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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