Abstract
BACKGROUND: Pheochromocytomas are catecholamine secreting tumors that arise from the chromaffin cells of the adrenal medulla or from paraganglioma cells, in which case they would be extra-adrenal. They mostly secrete noradrenaline with or without adrenaline. A predominantly dopamine secreting tumor is extremely rare. About 35 cases of abdominal “dopaminomas” have been reported so far most of which are malignant. (1) They are believed to arise from enzymatic deficiency of dopamine beta-hydroxylase which converts dopamine to norepinephrine. CASE: A 65-year-old gentleman, with history of type 1 diabetes and ischemic cardiomyopathy was referred from urology for a pre-operative evaluation after being found to have a 1.4 cms, solid, enhancing right renal mass with an incidental finding of a 1.3 cms left adrenal nodule. An episode of diverticulitis had prompted an abdominal CT scan which revealed these findings. The patient denied any symptoms including hematuria, weight loss, episodic spells of dizziness, palpitations, sweating or headaches. Vitals and physical exam were otherwise unremarkable. Biochemical testing revealed plasma metanephrines of 38pg/ml(0-62), plasma normetanephrines of 62pg/ml(0-145), 24-hour-urine norepinephrine of 148ug(1-135), 24-hour-urine dopamine of 1778ug(0-510) with 8 am-serum-cortisol levels at 2.34ug/dl(5-22) . Adrenal protocol CT scan revealed a 1.4 cms left adrenal adenoma, regular borders with >50% washout at 10 minutes. Although dopaminomas have significant malignant potential, based on above the incidentaloma was thought to be benign. A diagnosis of Von-Hippel-Lindau was initially entertained until the patient underwent an uncomplicated right partial nephrectomy with pathology revealing a benign oncocytoma. CONCLUSION: Dopaminomas, apart from being extremely rare, could be missed as they are not routinely included in the workup of an adrenal mass. They could cause hypotension and/or bradycardia. Management differs significantly in terms of pre and post-op management from classic pheochromocytomas if adrenalectomy is to be pursued. Alpha and beta blockade isn’t required as dopamine acts via different receptors. Due to the malignant potential, follow up of dopamine levels and imaging should be done. Definitive treatment is surgery. Ref: Poirier É., Thauvette D., Hogue J.-C. Management of exclusively dopamine-secreting abdominal pheochromocytomas. Journal of the American College of Surgeons. 2013;216(2):340-346. doi: 10.1016/j.jamcollsurg.2012.10.002