Learning objectives
Aetiology and types of CNS Lymphoma - Primary,
Secondary and Angioinvasive.
Characteristic findings and locations on CT and MR imaging.
Tips for diagnosis.
New techniques used in the diagnosis of CNS Lymphoma.
Background
CNS lymphoma may be Primary (PCNSL),
Secondary or Intravascular (Angiocentric.)
PCNSL accounts for 1-5% of brain tumours.
There is an increased risk of secondary CNS involvement in the immunocompromised host.
(1)
Subtypes of CNS Lymphoma:
1.
Primary (PCNSL)
• 1-5% of brain tumours (2)
• 1% NHL’s
2.
Secondary to systemic lymphoma.
• Higher risk in NHL than Hodgkins lymphoma.
• Increased risk secondary CNS involvement in immunocompromised.
• 2/3 leptomeningeal metastases.
(3)
• 1/3 parenchymal metastases.
(3)
3.
Intravascular (Angiocentric) lymphoma
• Malignant lymphoid...
Findings and procedure details
1.
Primary CNS Lymphoma
Within brain parenchyma.
Characteristic appearance due to hypercellularity,
disruption of BBB.
Predilection for periventricular WM / superficial regions,
basal ganglia,
ventricular/meningeal surfaces.
(5,6)
Detection of enhancement along perivascular spaces on MR imaging should put PCNSL at the top of the differential diagnosis,
withsarcoidosis representing the only other consideration.
Increased risk with immunodeficiency.
- CT findings:
Iso/hyperattenuating dense lesions.
(7)
Marked contrast enhancement.
- MRI findings:
T1: Iso/hypointense
T2: Iso/hyperintense.
Immunocompromised: Irregular enhancement common.
(3)
Immunocompetent: Homogenous avid enhancement.
(3)
PCNSL in...
Conclusion
Learning Points
Contrast enhanced MR is modality of choice.
1.
PCNSLs
Almost all have parenchymal lesions.
Dense on non contrast CT.
Predilection for periventricular,
basal ganglia,
leptomeningeal surfaces.
Immunocompetent: usually solitary,
homogenous avid enhancement.
Immunocompromised: multifocal,
irregular,
often ring enhancement.
2.Secondary CNS lymphoma
2/3 leptomenigeal,
1/3 parenchymal
Parenchymal difficult to differentiate from PCNSLs.
3.
Angioinvasive Lymphoma
Rare.
Mimics vasculitis - T2 hyperintense infarct like lesions in non-vascular territorieswith restricted diffusion.
Perivascular linear enhancement.
References
1.
Haldorsen IS,
Krossnes BK,
Aarseth JH,
et al.
Increasing incidence and continued dismal outcome of primary central nervous system lymphoma in Norway 1989 –2003: time trends in a 15-year national survey.Cancer 2007;110:1803–14 6.
2.
Van der Sanden GA,
Schouten LJ,
van Dijck JA,
et al.
Primary central nervous system lymphomas: incidence and survival in the Southern and Eastern Netherlands.
Cancer 2002;94:1548 –56
3.
I.S.
Haldorsen,A.
EspelandandE.-M.
Larsson et al.
Central Nervous System Lymphoma: Characteristic Findings on Traditional and Advanced Imaging.
American Journal of NeuroradiologyJune...
