Computed tomography and magnetic resonance imaging characteristics of giant pituitary adenomas

Purpose: The purpose of this study was to characterize the computed tomogra phy (CT) and magnetic resonance (MR) imaging features of giant pituitary ad enoma (GPA) and to demonstrate the pathways of the spread of GPA. Methods: CT and/or MR imaging scans of 356 patients evaluated preoperativel y for single pituitary tumor were reviewed. Fourteen tumors (4%) fulfilled the radiologic criteria for GPA. There were 10 male and four female patient s, ranging in age from 22 to 71 years (mean, 52 yr). We retrospectively rev iewed the CT and MR imaging scans of these patients to characterize tumor a ppearances and identify the pathways of turner extension. Results: Thirteen tumors (93%) extended upward to the suprasellar cistern, and/or hypothalamus and third ventricle. Intrasellar extension through the sellar floor and sphenoid sinus to the skull base, or to the ethmoid sinus or the nasopharynx, was identified in seven patients (50%). Eight patients (57%) had lateral invasion to the cavernous sinus. Temporal and frontal ext ension was apparent in seven patients (50%) and six patients (43%), respect ively. Five patients (36%) had posterior subtentorial extension to the post erior fossa. Histologically, only two GPAs showed invasive features. There was no correlation among histologic features, pituitary hormone concentrati ons, and evidence of tumor aggressiveness on CT and MRI scans. Conclusions: GPA has the potential for widespread, multi-directional extens ion. Our results indicate that any type of pituitary adenoma, regardless of its endocrinologic activity, may invade surrounding structures. Suprasella r invasion is the most common pathway of tumor spread, followed by intrasel lar, lateral, anterior, and posterior routes.