SUN-280 Metastatic Pheochromocytoma and Neuroendocrine Breast Cancer in a Young Woman

Abstract Disclosure: C.L. Loughner: None. M.C. Grimes: None. Background: Pheochromocytomas and paragangliomas have been found with increased incidence over the years. In a recent Danish study, the incidence of these tumors has increased to 64.4 per 1,000,000 persons (1). Likewise, neuroendocrine breast cancer is considered rare, though exact numbers have been difficult to elucidate with recent changes in WHO classification (2). Here, we present a young patient with both metastatic pheochromocytoma and neuroendocrine breast cancer without a genetic cause. Clinical case: A 32 year old female presented with headache, nausea, vomiting, hypertension, and hyperglycemia after having a dilation and curettage. BP was 212/110. CT abdomen/pelvis showed a 7.9 x 9.4 x 7.6 cm lobulated heterogeneous mass in the right adrenal bed and a 1.7 cm left breast nodular density. Serum normetanephrines were >10,000 pg/mL (reference: 0-210 pg/mL) and metanephrines were 62 pg/mL (reference 0-88 pg/mL). PET-DOTATATE showed avidity in the right adrenal gland, an aortocaval lymph node, and left retroareolar breast mass. Doxazosin 1 mg nightly and a high sodium diet were started and slowly increased to 5 mg every 12 hours over 14 days preop. Metoprolol tartrate was added after adequate alpha blockade. She underwent open right adrenalectomy and para-aortic, retrocaval lymphadenectomy with pathology consistent with a 7.9 cm pheochromocytoma and one 1.7 cm nodal metastasis. Medications were discontinued without recurrence of hypertension. Four weeks postoperative normetanephrines normalized to 47.5 pg/mL. She then underwent left breast lumpectomy. Pathology revealed a 2.7 cm ER/PR positive invasive neuroendocrine carcinoma with one 0.3 cm lymph node metastasis. Pathology revealed the breast mass was unrelated to her pheochromocytoma. Genetic analysis did not reveal a genetic predisposition for these two malignancies. Patient will begin adjuvant chemotherapy and radiation. Conclusions: Cases of concurrent pheochromocytoma and neuroendocrine breast cancer remain rare. Few case studies show metastatic pheochromocytoma to the breast. Both pheochromocytoma and neuroendocrine breast cancer have been associated with several familial conditions, including Von-Hippel-Lindau, neurofibromatosis 1, and MEN2. However, as demonstrated here, there may be other correlations between these two tumor types not yet elucidated. References: 1. Ebbehoj A, Stochholm K, Jacobsen SF, et al. Incidence and Clinical Presentation of Pheochromocytoma and Sympathetic Paraganglioma: A Population-based Study. J Clin Endocrinol Metab. 2021;106(5):e2251-e2261. doi:10.1210/clinem/dgaa965 2. Tsang JY, Tse GM. Breast cancer with neuroendocrine differentiation: an update based on the latest WHO classification. Mod Pathol. 2021;34(6):1062-1073. doi:10.1038/s41379-021-00736-7 Presentation: Sunday, July 13, 2025