1. Spectrum of Intraventricular Neoplasms: Narrowing the Differential Diagnosis
eEdE-85
John K. Fang, MD
Wilson Altmeyer, MD
Bundhit Tantiwongkosi, MD
Achint Singh, MD
Carlos Bazan, MD

2. Disclosure Statement
The authors have no financial interests to disclose.

3. Purpose
To illustrate the spectrum of intraventricular neoplasms through discussion of their histologic origin and narrow the differential diagnosis through analysis of key imaging and demographic characteristics.

4. Approach and Discussion
Ventricular histology
Ventricular Wall and Septum Pellucidum
Ependymoma
Subependymoma
Central Neurocytoma
Subependymal Giant Cell Astrocytoma
Choroid Plexus
Choroid Plexus Papilloma
Choroid Plexus Carcinoma
Meningioma
Metastasis
Non-neoplastic intraventricular lesion
Colloid Cyst

5. Histology Ependymal lining (ependymoma)
Cuboidal/columnar cells variable in morphology according to location
Lateral ventricles: ciliated and nonciliated ependymal cells, lack tight junctions
Third ventricle: ventrolateral wall – tanycytes
Extend from ventricular lining to underlying neurophils
Provide neuroendocrine link with CSF

6. Histology
Subependymal lining (subependymoma) – glial subependymal cells subjacent to ependymal lining
Contributes to blood brain barrier
Absent in portions of the third and fourth ventricles – no blood brain barrier
Pineal gland, median eminence, subfornical organ, area postrema, subcommissural organ, organum vasculosum of the lamina terminalis, and posterior lobe of the pituitary gland

7. Histology Septum Pellucidum
Shared origin with corpus callosum and limbic system
Lined with ependyma
Glial cells and neuronal precursor cells (central neurocytoma)

8. Histology Choroid Plexus
Invaginations of pia mater about highly vascular stalks (metastasis)
Continuous with ependymal lining
Arachnoid cap cells (from arachnoid granulations) may be trapped during development (meningioma)

9. Ependymoma: Imaging Glial tumors arising from ependymal wall
CT: Hypo to iso-attenuating
Coarse calcifications typical (40-80%)
May extend into parenchyma or through foramina

10. Ependymoma: Imaging T2: Iso-hyperintense with cystic components
Occasional intratumoral hemorrhage
Restricted diffusion: variable correlating with cellularity

11. Ependymoma: Imaging
T1: Iso-hypointense
Gd+: Heterogenous enhancement

12. Ependymoma: Categorization
Supratentorial (40%) vs infratentorial (60%)
Slightly less than 50% intraventricular
Most common in children/young adults
Infratentorial: 6 years
Supratentorial: years
Clinical presentation: depending upon location
Supratentorial: headache and seizure
Fourth ventricle: hydrocephalus

13. Subependymoma: Imaging
Glial tumors arising from subependymal layer
CT: Iso-hypoattenuation
Calcification possible but less common (30%)
T1: Iso-hypointense
Gd+: Most little to no enhancement

14. Subependymoma: Imaging
T2: Hyperintense
Typically no invasion of surrounding tissues
No abnormal signal of periventricular tissues

15. Subependymoma: Categorization
Most common in fourth ventricle (50-60%) and lateral ventricles (30-40%)
Typically middle-aged males (2.3:1, M:F)
Asymptomatic (60%) and incidental

16. Central Neurocytoma
Arise from neuroprogenitor cells within septum pellucidum (“central”)
CT: Hyperattenuating
Calcifications (50%)
Cystic changes common

17. Central Neurocytoma: Imaging
T2: Hyperintense
Bubbly cystic appearance

18. Central Neurocytoma: Imaging
T1: Isointense
Gd+: Moderate to strong enhancement

19. Central Neurocytoma: Categorization
“Central” neurocytoma reserved for intraventricular origin, 50% lateral ventricle
Similar tumors may occur elsewhere
Mean patient age 29 (20-40)
Clinical presentation: hydrocephalus and increased intracranial pressure

20. Subependymal Giant Cell Astrocytoma
Subependymal Giant Cell Astrocytoma (or Tumor)
Arise from neuroglial cells
Found associated with tuberous sclerosis
Numerous subcortical tubers

21. Subependymal Giant Cell Astrocytoma
Arise near Foramen of Monro
CT: Hypo-isoattenuation
Calcification variable
T1: Hypo-isointense
T2: Iso-hyperintense
Gd+: Avid enhancement

22. Subependymal Giant Cell Astrocytoma
All occur in lateral ventricle near Foramen of Monro
Associated with children with tuberous sclerosis

