SAT-077 Pituitary Adenomas in Multiple Endocrine Neoplasia Type 1

Abstract Disclosure: Y.B. Omotosho: None. N.U. Vikram: None. E.C. Wright: None. R. Tora: None. V. Dola: None. W. Abbas: None. N. Biassou: None. T. Massie: None. L. Bliss: None. P. Chittiboina: None. L.S. Weinstein: None. W.F. Simonds: None. S. Jha: None. Background: Patients with Multiple Endocrine Neoplasia Type 1 (MEN1) are genetically predisposed to developing pituitary adenomas. However, there is no evidence to guide surveillance testing in this cohort. Functional pituitary adenomas (PAs) can be monitored through laboratory assessments, whereas non-functional PAs require imaging unless they grow large enough to cause hypopituitarism, visual impairment, or other neurological symptoms. The current expert consensus is to obtain a pituitary MRI every 3-5 years. This study aims to examine the natural history of MEN1-related pituitary adenomas, particularly non-functional ones, to inform surveillance strategies. Methods: In this longitudinal cohort study, we identified 320 patients with genetically confirmed disease and available findings from pituitary MRI. Statistical analysis was performed in R studio. A p-value <0.05 defined statistical significance. Results: Of the 320 patients, 161 were females (50.3%) and 159 males (49.7%). Mean age at diagnosis was 33 ± 16 years, and mean age at last follow up was 47± 16 years. 182/320 patients (57%) had PAs. 78/182 (43%) patients were diagnosed with PAs at the time of diagnosis of MEN1. There appeared to be equal prevalence of both functional and non-functional PAs with 87/182 (48%) patients having functional PAs [78/87 (90%) prolactinomas, 2/87 (2%) GH-secreting and 8/87 (9%) ACTH-secreting] and the remaining 95/182 (52%) patients having non-functional PAs. 21/95 (24%) patients with non-functional PAs needed an intervention (medical or surgical) during their follow-up. Patients with macroadenomas were more likely to need an intervention (17/21, 81%) than patients with microadenomas (4/74, 5%), p <0.0001. Of the 21 patients with non-functional PAs needing an intervention, 11/21 (52%) had associated biochemical abnormalities on pituitary function testing and 18/21 (86%) had associated symptoms. There was only one patient with no associated symptom or abnormalities on pituitary function testing. The cumulative incidence of patients with non-functional adenomas requiring an intervention was 6% (CI: 2-14%) by age 35 years. Spaghetti plot analysis of tumor volumes for non-functional PAs without any intervention demonstrated a flat curve indicating minimal annual growth. Discussion: We observed a similar frequency of functional and non-functional pituitary adenomas (PAs) in MEN1. The 24% intervention rate for non-functional adenomas in this cohort aligns with reports that 25-50% of sporadic non-functional PAs show tumor growth or visual field deterioration. Notably, 20/21 cases of non-functional PAs requiring intervention were associated with abnormalities in pituitary function tests or reported symptoms. This finding suggests that surveillance imaging for MEN1-related PAs can be used sparingly, with greater reliance on symptom history and pituitary function testing. Presentation: Saturday, July 12, 2025