Internal Medicine

0521779407-17 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:57

Pheochromocytoma 1167

Imaging

■CT or MRI only after biochemical diagnosis confirmed

■CT and MRI have limited specificity due to high prevalence of inci-

dental adrenal mass

■CT of abdomen: pretreat with alpha-blockers to avoid aggravation

of hypertension that may occur during administration of IV CT con-

trast dye; 90% of pheochromocytoma localize to adrenals; 95% of

pheochromocytomas are intraabdominal

■MRI: On T2-weighted imaging, pheochromocytomas often appear

hyperintense

■Nuclear Medicine Studies

■For extraadrenal, extraabdominal, or metastatic pheochromocy-

tomas where CT or MRI nondiagnostic

■131-I-metalobenzylguanidine (MIBG) (a catechol precursor)

■111-Indium pentetreotide (labels neuroendocrine tissues expressing

somatostatin receptor)

differential diagnosis

■Catecholamine excess from nonpheochromocytoma source (drugs,

panic attacks, medical/surgical illness, spinal cord injury)

■Bilateral pheochromocytoma in 10% of cases, esp in setting of genetic

predisposition

■Extraadrenal pheochromocytoma (paraganglionoma): paraaortic,

bladder, thorax, head and neck, pelvis

management

What to Do First

■Initiate medical therapy prior to surgery

General Measures

■Avoid extremes of hypo/hypertension

■Avoid catecholamine-releasing agents

■Volume replacement

■Management of cardiovascular risk

specific therapy

■Alpha-adrenergic blockade:

➣Phenoxybenzamine until symptoms and BP controlled or titrated

to clinical parameters (nasal stuffiness, orthostatic hypotension)

➣Calcium channel blockers as alternatives to pheonoxybenza-

mine