SAT-076 Dual Pituitary Adenomas in an Acromegalic Patient: Diagnostic and Therapeutic Considerations

Abstract Disclosure: B.A. Galizzi: None. M.D. Nascimento: None. R. Natal: None. S. Borigato: None. L.G. Freitas: None. B.S. Soares: None. J.B. Drummond: None. Introduction: Pituitary adenomas are common neuroendocrine tumors, but dual adenomas are extremely rare, accounting for only 2.6% of resected pituitary tumors. Multiple adenomas, especially with hormonal hypersecretion, present significant diagnostic and therapeutic challenges. Case Presentation: A 38-year-old female presented with a 25 kg weight gain over four months, extremity enlargement, and menstrual irregularities. Physical examination suggested acromegaly, but there were no Cushingoid features or galactorrhea. Her medical history included hypertension, managed with Losartan, and prediabetes, controlled with Metformin. In 2019, she experienced a thunderclap headache, prompting an MRI that revealed two pituitary lesions: a left-sided lesion (7.3 × 8.7 × 9.0 mm), hyperintense on T1-weighted imaging, and a right-sided lesion (6.5 × 8.0 × 5.5 mm), hypointense on both T1 and T2. Her IGF-1 was at the upper normal limit, but she lost follow-up and did not pursue further evaluation. At the moment, laboratory tests revealed elevated IGF-1 (329 ng/mL; RV: 63–223 ng/mL) and unsuppressed GH during an oral glucose tolerance test (1.3 ng/mL after 120 minutes; RV < 0.4 ng/mL). Mild hyperprolactinemia (36.8 ng/mL; RV < 18 ng/mL) was noted, suggesting either a non-tumoral cause or a mild co-secretion lesion. A normal calcium metabolism, and a 1 mg dexamethasone suppression test showed a 1.10 μg/dL cortisol level, excluding hypercortisolism. Follow-up MRI in 2024 showed lesions similar to those in 2019, indicating stability. The patient is scheduled for pituitary surgery, with histopathological and immunohistochemical analysis for diagnosis. Discussion: Dual pituitary adenomas are rare, with a prevalence of 0.9% autopsies. The literature remains inconclusive regarding the most common hormonal secretion, with conflicting reports favoring either GH or PRL. A key issue was the suspicion of pituitary apoplexy in 2019. However, the stability of the lesion over years suggests a proteinaceous component rather than hemorrhage. The necessity of resecting both adenomas remains debated. Given the diagnosis, total removal is preferred for remission, but postoperative panhypopituitarism is a concern, particularly in a young patient. Preoperative differentiation between functioning and non-functioning adenomas would allow a targeted surgery. Considering the high prevalence of incidental pituitary adenomas (10–26%), with only 1 in 1000 being clinically significant, preserving a non-secreting lesion to maintain pituitary function would be the optimal outcome. Functional imaging techniques, such as C-methionine PET scans, could aid in this, but their availability is limited. This case emphasizes the need for a multidisciplinary approach, careful surgical planning, and further research into functional imaging tools to guide treatment decisions and avoid unnecessary morbidity. Presentation: Saturday, July 12, 2025