The only clinically significant hypertension due to circulating epinephrine of which we know is associated with pheochromocytoma. This is a tumor consisting of chromaffin tissue, producing epinephrine, and arising either in the adrenal medulla or in one of the many, widespread areas where chromaffin tissue is found during early life.
At first sight, we may seem to be dealing with a medical curiosity, for only 134 cases of this kind have been described since 1922, when Labbe1 first reported a case of paroxysmal hypertension due to a tumor of the adrenal medulla, but such cases are not so rare as the literature would indicate. In Smithwick's2 series of 1,000 hypertensive patients subjected to lumbodorsal sympathectomy, in which both adrenal glands were exposed in order to remove possible adrenal tumors, the incidence of pheochromocytoma was 0.5 per cent. This is probably less than the real incidence, since in a