Homogenous enhancement

Homogenous enhancement:

This includes the following

A-Meningioma.

B-Others including.

-Lymphoma.
-Ependymal giant cell astrocytoma.

Click diagram to enlarge

1-Any lesion causes homogenous enhancement in the brain considered it meningioma and put it on the top of the list.

2-To be sure that this lesion is meningioma, the lesion should be adherent to the meninges (which means adherent to the bone).

3-Radiological signs for diagnosis of meningioma.

The most important signs are

-Homogenous enhancement.
-Dural base.
-Bone sclerosis.

The less important are

-Dural tail.
- Calcification 10-20%.
-Brain edema 40%.


4-Sites of origin of meningioma:


-Convexity meningioma.
-Falcine meningioma.
-Para sellar meningioma, it can cause what is known as vascular encasement which leads to cuffing of internal carotid artery, this sign can differentiate radiologically between meningioma and  para sellar extension of the pituitary macro adenoma in which the former cause vascular encasement while the latter does not cause it.
-Sub frontal meningioma in which it is adherent to the floor of the anterior cranial fossa.
-Multiple meningioma.
You must discriminate between it and multiple metastases which is the most famous lesion could be seen multiple in the brain or any where in the body.
To differentiate between both, the patient should have first of all a history of a primary malignant lesion then you look to every lesion in the brain of the patient, every lesion should has a direct contact to the meninges to say that these lesions are all meningioma, if one of these lesion is not adherent to the meninges, you must diagnose all these lesions as metastases untill prove other wise.
-Intra ventricular meningioma, here there is no meningeal cells, but meningioma here arising from ependymal cells present in choroid plexus, so it is almost always arising from the site of choroid plexus more common on the left side.
Most common lesions arising from ventricles are choroid plexus papilloma(85% arise before age of 5 years) and ependymoma.
D.D.between choroid plexus papilloma and meningioma arising within ventricle(see the next diagram).

Click diagram to enlarge

  -Intra osseous meningioma en plaque, which needs D.D.from fibrous dysplasia which are both appears as osteoblastic bone lesion in the bone of the orbit causing eye proptosis.

5-Important rule:


-Meningioma, as mentioned above, could contains calcium which give hypo intense signal in T1 and T2 with no enhancement.
-Also, it contains vessels, which appears black in T1 and T2 with no enhancement.
-When meningioma becomes larger in size, its central part will be necrotic which appears as hypo intense in T1 and hyper intense in T2 which does not enhance.
-So if the meningioma you deal with, has all these three items and after you gives contrast, the vessels and the calcium will be seen as linear and dot areas (respectively) of hypo intensity in T1 and T2, while the central necrotic area will be seen in T1 as hypo intense area while in T2 it will seen as hyper intense area. In these case do not say that this lesion is not meningioma because it does not give homogenous enhancement, do not account that as heterogenous enhancement but you should accounts it as homogenous enhancement.


6-Cystic meningioma:


-Cystic meningioma means that the meningioma has a peripheral cystic area.
-This cystic component should be in the periphery of the lesion(like a cap) and not in the center.


B-Others:


-If The lesion has a homogenous enhancement and does not gives a dural base, so it is not a meningioma, we go to the other differential and almost the only one which is lymphoma.
-Dural base means good wide contact with meninges and not just attaching it.
-Lymphoma accounts for 1% of brain tumors while  meningioma accounts for 15%, so meningioma is most common than lymphoma in clinical practice, so I must be sure that the lesion is not of wide dural base to exclude meningioma and diagnose lymphoma.
-Mean age of lymphoma is 50 years, while it can be seen in children with immune compromised state.
-Very famous rule nowadays is in the patient receiving chemotherapy in cases of malignancy such as bronchogenic carcinoma, the most famous second primary malignancy could affect this patient is lymphoma(Double primary malignancy).
-Radiological appearances of lymphoma:
*Homogenous enhancement.
*Peri ventricular in location.
*Can cross the mid line.
*Little edema and mass effect with no calcification.