Case Presentation: 42 year old male presented to the hospital with non-exertional left-sided chest pain that was radiating to his left jaw. His past medical history was significant for gastro-esophageal reflux disease and generalized anxiety disorder. He had a one year history of palpitations, headache, and sweating associated with minimal blood pressure fluctuations. These episodes lasted few minutes to half an hour and occurred two to three times per week. Initial blood pressure was 113/73 mm Hg and pulse rate was 78 bpm. Complete blood count, random blood sugar, blood urea, troponin levels, chest x-ray, and EKG were within normal limit. CT scan of abdomen showed a small right heterogeneously enhancing adrenal mass. 24-hour testing for urine metanephrine, normetanephrine, and dopamine were obtained. Urine 24-hour dopamine level was elevated at 1300 mcg/24h but metanenephrine and normetanephrine levels were in high normal range. Subsequent MRI and MIBG scan confirmed a small right adrenal mass. Phenoxybenzamine was not started due to concerns for hypotension given his blood pressure. Instead patient was started on metoprolol succinate 25 mg daily to help some of his symptoms during catecholamine surges. Patient was referred to a tertiary care hospital for possible surgical intervention.
Discussion: Only 9 cases of exclusively dopamine-secreting adrenal pheochromocytomas have been reported in literature. These tumors often lack classical symptoms of epinephrine and norepinephrine secreting tumors which can delay the diagnosis. Alpha-blocker treatment is contraindicated for dopamine-secreting pheochromocytomas because case reports have shown it can lead to cardiovascular collapse and hypotensive crisis. Surgical resection is indicated in dopamine-secreting tumors. This case highlights the importance of identifying the type of tumor in a patient with adrenal mass. Measurement of plasma or urinary dopamine should become part of routine workup in all patients presenting with suspected pheochromocytoma.
Conclusions: Our patient had an extremely rare dopamine secreting pheochromocytoma. This type of tumor lacks clinical symptoms that can lead to delay in diagnosis. In addition to dopamine assays in serum and 24-hour urine collection, radiological imaging is useful in diagnosis. Laparoscopic tumor removal is the treatment of choice when preoperative α-blocker cannot be given. Our patient was sent to a tertiary care center for a surgical intervention.