23. Choroid Plexus Papilloma: Imaging
Arise from choroid plexus epithelium
Typically centered in atria of lateral ventricles or fourth ventricle
CT: Iso-hyperattenuation
Calcification (24%)

24. Choroid Plexus Papilloma: Imaging
T2: Iso-hyperintensity
Papillary or lobular contour
Flow voids common
Often demonstrate extraventricular extension and edema
Often associated with hydrocephalus
Hydrocephalus

25. Choroid Plexus Papilloma: Imaging
T1: Iso-hypointense
Gd+: Avid enhancement

26. Choroid Plexus Papilloma: Categorization
Lateral ventricle (50%) and fourth ventricle (40%)
Lateral ventricle: 50% are < 10 years of age
Fourth ventricle: Wide range (0-50 years)
Clinical Presentation: Hydrocephalus and increased intracranial pressure

27. Choroid Plexus Carcinoma: Imaging
Typically infants, young children
Similar appearance to choroid plexus papillomas
More invasive and irregular contour
Difficult to differentiate from choroid plexus papilloma on imaging alone

28. Choroid Plexus Carcinoma: Imaging
T2: Heterogenous attenuation
Vasogenic edema and mass effect

29. Choroid Plexus Carcinoma: Imaging
Gd+: Avid enhancement
Can see invasion of brain parenchyma

30. Choroid Plexus Meningioma
Arising from arachnoidal cap cells
Trapped in choroid plexus during embryogenesis
CT: Hyperattenuating
Calcifications common (50%)
Radiographics, Smith et al..

31. Choroid Plexus Meningioma
T1: Iso-hypointense
T2: Iso-hyperintnese
Gd+: Avid enhancement
May exhibit periventricular edema
Varying degrees of ventricular dilation

32. Choroid Plexus Meningioma
Most common in atria of lateral ventricles
Less common third then fourth ventricles
Female predominance (2:1, F:M)
Adults: years
Clinical presentation: Increased intracranial pressure – usually large size at diagnosis

33. Intraventricular Metastasis
Atrial mass in choroid plexus
May be indistinguishable from choroid plexus tumors
CT: Iso-hyperattenuation
T1: Iso-hypointense
T2: Variable - hyperintense
Gd+: Avid enhancement
Adults > children
Renal and lung metastasis most common
Known primary neoplasm raises concern for metastasis

34. Non-neoplastic Intraventricular Lesion
Colloid Cyst
Mucin containing cyst
Third ventricle at foramen of Monro
CT: hyperdense
T1: hyperintense
T2: variable
Gd+: no enhancement
Associated with hydrocephalus if obstructive

35. Summary Demographics CT MR and Gd+ Key Location and Characteristics
Ependymoma
4th ventricle: 6 years
Supratentorial: 18-24
Isoattenuation
Calcifications 40-80%
Heterogenous; intense enhancement
60% 4th ventricle
Extraventricular extension common
Subependymoma
Middle aged males
Iso-hypoattenuation
Calcifications 30%
Hydrocephalus 85%
T1: hypo; T2: hyper
Variable, usually little enhancement
Majority in 4th and lateral ventricles
Rarely extraventricular
Central Neurocytoma
20-40 years
Hyperattenuation
Calcifications 50%
T1: hyper; T2: heterogenous
Moderate to strong enhancement
50% lateral ventricles and septum pellucidum
SEGA
Children with tuberous sclerosis
Calcified nodule
T1: hypo
T2: heterogenously hyper
Intense enhancement
Lateral ventricle near foramen of Monro
CP Papilloma
Lateral: 50% < 10 years
4th: 0-50 years
Iso-hyperattenuating
Calcification 24%
Hydrocephalus
T1: Iso-hypo
T2: variable hyper
50% lateral ventricles (atria)
40% 4th ventricle
Prominent lobulations
CP Carcinoma
Infants/young children
Heterogenous
Vasogenic edema
Aggressive, brain invasion
Meningioma
Adults years
Calcification 50%
T2: Iso-hyper
Atrial mass / choroid plexus
Metastasis
More common in adults
Iso-hyperattenuation
Primary lesions: lung / renal

36. References
Koeller, Kelly and Glenn Sandberg. Cerebral Intraventricular Neoplasms: Radiologic-Pathologic Correlation. Radiographics. 22:
Smith, Alice et al. Intraventricular Neoplasms: Radiologic-Pathologic Correlation. Radiographics. 33:
Mortazavi, MM et al. The ventricular system of the brain: a comprehensive review of its history, anatomy, histology, embryology, and surgical considerations. Childs Nerv Syst. 30:
Sarwar, Mohammad. The Septum Pellucidum: Normal and Abnormal. AJNR. 10: