Is Cavernous Sinus Space Invaded or Not?

The diagnosis of cavernous sinus invasion by secreting PitNETs is fundamental for patient management. Full cavernous sinus invasion by PitNET is obvious. The lateral wall of the cavernous sinus is swollen. The normal anterior pituitary is not shown between the pituitary adenoma and the cavernous sinus. Veins are no longer visible and the cavernous sinus is replaced by a solid tissue whose characteristics are similar to those of the intrasellar compartment of the adenoma. If cavernous sinus invasion is limited, the diagnosis is much more complex and the classical Knosp’s landmarks could be in default. The ultimate proof of invasion would be the demonstration of a tear of the thin dural wall separating the cavernous sinus space from the pituitary fossa on coronal or axial T2W images. A unilateral triangular posterolateral tumoral extension seen on axial sequences attests to the extreme thinness and fragility of the posterior part of the internal dural wall.