7576 A Rare and Atypical Presentation of Bladder Paraganglioma in a Patient on Long-Term Left Ventricular Assist Device

Abstract Disclosure: S.D. Leungsuwan: None. S.J. Lee: None. S.D. Lim: None. L. Loh: None. Background: Paragangliomas (PGLs) are rare neuroendocrine tumors arising from chromaffin cells. Capable of producing catecholamines, functional PGLs often cause a myriad of autonomic symptoms and complications, including cardiomyopathy. We report a case of bladder PGL in a patient on Left Ventricular Assist Device (LVAD). Clinical Case: A 64-year-old Chinese Female with a history of non-ischaemic cardiomyopathy on long-term continuous LVAD and Cardiac Resynchronisation Therapy Defibrillator (CRT-D) was admitted for recurrent low LVAD flow <2 Litres per minute and labile mean arterial pressure (MAP) 57-151mmHg. She has been on long-term Nebivolol, Entresto, Hydralazine, and Sildenafil without recent dose adjustment. Workup for acute illnesses was non-contributory. 24-hour urine metanephrine and normetanephrine (NM) were 939nmol/d [normal 400-1500nmol/d] and 33883nmol/d [normal 600-1900nmol/d] respectively. Plasma free metanephrine and NM were 0.37nmol/L [normal <0.33nmol/L] and >10.00nmol/L [normal <0.99nmol/L] accordingly. A review of previous ultrasonography and Computed Tomography (CT) imaging revealed a right adnexal mass indenting the bladder which the patient formerly declined further assessment; adrenal glands were normal. FDG-PET CT was done and showed an isolated focus of increased tracer uptake corresponding with the right pelvic mass. An impression of likely bladder PGL was made. A multidisciplinary team including Cardiology, Anaesthesiology, Interventional Radiology (IR), Urology, Gynaecology, and Endocrinology was convened; the patient was recommended surgical resection of the tumor. Preoperatively, she was started on phenoxybenzamine 10mg BD and advised judicious fluid and salt intake. Nebivolol was continued while hydralazine was stopped. This achieved targets of i) MAP 70-80mmHg, ii) approximately 10mmHg MAP postural fluctuation, iii) sitting and standing heart rates 60-70 beats-per-minute (BPM) and 70-80BPM, and iv) no more than 1 PVC every 5 minutes. Two weeks later, she underwent IR-guided angioembolisation and tumor resection uneventfully. Intraoperatively, the patient had haemodynamic fluctuations requiring dynamic administrations of phentolamine, norepinephrine, epinephrine, vasopressin, glyceryl trinitrate, and sodium nitroprusside. Histopathology was consistent with PGL with intact SDH-A and SDH-B expression. Postoperatively, phenoxybenzamine was discontinued and no recurrent LVAD low flow was noted. Subsequent plans for repeat plasma metanephrines and genetic studies were made. Discussion: This case is the first to report an atypical presentation of PGL with LVAD low flow and labile blood pressure. The significant elevations of urine NM (17.8x upper normal limit) and plasma NM (>10.1x upper normal limit) also underline the concept of fold-elevations and post-test probability of PGL. Presentation: 6/3/2024