(17.01) Breast Lesion in a Patient with Paraganglioma – Metastasis versus Fibroadenoma?

A 34-year-old female with history of recently diagnosed type 2 diabetes and hypertension, presented with a 3-month history of abdominal pain, episodic headaches, and dizziness. She was recently hospitalized for diabetic ketoacidosis and hypertensive emergency. She was found to have elevated plasma normetanephrine (9,954 pg/ml, normal 0.0 - 210.1 pg/mL) and metanephrine (620 pg/ml, normal 0.0 - 88.0 pg/mL) levels, and increased 24-hour urine normetanephrine and metanephrine levels (10,952 ug/24 hr, normal 110 - 720; 1,406 ug/24 hr, normal 35 - 278, respectively). Work-up included elevated chromogranin A and normal aldosterone/renin ratio. MRI abdomen revealed 8.1x5.5x 6.7 cm heterogeneously enhancing T2 hyperintense mass abutting the inferior liver, extrahepatic biliary ducts, portal vein, IVC, and celiac trunk with unclear origin, and a left breast mass of 2.5 cm. For functional characterization, a PET-DOTATATE scan demonstrated the same avid mass in the mid to right abdomen and another avid 2.4 cm nodule in the lower outer left breast. Differential diagnoses of the abdominal mass included paraganglioma versus pheochromocytoma. Due to the breast lesion avidity for DOTATATE, there was concern for metastasis from the NET. The patient was started on phenoxybenzamine followed by metoprolol, amlodipine, and insulin prior to surgery. She underwent surgical resection of both masses. The abdominal tumor was located adjacent to but did not involve the adrenal gland. The pathology of the mass was consistent with sympathetic paraganglioma with retained staining for SDHB. Left breast lesion pathology was consistent with fibroadenoma. Post-op, the patient no longer required anti-hypertensive or diabetes medications. Urine catecholamines normalized, and plasma normetanephrines were near normal. 

Discussion : To the best of our knowledge, there have been two cases of metastatic breast cancer from paraganglioma. Few case reports have demonstrated breast fibroadenoma with increased activity on 68Ga-DOTATATE PET/CT and is due to cell surface overexpression of somatostatin receptors by this benign breast tumor. This case emphasizes the need for cautious interpretation of Ga DOTATATE-avid breast lesions that could mimic malignancy in NET patients.