PSUN375 What Blindness and Paraganglioma Have in Common? A Rare Case of Paraganglioma Syndrome

Abstract

Abstract Background Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors with an annual incidence in the U.S. of 500-1600 cases per year. Approximately 30-35% of PPGLs harbor germline mutations, while 35-40% are due to somatic mutations. Recent studies have identified the association between somatic mutations of the hypoxia-inducible factor 2 alpha (HIF2A) gene and a new syndrome of PPGLs associated with congenital polycythemia. Patients present with recurrent PPGLs, congenital malformation of intracranial veins, malformation of macula and retina, and type I Chiari malformations. Case A 44-year-old man with history of in-utero stroke, congenital blindness, polycythemia and spinal stenosis had an incidental para-aortic lesion found during workup of back pain. He experienced episodic palpitations associated with diaphoresis, headache and uncontrolled hypertension for the past eight year. There was no family history of neuroendocrine tumors. Dedicated abdominal computer tomography with contrast showed a right adrenal enhancing lesion measuring 1.4×1.2 cm and a conglomerate of heterogenous enhancing periaortic lesions measuring up to 5 cm in the mid-abdomen. Biochemical work up revealed plasma free normetanephrine of 27.5 nmol/L (0.00-0.89) and plasma free metanephrines of 0.49 nmol/L (0.00-0.49). Gallium 68 DOTATATE scan showed multiple avid retroperitoneal lesions measuring up to 4.4 cm and an avid right adrenal nodule. He underwent right adrenalectomy and para-aortic lesion resection with perio-operative alpha blockade. Pathology confirmed synchronous pheochromocytoma (1.5 cm, Ki-67< 1%, with capsular and periadrenal fat invasion) and paraganglioma (9.3 cm, Ki-67 < 1%, with lymphovascular invasion and one out of nine lymph nodes positive for metastatic disease). Post-operatively, his metanephrines normalized and a six-months positron emission tomography scan showed no evidence of disease. Genetic testing has been delayed. Discussion This case illustrates a rare syndrome of PPGLs, congenital blindness, and polycythemia, likely due to somatic mutations of HIF2a. HIF is an alpha/beta heterodimer. HIF2a becomes a transcription factor after dimerization with HIF2b. Any mutations that stabilize HIF protein leads to transcription of hypoxia inducible genes resulting in angiogenesis, polycythemia, and tumorigenesis. In our patient, we suspect the stroke in-utero may have been related to abnormal intracranial angiogenesis and/or polycythemia. Recognition of this syndrome and lifelong surveillance is imperative due to risk of recurrence of PPGL. Targeted therapies such as a HIF2a inhibitor have been proposed and trials are ongoing. Our patient remains disease free on radiographic and biochemical surveillance. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.