Meningioma

1-Meningioma of the cerebello-pontine angle is an extra axial lesion causing widening of the ambient cistern on the same side.

2-It has all the characters of the meningioma anywhere in the body.

3-Extra axial lesion sited on the dura (dural base) with dural tail.

4-Shows homogenous enhancement.

5-Shows calcium.

6-Causes hyper ostosis of the near bone.

7-D.D. between it and acoustic neuroma

-Acoustic neuroma is 90% while meningioma is 5% of the total lesions of cerbello-pontine angle lesions.

-So every time you find a homogeneously enhancing lesion in the cerebello-pontine angle, you must try to diagnose it as a neuroma by looking for the presence of intra canalicular part of the lesion.

-Not all the acoustic neuroma having intra canalicular extension, so it will appears identical to meningioma, here we can differentiate by the following

*By clinical where the patient with the former is suffering from sensory neural hearing loss while in the latter is complaining from symptoms of increased intra cranial tension.

*By increasing the size of the lesion, in the former the enhancement will be heterogenous while in the latter will be still homogenous.

*Acoustic neuroma does not contain calcium usually while meningioma usually contains calcium.

*Acoustic neuroma destruct surrounding bone while meningioma increased density and size of the bone.

-Look to the basilar artery and be sure you can define it to differentiate between aneurysm and meningioma as both gives intense homogenous enhancement. If you can see the artery, so the lesion is not an aneurysm.
-Meningioma in the CPA could be extend via skull foramina to reach para-sellar area, so it appears with two components, one in the CPA and the other is in the para-sellar area.
-D.D.of the previous appearance is meningioma and trigeminal neuroma. 

A diagram showing D.D.of a mass seen in the CPA space and extending in the para sellar space area