Pheochromocytoma

Maria E. Ferris, MD, MPH

Epidemiology

• Mean Age in children: 11 years

• Male 2:1 female

• Bilateral in 20% of cases

• 35 Malignant

PATHOLOGY

• It is a tumor of neuroendocrine origin first described by Frankel in 1886.

• In the 5th gestational week, neuroblasts migrate from the thoracic neural crest to form the sympathetic chains and preaortic ganglia (thought to be the precursors of neuroblastomas and ganglioneuromas.

Pathology (2)

• In the 7th week, a second migration of cells (chromaffin cells) occurs to form the adrenal medullae to: – the sympathetic ganglia, the vagus nerve, paraganglia of the

carotid arteries, the arch of the aorta, and the abdominal aorta.

– Less commonly to the wall of the urinary bladder, the prostate, behind the liver, the hepatic and renal hila, and near the rectum and the gonads.

• Pheochromocytomas and paragangliomas arise from these chromaffin cells.

Nomenclature

• Paraganglioma is any extra-adrenal tumor of the paraganglion system.

• Tumors in the head, neck, and paravagal region are usually nonfunctioning.

• Tumors around the aorta and sympathetic chain and visceral tumors, such as bladder tumors, usually elaborate catecholamines

Tumor Location

• 50% arise in the adrenal medulla.

• Most extra-adrenal pheochromocytomas (functional paragangliomas) occur in the abdomen along the great vessels -most commonly in the upper periaortic region from the diaphragm to the lower poles of the kidneys-

• Extra-adrenal tumors may also occur at the base of the brain, in the chest (including the heart and pericardium), or paratesticularly

Characteristics

• Size from 2 to 3600 g. and are typically not encapsulated.

• Microscopically, they are composed of nests or cords of polyhedral cells separated by a fibrovascular stroma. Nuclear pleomorphism does not correlate with malignant behavior

Malignancy

• Malignancy is Dx’d clinically based on the presence of extensive local invasion or metastatic disease.

• Metastases must be distinguished from multifocal tumors occurring elsewhere in areas of neural crest tissue.

Presentation and Dx

• Usualc/o related to catecholamine production.

• Patients have stores of catecholamines in sympathetic nerves & norepinephrine released from these terminals has easier access to receptors on the effector cells.

Presentation and Dx (2)

• The catecholamine-induced symptoms are mediated by the normal sympathetic neural pathway and not primarily by serum catecholamines.

• Any direct stimulus to the sympathetic nervous system can induce a crisis without a large rise in serum catecholamine levels.

• Blood pressure may sometimes be normal despite high serum levels of catecholamines.