Julia R. Fielding, M.D. Brigham and Women's Hospital, Harvard Medical School Boston, Massachusetts

Case 9: 43 Year-old Woman with Hypertension

A middle-aged woman presented to her primary care physician with hypertension and episodic sweating. She was referred to a urologist who obtained a 24 hour urinary vanillymandelic acid (VMA) which was elevated. CT scan was then performed (Figure 1) and (Figure 2). A nuclear medicine scan was also obtained (Figure 3).

The diagnosis is Extraadrenal Pheochromocytoma. Approximately 10% of pheochromocytomas are extraadrenal in location with the most common site being the sympathetic chain at the organ of Zuckerkandl, adjacent to the take-off of the inferior mesenteric artery. Both metaiodobenzylguanidine (MIBG) and octeotride can be used as radiotracers. MIBG is incorporated at the site of production of epinephrine and norepinephrine and enhances at sites of excess catecholamine excretion. In this case, octeotride was used. Octeotride is a somatostatin analog. Many hormonally active tumors have somatostatin receptors, therefore octeotride is not as specific as MIBG for the presence of pheochromocytoma.

Reference:

Lastoria S, et al. Comparison of labeled MIBG and somatostatin analogs in imaging neuroendocrine tumors. Q J Nucl Med 1995; 39: 145-149.