Fourth Ventricle Mass



Fourth Ventricle Mass


Karen L. Salzman, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Medulloblastoma (PNET-MB)


  • Ependymoma


  • Pilocytic Astrocytoma


  • Brainstem Glioma, Pediatric


Less Common



  • Subependymoma


  • Choroid Plexus Papilloma


  • Neurocysticercosis


  • Epidermoid Cyst


  • Hemangioblastoma


  • Metastasis, Intraventricular


  • Atypical Teratoid-Rhabdoid Tumor (ATRT)


Rare but Important



  • “Trapped” 4th Ventricle


  • Ependymal Cyst


  • Dermoid Cyst


  • Lipoma


  • Encephalocraniocutaneous Lipomatosis


  • Rosette-Forming Glioneuronal Tumor


  • Central Neurocytoma


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Age of patient is very helpful in differentiating lesions of the 4th ventricle


  • For many pediatric 4th ventricle masses, imaging of entire neuraxis prior to surgery is recommended (medulloblastoma, choroid plexus tumors, ATRT)


  • MR with contrast is best imaging modality


  • Sagittal images helpful to determine tumor origin (location in 4th ventricle)


Helpful Clues for Common Diagnoses



  • Medulloblastoma (PNET-MB)



    • Arises from vermis or roof of 4th ventricle (superior medullary velum)


    • Small round blue cells: Hyperdense on CT


    • 50% have CSF dissemination at diagnosis


    • Solid, enhancing mass within 4th ventricle


    • Hydrocephalus in > 90%


  • Ependymoma



    • Arises from floor of 4th ventricle


    • “Plastic” tumor squeezes out lateral recesses, foramen of Magendie


    • Intratumoral cysts, hemorrhage common


    • 2/3 are infratentorial within 4th ventricle


    • Heterogeneous, enhancing mass


  • Pilocytic Astrocytoma



    • Cyst with enhancing mural nodule


    • Typically cerebellar hemisphere rather than intraventricular


    • 60% are cerebellar; 30% optic nerve/chiasm


  • Brainstem Glioma, Pediatric



    • Intrinsic to brainstem, not 4th ventricle


    • May be dorsally exophytic, project posteriorly into 4th ventricle


Helpful Clues for Less Common Diagnoses



  • Subependymoma



    • Inferior 4th ventricle, obex (60%)


    • Middle-aged, older adults


    • T2 hyperintense lobular mass


    • No or mild enhancement is typical


  • Choroid Plexus Papilloma



    • 40% involve 4th ventricle (posterior medullary velum), CPA, & foramina of Luschka


    • 4th ventricle common location in adults


    • Lateral ventricle more common in child


    • Lobular, vibrantly enhancing mass


  • Neurocysticercosis



    • Convexity subarachnoid spaces most common location


    • May involve cisterns > parenchyma > ventricles


    • Intraventricular cysts are often isolated, 4th ventricle most common


    • Imaging varies with stage, host response


  • Epidermoid Cyst



    • Congenital epithelial inclusion cyst


    • 90% intradural, primarily in basal cisterns



      • CPA: 40-50%; 4th ventricle 15-20%


    • Nonenhancing, lobular, extra-axial mass


    • Follows CSF on all sequences except FLAIR & DWI


  • Hemangioblastoma



    • Intra-axial posterior fossa mass with cyst & enhancing mural nodule abutting pia


    • Associated with von Hippel-Lindau disease


    • 90-95% posterior fossa: 80% cerebellar hemispheres; 15% vermis, 5% other (medulla, 4th ventricle)


    • 7-10% of posterior fossa tumors


    • 60% cyst & “mural” nodule; 40% solid


  • Metastasis, Intraventricular



    • Intraventricular metastases often involve choroid plexus



    • Gray-white junction lesions most common


    • Primary tumor often known


  • Atypical Teratoid-Rhabdoid Tumor (ATRT)

Tags:
Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Fourth Ventricle Mass

Full access? Get Clinical Tree
Get Clinical Tree app for offline access