Differentiation of large suprasellar masses by evaluation of the superior margin.
Differentiation of suprasellar masses by computed tomography criteria depends on intrasellar extension, patterns of calcification and enhancement, associated bony reaction, and cystic changes. In the case of a homogeneously enhancing suprasellar mass that does not exhibit any of these differentiating findings, separating a suprasellar meningioma from a large suprasellar pituitary adenoma has been quite difficult. We reviewed the computed tomography findings of 42 such tumors. There were 19 meningiomas and 23 pituitary adenomas chosen that had few or none of the commonly applied findings used in differentiation. Evaluation of the superior contour of these masses seems a reliable sign to use in this situation. A single upward convex curve correlated with a meningioma in 15 of 19 cases (78%), whereas a multiple upward convex curve correlated with a pituitary adenoma in 19 of 23 cases (82%). Although some pitfalls were encountered when employing this sign--such as pseudolobulations caused by the adjoining cavernous sinus, dural, or vascular structures--it nonetheless led to the correct diagnosis in approximately 80% of cases.