D.D.Intra axial versus extra axial Lesion

Here you are looking to a case of cerebellar lymphoma, look carefully to the right cerebello pontine angle, it is not widened even it is less in diameter than the left one suggesting that this lesion is in the cerebellum and not in the cerebello pontine angle.

Here you are looking to a case of cerebello pontine angle lesion on the right side, look carefully to the right cerebello pontine angle(Ambient cistern), it is  widened in diameter than the left one suggesting that this lesion is in the cerebello pontine angle and not in the cerebellum.