Brain tumors with heterogeneous enhancement

1-Causes:

-Glioma (50% of the brain tumors).

*Astrocytoma.

*Ependymoma.

*Oligodendroglioma.

*Choroid plexus papilloma.

*Pineal body tumors.

-Others.

2-Glioma could be divided into 3 categories:

-Low grade : Affect mainly teens and young adults.

-Anaplastic : Affect middle age.

-Glioblastoma : Elderly patient.

3-Low grades glioma are three types:

-Pilocytic astrocytoma.

*Age incidence: 5-15 years.
*Cyst with an enhancing nodule most common in the cerebellum, less commonly could be seen supra tentorial in the hipocampus leading to epilepsy having the same appearance of infra tentorial lesion.
*Sometimes you see also marginal enhancement with mural nodules enhancement.
*Another sign is leak of the contrast in the cavity of the cyst making a fluid level.


-Sub ependymal giant cell astrocytoma.

*Occurs with tuberous sclerosis( suffer from epilepsy + mental retardation + cutaneous tuber) develops from nodules, always in the lateral ventricle near the foreman of Monroe.
*Age incidence: Teens to 20 years.
*CT:Iso dense or slightly hyper dense with calcification and homogenous enhancement + pathognomonic finding which is presence of other calcified nodules in the ventricular wall + multiple angiomyolipoma in the kidney and liver.


-Pleomorphic xantho-astrocytoma (PXA).

*Age: second decades.
*Seen supra tentorial as a cyst with enhancing nodule, here the nodule should be superficial with surface distribution.
*How we can differentiate PXA from cystic meningioma.
In meningioma, the solid part of the lesion is more greater than the smaller cystic part while in PXA the reverse is seen where the solid part taking enhancement is small while the cystic part is bigger. 
 

4-High grades glioma are also three types:

-Diffuse astrocytoma.

* Young adults to 45 years old.
*It does not take contrast.
*CT:Appears as hypo dense area with no enhancement.
*How to differentiate between it and infarction.
By clinical data in patient with infarction is suffering from hemiplegia while in patient with diffuse astrocytoma is suffering from weakness.
Infarction has a vascular distribution with base of the triangle in contact with surface of the brain.
In case of diffuse astrocytoma and when we inject contrast we can see the vessel supplying the tumor patent while in infarction, it should be obstructed.
Lastly, if the patient did a CT and MRI at same time, the tumor in MRI is seen more in size than that seen in CT. 



-Anaplastic astrocytoma.

* As diffuse astrocytoma, but differs in that if it is given contrast, it give appearance of little number of enhanced dots.

-Glioblastoma multiform.

*Butterfly configuration, extends across the midline in 75% of cases.
*Giving heterogenous or marginal enhancement (D.D.from brain abscess where the former shows irregular thickened marginal enhancement while the latter shows regular marginal enhancement).
*Very common to find bleeding within glioblastoma multiform (Hyper intense in T1 and T2).
*How to differentiate between the following:
T1:CSF is black while the lesion is hypo intense.
T2:CSF is white while the lesion is hyper intense.
FLAIR :CSF is black while the lesion is hyper intense.
*Making brain edema in 90% of cases.

4-Infiltrating glioma ( Gliomatosis cerebri ):

- Differs between infiltrating and diffuse gliomas is in that in case of infiltrating glioma no margin could be seen by any modality.
-In case of infiltrating glioma you can suggests its presence only by its mass effect with disappearance of the white grey matter inter phase.
-It does not enhances.
-D.D. between it and sub acute sub dural hematoma:
Look to the white grey matter inter phase, if it is maintained, it will be sub acute sub dural hematoma, if it is not seen, it will be infiltrating glioma.


5-Oligodendroglioma:


-It is glioma containing calcium (considered one of the low grade gliomas).
-A mass inside the brain containing calcium, should be considered a oligodendroglioma after exclusion of vascular abnormalities.

6-Multicenteric glioma:

-Glioma causing multiple lesions in the brain mimicking metastases.
-Spectroscopy can be the only way to differentiate between multicenteric glioma and metastases.
-The second way to differentiate is presence of history of primary.
-Metastases are far more common than multicenteric glioma.
-Metastases can produce any type of enhancement (homogenous, heterogenous or marginal enhancement).
-Metastases could be single in about 50% of cases(could be diagnosed by known primary and extensive edema surrounding it).
-Most common site in the body to metastasize to the brain is bronchogenic carcinoma.
-Metastases could be cystic as pilocytic astrocytoma, here they can be differentiated by multiplicity and known primary.