Primary CNS Lymphoma

1. Primary CNS Lymphoma
Neurosurgery & Neuroradiology Conference
Oct 7, 2016
Tanat Tabtieang MD
Department of Radiology
Faculty of Medicine, Chulalongkorn University
King Chulalongkorn Memorial Hospital

2. NECT CECT

3. CECT CECT

4. NECT CECT

5. Imaging findings
• A well defined homogeneously hyperdense lobulated mass
occupying 4th ventricle

6. Homogeneously hyperdense
intracranial tumors
• Medulloblastoma
• Lymphoma
• Germinoma
• >> Hypercellularity

7. Primary CNS lymphoma
• Enhancing lesion(s) within basal ganglia, periventricular white matter
Locations
• 60-80% supratentorial
• Frontal, temporal, and parietal lobes most common
• Deep gray nuclei commonly affected (10%)
• Lesions cluster around ventricles, gray-white matter junction
• Often involve, cross corpus callosum (5-10%)
• Frequently abut, extend along ependymal surfaces
• Posterior fossa, sella, pineal region uncommon
• Spine involvement rare (1%)
• May involve leptomeninges or dura (more common in secondary
lymphoma)

8. CT findings
• NECT
• Classically hyperdense on CT
• ± hemorrhage, necrosis
(immunocompromised)
• CECT
• Diffusely enhancing periventricular
mass in immunocompetent
• Ring in immunocompromised
NECT
CECT

9. MR findings
• T1WI
• Immunocompetent: Homogeneous iso-/hypointense
• Immunocompromised: Iso-/hypointense
• T2WI
• Immunocompetent: Homogeneous iso-/hypointense
• Immunocompromised: Iso-/hypointense
• May be heterogeneous from hemorrhage / necrosis
• Mild surrounding edema is typical
• FLAIR
• Homogeneously iso-/hypointense
• Immunocompromised: Iso-/hypointense
• May be hyperintense
• T1WI C+
• Immunocompetent: Strong homogeneous
enhancement
• Immunocompromised: Peripheral enhancement
with central necrosis or homogeneous enhancement
T1 +C
T1 +C

10. MR findings
• T2* GRE
• May see blood products or calcium as areas of
"blooming" (immunocompromised)
• DWI
• May show restricted diffusion
• Low ADC values compared to malignant glioma
• Minimal ADC lower than glioblastoma
• PWI
• Relative CBV ratios are lower than malignant
glioma
• Relative CBV much lower than glioblastoma
• MRS
• NAA ↓, Cho ↑
• Lipid and lactate peaks reported
DWI

11. MR findings
Immunocompetent
• T1WI: iso-hypointense
• T2WI: iso-hypointense
• (high N/C ratio)
• FLAIR: iso-
hypointense
• DWI, ADC: restricted
diffusion
• T1 +C: strong
homogeneous
enhancement

12. MR findings
Immunocompromised
• T1WI: iso-
hypointense,
• may be
heterogeneous from
hemorrhage/necrosis
• T2WI: heterogeneous
from hemorrhage/
necrosis, mild
surrounding edema
• FLAIR: iso-
hypointense
• T2*GRE: blooming
(blood/calcium)
• T1 +C: peripheral
enhancement with
central necrosis

13. Medulloblastoma
• The most common pediatric posterior fossa tumor
• Malignant, invasive, highly cellular embryonal tumor
• Location:
• Each subgroups arise in distinct regions of cerebellum
• Most common in midline in the cerebellar vermis
• Best diagnostic clue:
• round, dense, 4th ventricle mass
• Leptomeingeal metastasis 33%
• “icing-like enhancement over the brain surface”

14. CT findings
• NECT
• Solid mass in 4th ventricle
• 90% hyperdense
• Ca++ (up to 20%), hemorrhage rare
• Small intratumoral cysts/necrosis in 40-50%
• Hydrocephalus common (95%)
• CECT
• > 90% enhance
• Relatively homogeneous
• Occasionally patchy (may fill in slowly)

15. MR findings
• T1WI: Hypointense to GM
• T2WI: Near GM intensity, or
slightly hyperintense to GM
• FLAIR
• Hyperintense to brain
• Good differentiation of tumor
from CSF in 4th ventricle
• DWI: Restricted diffusion, low
ADC
• T1WI C+
• > 90% enhance (group 4
minimal/no enhancement)
• Often heterogeneous
T1 T2
FLAIR T1 +C

16. MR findings
• Contrast essential to detect CSF dissemination
• Linear icing-like enhancement over brain surface: "Zuckerguss“
• Extensive grape-like tumor nodules common in desmoplastic or
medulloblastoma with extensive nodularity (MBEN)
• May have dural tail and resemble meningioma (cerebellar
hemispheres)
• Contrast-enhanced MR of spine (entire neuraxis)
• Up to 1/3 have subarachnoid metastatic disease at presentation
• Image preoperatively to avoid postoperative false positive: Blood in
spinal canal may mimic or mask metastases

17. Germinoma
• The most common pineal region tumor
• Young patient presents with diabetes insipidus
• Most common: In/near midline (80-90%)
• Pineal region ~ 50-65%
• Suprasellar ~ 25-35%
• Less common: Basal ganglia/thalami ~ 5-10%
• 20% multiple: Most common = pineal with suprasellar ("double
midline atypical teratoma" or bifocal germinoma)
• Age: 90% < 20 yr, M>>F
• Highly cellular, avidly enhancing tumor
• Best diagnostic clue: pineal mass that “engulfs” the pineal
gland >> a central area of calcification

18. CT findings
• NECT
• Lobulated hyperdense mass
• Pineal: Mass drapes around posterior 3rd ventricle or engulfs Ca++
pineal gland
• Suprasellar: "Fat" infundibulum
• Basal ganglia: later iso-/hyperdense lesions without mass effect
• Single calcified spot may be seen on NECT in early stage
• ± cysts / ± hemorrhage (especially in basal ganglia germinomas) / ±
hydrocephalus
• CECT
• Strong uniform enhancement, ± CSF seeding
• Pineal region: Look for posterior 3rd ventricle, midbrain/thalami
infiltration
• Suprasellar: Look for thick stalk, infiltration of 3rdventricular floor,
lateral walls, and anterior columns of fornices
NECT

19. MR findings
• T1WI
• Iso-/hyperintense to GM
• "Fat" stalk/pituitary gland
• Absent posterior pituitary "bright spot“
• Basal ganglia/thalami: 20-33% associated ipsilateral hemiatrophy
• T2WI: Iso- to hyperintense to GM
• Cystic/necrotic foci (high T2 signal)
• Multiple cysts common in germinoma and all GCTs (up to 44%)
• Less common: Hypointense foci (hemorrhage)
• FLAIR: Slightly hyperintense to GM
• T2* GRE: Calcification, hemorrhage "bloom"
• DWI: Reduced diffusion due to high cellularity
• T1WI C+
• Strong, homogeneous enhancement, ± CSF seeding, ± brain invasion
• BG and thalami: Ill-defined enhancement
• Later cystic changes (due to previous hemorrhage and tumor progression)

20. T1 T2 T1 +C
T2T2 T1 +C