MON-326 Non Functioning Pituitary Adenomas (NFPA): Sex Related Differences in Presentation, Clinical Features and Outcomes

INTRODUCTION: NFPA are characterized as tumors without a typical hormonal hypersecretion syndrome. They are frequently diagnosed in the sixth decade, by visual field defects, hypopituitarism or incidentally. PATIENTS AND METHODS: retrospective and observational study that included 103 patients with NFPA (60 females) who were seen between 1999 and 2019 in our hospital. We compared and analyzed patients characteristics by sex: reason for consultation, hormonal status at diagnosis, invasiveness of the tumor through MRI, treatments and outcomeRESULTS: out of 103 patients, 58,2% were women (W). Men (M) were significantly older than women (56 vs. 45 yold. p=0,002). The presence of a macroadenoma was similar in both sexes (93%W vs. 94,7% M), however tumor invasiveness was more frequent in men (50% vs. 24,6%). Most men consulted for incidental finding (47,4% vs. 29,8%); most women consulted for symptoms related to the tumor(70% vs 52%): hypogonadism 31,6% W, 13% M; galactorrhea 17% W; visual field defects 21,7% W, 23,7%M, pituitary apoplexy 11,6% M. At baseline hormonal assessment hyperprolactinemia was more frequent (50,9% vs 42%) and higher in women (mean PRL levels 75 ng/ml vs. 37 ng/ml). Hypogonadism was more frequent in men (54% vs 42%) as well as hypopituitarism (15% vs. 10,5%). Surgery was the most used therapy in both sexes (69% M vs. 73%W) but males required more frequently second surgery and radiotherapy than females (15% vs. 5% and 10% vs. 5% respectively). Gonadotropin secreting adenoma was diagnosed in 62% of men and 37,5% by tumor immunohistochemistry, in the 45% of women who presented negative immunostaining the presence of a gonadotrophic lineage is not ruled out, median Ki-67 labeling was low in both sexes (2%). After surgery 66% of men and 37% of women showed tumor remnant > 1cm (p=0,001), tumor regrowth was seen in 38,4% men and 10,4% women (p=0,03). Hypogonadism was greater in men than in women (56% vs 39%). Ninety two percent of men and 60,9% of women developed some degree of pituitary deficiency after surgery (P<0,001). Men showed a higher degree of complete hypopituitarism compared to women (pretreatment 15% vs 10,5%, post treatment 32% vs 13%). CONCLUSION: NFPA in men are usually diagnosed incidentally at an older age, are more invasive at presentation with a higher incidence of pituitary dysfunction. Moreover, they presented with greater rate of tumor regrowth and hypopituitarism after surgery. NFPA in women are diagnosed earlier due to endocrine symptoms, had lower degree of invasiveness with better outcomes after treatment. Sex related differences in NFPA may be associated with the delay in diagnosis, although a more aggressive biology cannot be discarded.