MON-488 Metastatic Paraganglioma With a Supraglottic Laryngeal Primary in a Patient With an SDHA Pathogenic Variant

Abstract Disclosure: T.D. Cubb: None. C.M. Skefos: None. R.P. Goepfert: None. M.D. Williams: None. C. Jimenez: None. Introduction: The succinate dehydrogenase (SDH) complex is a tumor suppressor, and pathogenic variants (PV) in its four subunits are associated with hereditary paraganglioma-pheochromocytoma (PPGL) syndromes. <5% of patients with a hereditary PPGL harbor an SDHA PV, with the first case described in 2010. Due to the rarity and lack of long-term data, SDHA PPGL syndrome is not fully understood. We describe a case of a neck PGL with recurrent/metastatic disease in a patient with an SDHA PV. Clinical Case: A 23-year-old male presented with large volume hemoptysis. Laryngoscopy revealed a left supraglottic laryngeal mass that was biopsied and consistent with a paraganglioma (PGL). After preoperative embolization, he underwent debulking surgery (R2 resection) due to proximity to the larynx. Pathology demonstrated a 3.7cm PGL, +chromogranin and synaptophysin staining, intravascular invasion and Ki-67 ≈1%. He had cross-sectional imaging surveillance of the surgical bed with regrowth found at 3 years and 12 years from diagnosis for which he underwent laser resection. At ∼13 years from diagnosis, he had recurrent hemoptysis that necessitated temporary tracheostomy, embolization and additional surgery due to near complete glottic obstruction. Pathology confirmed a 2.7cm recurrent PGL with +margins. Preoperatively 24-hour fractioned catecholamines: norepinephrine 104 (15-80mcg/24hr), epinephrine 2.8 (<21mcg/24hr), dopamine 462 (65-400mcg/24hr). He then established care at our institution. Germline testing showed an SDHA PV called c.667delG. PETCT 68Ga-DOTATE revealed uptake in the surgical bed and lytic skeletal metastases in the spine, sacrum, pelvis and ribs. The patient is asymptomatic from these bone metastases and is currently receiving intermittent IV bisphosphonate with ongoing active surveillance. Conclusion: The penetrance of an SDHA PV is ∼10% by the 7th decade of life; thus, if an SDHA PV is found incidentally via genetic screening the utility is unclear. However, our case highlights the importance of genetic testing in all patients with PPGLs as a hereditary cause will be found in >30%. PPGL with an SDHA PV are historically considered to have low metastatic potential; however, with mounting reports, the risk of malignancy has now been described up to 33% with a predilection for those that arise from the thorax and abdomen. To the best of our knowledge, this is the 2nd case described of an SDHA mutated neck primary PPGL with metastatic disease. This case emphasizes the need to incorporate nuclear medicine functional imaging, as localized cross-sectional analysis will often miss metastatic disease. Despite metastatic disease burden, our patient remains asymptomatic without need for chemotherapy or radiation. Overall, there is need for larger studies to best optimize the treatment and surveillance of patients with PPGLs with an SDHA PV. Presentation: Monday, July 14, 2025