SAT-449 Retrospective Study in Giant Adenomas (GA): Our Experience

Introduction Giant adenomas (GA) represent 5% of the entire pituitary adenomas (PA) in the reported surgical series. Despite their benign behavior, GA can cause important symptoms and signs due to the possible hyper-secretion of one or more pituitary hormones, involvement of surrounding structures or compression of the pituitary gland. Surgical resection remains the gold standard to decompress the optic chiasm, reduce tumor volume and preserve hormonal function Objective To evaluate the characteristics of GA attended in our hospital in the last 11 years. Materials and methods We conducted a retrospective analysis on clinical records of our patients with PA from January 2007 to April 2018. Results We included 25 patients with GA, who represented 14.4% of our total PA population (n: 173). The mean age was 39.2 ± 17.8 years (r: 15-79). GA were significantly more frequent in men than in women (64% vs. 35.1% respectively, p: 0.004, RR: 1.82). The main initial symptoms were visual defects in 88% of the AG. Invasive tumors (Knosp 4) were significantly more frequent in GA than in PA (81.8% vs. 21.9% respectively, p<0.0001, RR: 3.72). According to the clinical diagnosis, 48% of the GAs were non-functioning adenomas (NFA), while this diagnosis represented only 25.7% of the total PA (p: 0.01, RR: 1.86). Regarding these patients with NFA, both groups had similar age, but GA were more invasive (knosp 4) than PA (RR 2.4; p: 0, 05).80% (20 patients) of GA underwent surgical treatment (48% with transsphenoidal approach), while the rest (5 patients) received cabergoline since they were prolactinomas. The pathology data from 17 out of 20 patients was available: 35.3% gonadotroph, 23.5% lactotroph, 23.5% somatotroph, 5.9% mamosomatotroph, 5.9% corticotroph and 5.9% inmunohistochemically (IHQ) negative.Six patients underwent a 2(nd) surgery, and 3 of them required radiotherapy. Out of the 20 patients operated, 3 died. According to the progression-free survival, calculated by Kaplan-Meier curves, 60% of both GA and PA would be stable after 10 years. The mean remission time of GA (n: 18) was 7.2 years (r:1 month-9,5ys). The mean follow-up period was 3.1 ys (r: 1 month-9,5ys). Conclusion The frequency of GA (14.4%) is slightly higher than the reported in literature. GA were predominant in males, similarly to the reported data. As expected, the visual field defect was the main initial presentation. The GAs were more invasive according to the Knosp classification. Clinically, NFA were the most frequent, similar to that reported in other studies, and the great majority resulted LH and FSH + in IHQ. In spite of the great diameters that the GA can reach, their behavior does not seem to differ from the rest of the PA in terms of their slow growth capacity and evolution. In our experience, these tumors treated in a high complexity center have a progression-free survival similar to that of PA.