the tumor produces catecholamines , such as norepinephrine and epinephrine , and leads to well - known clinical symptoms , such as hypertension , headache , sweating , palpitation , and orthostatic hypertension . it is usually found at extra - adrenal sites and is diagnosed as a subtype of paraganglioma . the high dopamine level in this tumor is caused by a deficiency in dopamine - beta - hydroxylase , which converts dopamine to norepinephrine . for this reason , this tumor differs from classic pheochromocytomas in many respects , not only in its clinical features but also in its oncologic aspect . only two original articles and five case reports have reported the occurrence of dopamine secreting paragangliomas in the retroperitoneum around the adrenal glands [ 2 - 8 ] . we report this interesting case and establish clinical concepts for this rare tumor by reviewing the related literature . a 26-year - old korean woman was referred after the accidental detection of an adrenal mass in her right side . she had no hypertension , palpitation , sweating , headache , flank pain , or mass upon palpation of her abdomen . on physical examination , her blood pressure was 110/90 mmhg and her heart rate was 90 beats / min . the results of laboratory tests , including a complete blood count and liver and renal function tests , were all unremarkable . serum norepinephrine and epinephrine levels were normal but the dopamine level was high ( 425 ng / l ) . analysis of a 24-hour urine sample revealed marked elevation of the urinary dopamine level ( 1,565.3 g / day ) but normal levels of vanillylmandelic acid ( vma ) , norepinephrine , epinephrine , metanephrine and normetanephrine . computed tomography results showed a 4.3  3.2 cm hypervascular mass on the right adrenal gland with an early washout enhancement pattern . 1 ) . magnetic resonance imaging revealed a 2.8 cm sized tumor that was located in the right periadrenal area and that abutted against the adrenal gland laterally and ivc medially ( fig . 2 ) . our preoperative diagnosis was a dopamine producing paraganglioma in the right retroperitoneum . hand - assisted laparoscopic right adrenalectomy was performed because of the firm attachment of the tumor to adjacent structures . her blood pressure was continuously normal and there were no fluctuations in vital signs during the operation . it was well encapsulated , homogenous and had a yellowish cut - surface with some internal hemorrhagic spots . microscopic diagnosis was a neuroendocrine tumor whose clinical manifestations were consistent with those of a paraganglioma . an immunohistochemical study showed that the tumor was positive for neuroendocrine markers such as cd-56 , synaptophysin and chromogranin . the tumor had a ki-67 index of less than 1 percent and was negative for s-100 ( fig . her 24-hour urine dopamine level returned to normal ( 388.4 g / day ) after the operation . her general condition was good and there was no recurrence during a 10-month follow - up . among the many types of paraganglioma , an exclusively dopamine producing type is extremely rare . only seven cases are listed in the worldwide database and no case has ever before been reported in south korea [ 2 - 8 ] . the exclusive production of dopamine can be ascribed to a deficiency in dopamine -hydroxylase which converts dopamine to norepinephrine in the catecholamine biosynthesis pathway beginning with tyrosine . because of the abnormal catecholamine synthesis pathway , the levels of dopamine and its end product , homovanillic acid ( hva ) , are increased , whereas the levels of norepinephrine , epinephrine and their end product , vma , are decreased . in consequence , the clinical presentation of this tumor is different from that of a classical pheochromocytoma that secretes norepinephrine and epinephrine . there is an absence of hemodynamic changes or so - called paroxysmal symptoms that are usually found in patients with catecholamine secreting pheochromocytoma . as a result , the patients with exclusively dopamine producing paraganglioma are mostly asymptomatic at initial diagnosis . some constitutional symptoms such as fever , malaise , weight loss or diarrhea may occur as a result of the increased circulating dopamine level . because paragangliomas tend to grow larger than adrenal pheochromocytomas , some patients experience vague abdominal pain or experience a palpable abdominal mass [ 4 - 8 ] . the asymptomatic features make it difficult for clinicians to detect the tumor at an early stage . detection is even more challenging to physicians working in institutes without routine screening procedures for the detection of catecholamine and dopamine . differential diagnosis can be achieved by measuring the dopamine levels in serum and 24-hour urine samples . clinicians should not rule out the possibility of this rare tumor when evaluating adrenal masses with normal serum norepinephrine , epinephrine and urinary vma levels , even if the radiologic images strongly suggest a pheochromocytoma . hand - assisted laparoscopic surgery has been adapted for the removal of large tumors and for the rescue of operative procedures in complicated cases of laparoscopic surgery . to minimize surgical mortality caused by hypertensive crisis during the manipulation of the tumor , preoperative administration of a -blocker is essential for norepinephrine and epinephrine producing pheochromocytomas . however , -blocker treatment is contraindicated for exclusively dopamine secreting paraganglioma because it can cause profound cardiovascular collapse after surgery , and can even result in death following a hypotensive crisis . there are two subtypes of dopamine receptors ; the d1 receptor , which relaxes smooth muscles in blood vessels , and the d2 receptor , which inhibits noradrenaline release from postganglionic sympathetic neurons . these two effects could explain the pre - operative hypotension in dopamine secreting tumor patients . blood pressure is sometimes elevated after the removal of this tumor presumably because of the same mechanism . dopamine secreting paragangliomas are more likely to present malignant features than classic catecholamine secreting type paragangliomas or pheochromocytomas . this rare tumor tends to be diagnosed in patients who are asymptomatic , and the tumor is detected later than tumors that secrete norepinepnrine , epinephrine or both . concerning the biochemical features , one report suggests that the decreased activity of dopamine -hydroxylase results in poor differentiation of this tumor , which may explain why the dopamine - secreting type shows advanced malignant features . elevated dopamine or hva levels in 24-hour urine ( > 120 nmol / g ) is correlated with large tumor size and malignant potential . extra - adrenal location , a tumor weight of more than 80 g , dna aneuploidy or triploidy and persistent postoperative hypertension have also been reported as risk factors for malignant pheochromocytoma . because of the rarity of this tumor , there are no definite criteria for evaluating its malignant potential . in conclusion , lack of clinical symptoms and the rarity of this tumor can lead to the lack of , or a delay in diagnosis . in addition to radiologic imaging , dopamine assays in serum and 24-hour urine collection are useful diagnostic tests .