Pheochromocytomas are neuroendocrine tumors that produce an excessive amount of catecholamines. This catecholamine excess presents as a wide range of systemic effects. Pheochromocytomas have an incidence of 2–8 cases per 1,000,000 patients. In patients who are already diagnosed with hypertension, pheochromocytomas are found to be the cause in 0.1%–0.6% of these patients. A significant percentage (25%–50%) of patients with pheochromocytoma who die in a hospital admission do so perioperatively.
Most of these tumors are unilateral, located on the adrenal glands and on the right side. In adults, 10% are bilateral, and extra-adrenal. In children, 25% are bilateral and extra-adrenal. These conditions can present as an isolated disorder or as part of two autosomal dominant conditions, multiple endocrine neoplasia (MEN) syndromes (MEN IIa, MEN IIb). Metastatic disease occurs in 3%–36% of patients diagnosed with pheochromocytoma.
The diagnosis begins with a thorough clinical history. Patients will often describe sweating, headaches, fainting, or palpitations. They may demonstrate hypertension, orthostatic hypotension, arrhythmias. The combination of a headache, sweating, and hypertension should raise suspicions for an underlying pheochromocytoma. Past anesthetics that provoke hypertension or tachydysrhythmias should also raise concern.
If the patient demonstrates several of these symptoms, confirmatory blood and urine tests should be performed. The urine tests measure the level of catecholamines and their metabolites. Diagnosis relies on measuring the levels of catecholamines and their byproducts. Vanillylmandelic acid, a catecholamine metabolite, is the most specific test. Abdominal CT scans are the most sensitive.
Medical management should be instituted immediately if a pheochromocytoma is diagnosed. The goal is minimize paroxysms, periods of cardiovascular instability. In an acute hypertensive crisis, surgery is not well tolerated, and thus medical management is the first line of treatment. Although an adrenalectomy is a definitive therapy, it is not always possible. Widespread metastases preclude patients from surgery.
For these patients, adjunctive therapies are generally palliative. If compressing on local structures causes pain, external beam therapy, cryoablation, or radiofrequency therapy can be attempted. Systemic chemotherapy can help reduce the rate of growth of these tumors, although they are accompanied by their own side effects. Experimental therapies with tyrosine kinase inhibitors and radiolabeled somatostatin analogs have demonstrated mixed effects and warrant further study.
PREOPERATIVE ASSESSMENT AND OPTIMIZATION
The preoperative evaluation should address a number of significant questions:
Is the pheochromocytoma an established diagnosis? If the diagnosis is known, all elective cases should be delayed until the pheochromocytoma is addressed first. If its presence is unknown prior to an operation, it will likely manifest itself as a history of cardiovascular instability or exaggerated swings in blood pressure.
Is it unilateral, bilateral, or locally metastasized? The location of the tumor will determine positioning and the surgical approach. A laparoscopic procedure is preferred over the open procedure, but ...