
      • Probably autoimmune-mediated demyelination in genetically susceptible individuals
      • Relapsing-remitting course
      • Imaging may be identical to ADEM
      • Multifocal lesions PVWM, subcortical U-fibers, brachium pontis, brainstem, and spinal cord
      • Infratentorial: Children > adults
      • Perivenular extension along path of deep medullary veins = “Dawson fingers”
      • T1WI: Hypointense lesions = axonal destruction (“black holes”)
      • T2 and FLAIR: Hyperintense linear foci radiating from ventricles
      • Nodular or ring enhancement, occasionally semilunar CE or large tumefactive enhancing rings
      • MRS: ↓ NAA, ↑ choline, ↑ myoinositol
  • Ganglioglioma
    • Temporal > parietal > frontal > occipital > BG/thalamus, hypothalamus/optic pathway, cerebellum
    • Solid, cystic, or mixed; usually cortical-based lesion, without surrounding edema
    • Ca++ common
    • Larger and more cystic lesions in children
    • Variable degree of CE: Diffuse or ring-like
    • Marked meningeal enhancement in desmoplastic infantile ganglioglioma
    • Rarely poorly defined, infiltrating lesion
Helpful Clues for Rare Diagnoses
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Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Ring-Enhancing Lesions

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