MON-071 Macroprolactinoma And Carotid Body Paraganglioma In A Young Patient With SDHB Mutation

Abstract Disclosure: N.V. Jumalon: None. A. Hosford, MD: None. T. Duro: None. C. Lovato: None. Background: The Succinate Dehydrogenase Complex (SDH) gene is responsible for coding the four subunits (A, B, C, D) that comprise Complex II of the electron transport chain making it a key component for ATP production. In patients with SDHB gene mutations, there is an increased risk for development of pheochromocytoma and paragangliomas (PPGLs) and nonsyndromic paragangliomas (PGLs). Other pathologies associated with SDHB gene mutations include renal cell carcinomas, gastrointestinal stromal tumors, and, in rare cases, pituitary adenomas (PAs). Clinical Case: A 22 year-old male patient presented to the ED for worsening peripheral vision loss over the course of 2 weeks in the setting of worsening intensity and frequency of headaches over the course of several months. He denied symptoms of fatigue, generalized weakness, galactorrhea, constipation, cold/heat intolerance, and poor oral intake. Physical exam revealed bitemporal hemianopsia. Family history was significant for a carotid body tumor in a paternal aunt. MRI of the brain/stem on admission showed a 3.3 cm sellar/suprasellar mass causing regional mass effect with displacement of the optic apparatus and masslike enhancement at the region of the right carotid bifurcation. The patient’s prolactin was markedly elevated at 1,132 ng/mL (n 4-15 ng/mL) with normal IGF-1. Serum cortisol and free T4 levels were normal. The patient was emergently taken for transnasal resection with pathology showing a PA which stained positive for prolactin. The patient’s prolactin normalized at 5.5 ng/mL on postoperative day 3 with immediate clinical improvement of peripheral vision. Neck CT with contrast confirmed the presence of a right carotid body PGL with mild mass effect on the airway. Plasma fractionated metanephrines were normal. Given the presence of the PA and carotid body PGL, the patient was evaluated for hereditary syndromes, which was positive for the SDHB gene mutation. The patient’s right carotid body tumor was resected and pathology showed an SDHB-deficient PGL. The patient will be followed closely with yearly plasma fractionated metanephrines and full body MRIs every 2-3 years. Clinical Lessons: This is a rare case of a young patient with a PA and carotid body PGL in the setting of SDHB mutation. Current studies suggest that pathogenic variants in the SDHB gene are loss-of-function mutations that confer a lifetime risk of 22% to 47% for PPGLs. Research regarding the relationship between PAs and SDH gene mutation is limited, however, one retrospective cohort study found a greater association between SDH mutation and patients with PA who also have a family history of PPGL. Some studies also suggest PAs in patients with SDH mutations can be more aggressive and less responsive to standard therapy. This case highlights the importance of close follow up for these patients as well as obtaining a thorough family history to evaluate for coexisting PPGLs. Presentation: Monday, July 14, 2025