Dopamine-secreting pheochromocytoma: an unrecognized entity? Classification of pheochromocytomas according to their type of secretion.

A pheochromocytoma that exclusively secretes dopamine (DA) rather than predominantly DA among a blend of catecholamines is as yet unreported. Of the 50 patients with pheochromocytoma who have undergone surgery, 32 underwent treatment within the last 5 years (when DA assay has been available). One half of these patients (15/32) exhibited DA secretion either in mixed catecholamines (12 patients) or exclusively (three patients). All three patients with exclusive DA-secreting tumors were normotensive. Without hypertension, the clinical investigation was a diagnostic challenge (unexplained cough or flank mass with inflammatory features). All three tumors were malignant and two were ectopic. Five of the 12 patients with mixed catecholamine-secreting tumors whose secretions included DA were hypertensive. Five other patients had flank mass and one had an unexplained cough. Tumors were rather large, and three of the tumors with mixed secretion were ectopic. Of the 12 patients, seven had tumors that were judged to be malignant. Three patients exhibited a dramatic decrease in blood pressure under alpha-blockade, which was not used in subsequent cases. Predominant or exclusive secretion of DA would explain the lack of hypertension due to its antiadrenergic action that inhibits the vasoconstrictive effects of other amines. Hypertension in patients with pheochromocytoma might depend on the ratio of DA/noradrenaline + adrenaline.