“Bubbly-Appearing” Intraventricular Mass



“Bubbly-Appearing” Intraventricular Mass


Bronwyn E. Hamilton, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Choroid Plexus Cysts


Less Common



  • Neurocysticercosis


  • Central Neurocytoma


  • Ependymoma


  • Subependymoma


  • Epidermoid Cyst


  • Cavernous Malformation


  • Ependymal Cyst


Rare but Important



  • Choroid Plexus Papilloma


  • Choroid Plexus Carcinoma


  • Parasites, Miscellaneous


  • Astroblastoma


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Purely cystic intraventricular masses are usually benign



    • Xanthogranulomas > > ependymal or inflammatory cysts


  • Only truly common “bubbly-appearing” intraventricular masses = choroid plexus cysts (xanthogranulomas)


Helpful Clues for Common Diagnoses



  • Choroid Plexus Cysts



    • Benign xanthogranulomas


    • Choroid plexus glomi, bilateral


    • Increased prevalence with age


    • Usually asymptomatic (rarely cause obstruction)


    • Histologically most are xanthogranulomas



      • Benign degenerative process


      • Typically FLAIR hyperintense


      • May restrict on DWI


      • Inhomogeneous enhancement common


Helpful Clues for Less Common Diagnoses



  • Neurocysticercosis



    • Often show rim enhancement


    • Look for characteristic scolex, parenchymal/cisternal lesions


    • Small intraventricular cysts best seen on FLAIR


  • Central Neurocytoma



    • Who grade II neoplasm


    • Younger age patients



      • Nearly 1/2 occur in the 3rd decade


      • 75% between 2nd-4th decades


    • Location



      • Arises from septum pellucidum or lateral ventricle wall


      • Anterior (near foramen of Monro), mid-body > > atrium, temporal horn


      • Less common: 3rd ventricle


      • Rare: Extraventricular central neurocytoma


      • 13% bilateral


    • Imaging



      • Cyst-like areas seen in 2/3 of cases


      • Moderate enhancement is typical


      • Punctate calcifications in up to 1/2


      • Hemorrhage not uncommon


  • Ependymoma



    • WHO grade II neoplasms


    • Arises from differentiated ependymal cells lining ventricles, central canal of the spinal cord


    • Mean age ˜ 6 years


    • Location



      • 58% 4th ventricle


      • 42% lateral, 3rd ventricles


      • Less common: Extraventricular ependymoma


    • Imaging



      • Ca++ in 40-80%


      • Occasional intratumoral hemorrhage yields blood-fluid levels


      • Contrast-enhancement varies; usually intense but spares the cyst-like regions


      • Extension beyond ventricular margins (paraventricular) not uncommon


  • Subependymoma



    • Middle-aged, older adults


    • Most located within the 4th, frontal horn of lateral ventricles


    • Varied enhancement: None to intense, calcification, cyst formation may occur


    • Extension of a subependymoma beyond the ventricular margins is rare, unlike for ependymoma


  • Epidermoid Cyst



    • DWI most specific: Restricted diffusion


    • FLAIR next most helpful sequence, showing “gray” CSF or incomplete CSF suppression


  • Cavernous Malformation



    • Intraventricular location is uncommon



    • Imaging appearance like cavernous malformations elsewhere


    • GRE or SWI sequence helpful to assess for susceptibility due to blood products


  • Ependymal Cyst



    • Lacks enhancement


    • CSF signal all sequences (FLAIR most specific)


Helpful Clues for Rare Diagnoses



  • Choroid Plexus Papilloma



    • Nearly half present in 1st decade


    • WHO grade I (carcinoma is WHO grade III)


    • Presentation with hydrocephalus common; can be due to mechanical obstruction and/or overproduction of CSF


    • Locations: Lateral ventricle most common site (50% of cases) > 4th ventricle (40%; most common in adults) > 3rd ventricle (5%)


    • Imaging



      • Cauliflower-like lobulated tumor, usually with moderate or intense enhancement


      • Hemorrhage, cyst formation may occur


      • Necrosis and/or parenchymal invasion suggest choroid plexus carcinoma


      • Flow voids common


      • Pure “cystic” variant may occur within ventricles, subarachnoid spaces


  • Astroblastoma



    • “Bubbly” appearance common


    • Parenchymal > > intraventricular


Other Essential Information



  • Enhancing intraventricular tumors may require MR neuraxis screening for drop metastasis, particularly when choroid plexus tumors and ependymoma are suspected


  • Nonenhancing cystic lesions with DWI restriction characteristic for epidermoid cysts


  • Neurocysticercosis can rarely mimic other intraventricular cysts, such as colloid cyst



    • Cryptococcal infection can present in a similar fashion to cysticercosis



SELECTED REFERENCES

1. Bell JW et al: Neuroradiologic characteristics of astroblastoma. Neuroradiology. 49(3):203-9, 2007

2. Mathews M et al: Intraventricular cryptococcal cysts masquerading as racemose neurocysticercosis. Surg Neurol. 67(6):647-9, 2007

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on “Bubbly-Appearing” Intraventricular Mass

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