What is you favoured diagnosis? How sure can you be?
A meningioma is by far the most likely diagnosis, and you can be very confident in the diagnosis.
Why is it important to make this diagnosis preoperatively if possible?
A lesion such as this would be more challenging to completely remove with a transsphenoidal approach, although this approach is being used by many neurosurgeons, rather than the more traditional craniotomy based approach. This lesion, were it to be removed transsphenoidally generally requires more bone removal and a bigger opening into the subarachnoid space than for an adenoma. Therefore reconstruction is more challenging, usually necessitating a nasal septal vascularised flap.
What specific features are helpful in this case?
The normal pituitary fossa and normal pituitary tissue can be seen separate to the mass (in fact the infundibulum can be seen surrounded by the mass on post contrast sagittal images). The dura of the diaphragma sella is pushed down, further evidence of the suprasellar origin. In addition the mass demonstrates dural tails, also helpful.
The sella and suprasellar mass lesion demonstrates homogenous and prominent contrast enhancement, measures 20 x 29 x 30.4 mm, is centred on the tuberculum sella, extends across the pituitary fossa, bulges into the prepontine cistern, interpeduncular cistern, elevates the floor of the third ventricle, and optic chiasm and nerves, and displaces the anterior cerebral arteries (which have a close contact with the superior margin of the tumour). Anteriorly extends along the planum sphenoidale, with a dural tail of enhancement.
Differential enhancement separates the mass from the contiguous pituitary which is seen inferiorly within the sella. A tongue of tumour extends into the right optic canal. No hydrocephalus. Mild sulcal ventricular prominence within age normal range.