SUN-312 Strikingly Low Prevalence of Pituitary Incidentalomas in Our Hospital

Introduction: Pituitary incidentalomas (PIs) have been reported in 10.6% of autopsies, 4-20% in computed tomography scans (CT) and 10-38% in magnetic resonance imaging (MRI), most of them microincidentalomas(<1cm). They may be have autonomous hormonal activity or impair normal gland function. The frequency of PIs in Uruguay is unknown. We aimed to investigate the prevalence of pituitary incidentalomas in our Hospital. Methods: We retrospectively identified all patients who underwent brain CT and MRI at our hospital over a 1-year period for disorders other than known or suspected pituitary disease. The period covered was from January 1 to December 31, 2017. We reviewed all scans; anamnesis and biochemical evaluation was performed on patients who presented PIs. Results: During this period 3894 patients underwent imaging studies. MRI was performed in 1146 patients, and CT in 2748 of them. Mean age was 53,1 ± 19 years, with similar gender distribution (50.6% women). Most imaging studies where ordered in the emergency department (43%), followed by the outpatient clinics (29%) and inpatient wards (28%). Most common reasons that led to request the image were trauma (20.4%), headaches (11.3%) and stroke (10.9%). We detected two PIs, which accounts for a prevalence of 5 cases per 10,000 individuals per year (0.05%). Both where detected by CT, with a MRI done later to further evaluate them. Final diagnosis was of a vascular aneurysm and a sellar meningioma. Work-up showed a secondary hypothyroidism in the patient with the sellar meningioma. No cases of pituitary adenomas were found. Discussion: We observed a strikingly lower prevalence of PIs than that reported in the literature. In addition, no PIs where found in MRI. Moreover, no pituitary adenoma was discovered. The reasons for these findings are unknown. In our study scans were not focused to the pituitary fossa so small lesions may have been missed. However, Esteves et al(1) reported a prevalence of PIs 5.8% in 1232 patients who had head MRI/CT, not pituitary MRI. In addition, the majority were pituitary adenomas, almost 40% of them microadenomas. Slices of 2-mm thickness were obtained in the scans, similar to imaging techniques used in other studies. Most reports have longer study duration (3-5 years).Our hospital is a teaching hospital where fellows evaluate scans initially, which are then reevaluated by neuroradiologists. This may account for the prevalence found, as sensitivity may be lower when professionals in training evaluate scans. In addition, frequency of pituitary hipointensity areas may decrease as the number of reviewers increase. Furthermore, this low prevalence could be related to difference in population characteristics.Conclusions: We found a very low prevalence of PIs in our hospital. More studies are warranted to further investigate frequency of PIs in our country. (1)Esteves et al. Pituitary. 2015;18(6):777-81.