Pheochromocytoma (pheo) is a rare tumor of the central part of the adrenal gland. As described on other pages, this portion of the adrenal gland is called the medulla. It makes epinephrine (adrenalin) and other vasoactive hormones call catecholamines. These hormones control the bodies’ “flight or fight” reflex. Tumors developing here may be malignant, but are usually benign.
“Pheos” over produce these hormones in an unpredictable and unregulated manner. This results in a unique clinical syndrome that includes episodic heart palpitations, headaches and sweating, accompanied by severe high blood pressure. Some patients experience tremors and anxiety. The elevated blood pressure maybe sustained or episodic.
The diagnosis of a pheo involves the patient having the symptoms described above accompanied by significantly elevated blood pressure. Biochemical testing is done to detect elevated levels of catecholamines and their breakdown products. This can be problematic, because these levels may vary a lot in the normal situation as well as when a pheo is present. Usually, we use a 24 hour collection of urine to measure catecholamines breakdown products called metanephrines and VMA. The diagnosis may be tricky because these hormones may not be consistently secreted and many common prescription medications may influence the results. For example, a class of medications called beta-blockers (used to treat high blood pressure) may result in false elevation of these hormones (a false positive result). While calcium channel blockers (also used to treat high blood pressure) may falsely reduce the measured catecholamines (a false negative result). Therefore, evaluation by an experienced physician or endocrinologist is important. In uncertain situations, a carefully controlled blood test for metanephrines may be helpful. Other more complicated blood testing (clonidine suppression test) may be helpful but is not commonly used.
Usually, in suspicious but unproven cases, we obtain an I-131 MIBG whole body scan. This scan reliably shows the tumor position as well as confirms it as a pheochromocytoma. Additionally, it may show secondary tumors or evidence of metastatic disease.
Once the diagnosis is made, tests to locate the tumor are performed. We use MRI, I-131 MIBG scan, and CT scans to locate the tumor, check for evidence of multiple tumors and to find evidence of metastatic disease. 90% of pheos are in the adrenal glands. 10% of cases show tumors on both adrenal glands. 10% of tumors may be found outside the adrenal glands. 10% are malignant. Additionally, other screening test are done to ensure that the patient doesn’t have an inherited syndrome which may cause tumors in other endocrine organs( MEN type 2 ).
After the diagnosis is confirmed, the tumor is located and extent of disease determined, an operative approach is organized. These tumors secrete hormones that may cause dangerously high blood pressure during surgery. The effect of these hormones must be blocked to allow the tumor to be removed as safely as possible. This is discussed on the pre-op care for adrenalectomy page.
Once the patient is adequately prepared the tumor is removed laparoscopically. The details of this are discussed on the laparoscopic adrenalectomy page. After surgery, the patient is observed in the intensive care unit for 24 to 48 hours. Variations in blood pressure may occur and careful monitoring after surgery is important. Once the patient is stable off medication for high blood pressure they are discharged. Patients are seen about 10 days post-op and then follow-up usually with an endocrinologist is arranged. About 10% of pheos are malignant. It can be difficult to be certain about this even with careful examination of the tumor by a pathologist. Generally, the larger the tumor the more likely it is to be malignant. Because of this uncertainty, patients who have had pheos removed should be monitored regularly for recurrent disease. View a video of a laparoscopic adrenalectomy for a pheochromocytoma.