A 50-year-old, healthy-appearing man undergoes evaluation of persistent hypertension. Serum chemistries reveal hypokalemia (less than 3.2 mmol/L) and imaging studies reveal a unilateral adrenal mass. What is the likely diagnosis?
Primary aldosteronism, or Conn syndrome, is seen in about 1% of hypertensive patients. It is more common in middleaged individual and is usually associated with a single adenoma of the adrenal cortex. The hypertension is usually refractory to medical treatment, and is classically associated with hypokalemia, but may be seen in normokalemic individuals.
A 35-year-old woman undergoes an evaluation for infertility. She has gained almost 100 lb in the past year, is hypertensive, and is borderline diabetic. She also complains of easy bruising. Her serum chemistries are normal with the exception of an elevated glucose. Imaging studies reveal a unilateral adrenal mass. What is the likely diagnosis?
Cushing syndrome refers to any cause of hypercortisolism caused by either an adrenal source or exogenous administration of steroids. Cushing disease refers only to an adrenocorticotropic hormone (ACTH)-secreting adenoma of the pituitary gland. Cushing syndrome due to an isolated adrenal adenoma is far less common than hypercortisolism due to a pituitary adenoma, but adrenalectomy is curative for primary adrenal tumors or for adrenal hyperplasia that persists despite efforts to resect a pituitary tumor.
All of the following imaging techniques are useful to localize a pheochromocytoma EXCEPT:
Pheochromocytomas are solid tumors which appear on computed tomography ( CT) scan as soft tissue masses. They are detected with 85 to 95% accuracy, but it is important to avoid intravenous-contrast enhancement when a pheochromocytoma is suspected; intravenous contrast can provoke a hypertensive crisis due to release of catecholamines. MR is useful to identify pheochromocytomas, both because they identify soft tissue masses, but also because this tumor tends to enhance on T2-weighted images. Radio-labeled metaiodobenzylguanidine (MIBG) is taken up avidly by the pheochromocytoma because its structure is similar to norepinephrine. Therefore the MIBG scan can localize an occult tumor. Octreotide scans are not used for pheochromocytoma as the tumor does not overexpress somatostatin receptors.
Pheochromocytomas can secrete excess amounts of all of the following EXCEPT:
Extra-adrenal pheochromocytomas (also known as paragangliomas) secrete norepinephrine, because these sites lack the enzyme (phenylethanolamine N-methyltransferase) which converts norepinephrine to epinephrine. Adrenal pheochromocytomas secrete both epinephrine and norepinephrine as well as dopamine. Some pheochromocytomas secrete only dopamine, and patients with these tumors may be normotensive.
The preoperative preparation of a patient with pheochromocytoma should include all of the following EXCEPT:
The preoperative preparation of a patient with a catecholamine-secreting tumor includes alpha-hypertension, a beta-adrenergic blocker to prevent tachycardia, and volume replacement to avoid hypotension due to alpha- and betablockers. Steroids are not needed to prevent adrenal insufficiency.