Pheochromocytoma

Excerpt

A pheochromocytoma is a rare tumor originating from chromaffin cells in the adrenal medulla. Pheotochromocytomas clinical manifestations result from excessive catecholamine secretion. Catecholamines are a group of hormones and neurotransmitters crucial for regulating homeostasis and managing the body's response to stress. These chemicals are primarily produced by the adrenal gland and nerve tissue, including the brain. The principal catecholamines are dopamine, norepinephrine, and epinephrine.

Pheochromocytoma is a neoplasm that can be either benign or malignant and is often associated with familial syndromes such as neurofibromatosis type 1 (NF1), multiple endocrine neoplasia type 2 (MEN2), and von Hippel-Lindau (VHL) disease. In addition, sporadic cases are also significant, as they are among the most commonly overlooked causes of secondary hypertension (see Image. Gross Specimen of a Giant Pheochromocytoma).

The clinical manifestations of these tumors are primarily due to the excessive secretion of catecholamines. Tumors that arise from extra-adrenal chromaffin cells are known as paragangliomas, and both types are often studied together as neuroendocrine tumors due to their similar characteristics. Pheochromocytomas account for 80% to 85% of these tumors, while sympathetic paragangliomas account for 15% to 20%. Although most pheochromocytomas are benign, a small percentage can be malignant.

In the past, pheochromocytomas were primarily identified during evaluations for secondary hypertension. However, they are now increasingly found as incidental findings on abdominal imaging conducted for other conditions or through surveillance screening in individuals with known genetic disorders.

Pheochromocytomas generally exhibit a predominant type of catecholamine production. Around half primarily secrete epinephrine with varying levels of norepinephrine. Others, including sympathetic paragangliomas, mainly produce norepinephrine with dopamine as a by-product. Dopamine production is considered an independent predictor of malignancy, likely due to its role in promoting angiogenesis.