Diagnostic management of benign and malignant pheochromocytoma.

As rare and thus often overlooked hormone-secreting tumors, pheochromocytomas pose a particular diagnostic challenge. Difficulties involve biochemical confirmation, localizing, and detection of malignancy. Measurement of free plasma metanephrines, genetic testing and specific imaging procedures--such as MIBG and octreotide scintigraphy or fluorodopamine PET--represent a considerable progress, and the management of benign pheochromocytomas has become very effective. However, a comparable improvement in the prognosis of malignant chromaffin cell tumors, which occur in approximately 10-15% of all cases, has not yet been achieved. Here, telomerase catalytic subunit (hTERT) activity and heat shock protein 90 expression could serve both as molecular markers allowing an earlier diagnosis of malignancy and as therapeutic targets. Familial syndromes should be considered both in benign and malignant pheochromocytoma, and should be tested for prior to surgery in selected patient groups.