Pheochromocytoma: new concepts and future trends

Diagnosis and evaluation of secondary hypertension

Although patients with secondary hypertension comprise only a small percentage of those with elevated blood pressure, this subgroup should not be ignored. In many cases, correcting the cause of secondary hypertension can lead to a cure, thus avoiding the need for long-term medical therapy, with its attendant risks and economic toll. Moreover, effective treatment of secondary hypertension can prevent chronic complications, such as left ventricular hypertrophy and coronary artery disease, which markedly increase morbidity and mortality. Nearly all forms of secondary hypertension are related to decreased renal function and/or derangement of hormonal balance or secretion. If hypertension is secondary to chronic renal failure of any etiology, it can be recognized from biochemical assays for blood urea nitrogen and creatinine.

Hypertension in patients with pheochromocytoma

Adrenal-dependent hypertension syndromes are uncommon forms of hypertension. They include primary aldosteronism, pheochromocytoma, Cushing"s syndrome, and congenital adrenal hyperplasia. Pheochromocytomas are the cause of hypertension in 0.1% to 0.2% of hypertensive patients. Excess catecholamine release and other neural and humoral mechanisms contribute to the pathophysiology of hypertension. Patients with pheochromocytomas have a potentially curable cause of endocrine hypertension and, if undetected, pheochromocytomas confer a high risk for morbidity and mortality, especially during surgical procedures and pregnancy. All patients with incidental adrenal tumors, regardless of tumor size, should be biochemically screened for pheochromocytoma (especially before resection or needle biopsy) to avoid precipitation of a lethal hypertensive crisis.

Clinical and genetic characterization of pheochromocytoma in von Hippel-Lindau families: comparison with sporadic pheochromocytoma gives insight into natural history of pheochromocytoma

PURPOSE

Families with von Hippel-Lindau disease have variable risk of pheochromocytoma. Patients with von Hippel-Lindau disease and pheochromocytoma identified by screening can have no characteristic signs or symptoms. Families with von Hippel-Lindau disease were screened and followed to describe the natural history of von Hippel-Lindau pheochromocytoma, and to correlate these findings with von Hippel-Lindau germline mutation.

MATERIALS AND METHODS

Between 1988 and 1997, 246 individuals with von Hippel-Lindau disease were identified (von Hippel-Lindau group). Between August 1990 and June 1997, 26 consecutive patients with sporadic pheochromocytoma were evaluated (sporadic group).

RESULTS

A total of 64 patients with von Hippel-Lindau disease had manifestations of pheochromocytoma, including 33 newly diagnosed during screening at the National Institutes of Health and 31 previously treated (93 adrenal and 13 extra-adrenal pheochromocytomas). Germline von Hippel-Lindau gene missense mutation was associated with extra-adrenal pheochromocytoma, younger age at presentation and the only patient with metastases. Of the 33 newly diagnosed patients with von Hippel-Lindau disease 4 had pheochromocytoma 2 times (37 pheochromocytomas) during followup. Of these pheochromocytomas 35% (13 of 37) were associated with no symptoms, normal blood pressure and normal catecholamine testing. Comparison of urinary catecholamines in the von Hippel-Lindau and sporadic groups demonstrated increased epinephrine, metanephrines and vanillylmandelic acid in the sporadic group. Analysis of urinary catecholamine excretion in the von Hippel-Lindau and sporadic groups together demonstrated a correlation between tumor size, and urinary metanephrines, vanillylmandelic acid, norepinephrine, epinephrine and dopamine. In 12 patients without signs or symptoms of pheochromocytoma 17 newly diagnosed pheochromocytomas were followed for a median of 34.5 months without morbidity. Median tumor doubling time was 17 months.

CONCLUSIONS

Von Hippel-Lindau gene missense mutation correlated with the risk of pheochromocytoma in patients with von Hippel-Lindau disease. These findings support a von Hippel-Lindau disease clinical classification, wherein some families are at high risk for manifestations of pheochromocytoma. Von Hippel-Lindau disease pheochromocytomas identified by screening were smaller and less functional than sporadic pheochromocytomas.

Successful outcomes in pheochromocytoma surgery in the modern era

PURPOSE

We describe our experience with surgical management, complications and treatment outcome of histologically confirmed pheochromocytoma.

MATERIALS AND METHODS

The records of 113 patients who underwent surgical excision of pheochromocytoma were reviewed and assessed for preoperative medical treatment, intraoperative findings, postoperative hospitalization and complications.

RESULTS

There were no surgical mortalities. Average length of stay in the intensive care unit was 1.2 days. There were only 6 major cardiovascular complications all of which occurred in patients who received preoperative medications, including 5 with alpha blockade. Patients receiving no preoperative alpha blockade required an average of 956 cc less in total intraoperative fluids, which approached statistical significance, and 479 cc less fluids on postoperative day 1, which was statistically significant.

CONCLUSIONS

Preoperative alpha-adrenergic blockade is not essential in pheochromocytoma patients. Calcium channel blockers are just as effective and safer when used as the primary mode of antihypertensive therapy. Surgery for pheochromocytoma is safe in the modern era.

Pheochromocytoma in dogs and cats

Pheochromocytomas are endocrine tumors arising from chromaffin cells (pheochromocytes) of the adrenal glands in dogs and cats. The clinical symptomatology produced results from the direct presence and space-occupying nature of the tumor, or the secondary presence of excessive amounts of excreted catecholamines. Diagnosis and management of pheochromocytomas remain great challenges for veterinary clinicians. The diagnosis is based on the results of supporting routine lab evaluation, blood-pressure determinations, selected biochemical and pharmacologic tests, and a number of imaging techniques. Surgical extirpation continues to be the only definitive treatment for the pheochromocytoma. Medical therapy is used to stabilize the metabolic and cardiovascular states of the patient in a preoperative and surgical setting as well as to manage chronic long-term effects of excess catecholamines in patients with inoperable or metastatic disease.

Pheochromocytoma

OBJECTIVE

To characterize the symptoms associated with pheochromocytoma and discuss the diagnosis and management of this tumor.

METHODS

We review the clinical manifestations in patients with pheochromocytoma, the biochemical and imaging studies recommended for diagnosis and localization of the tumor, and the available strategies for treatment.

RESULTS

Pheochromocytoma is a tumor of chromaffin cells that originates in either the adrenal medulla or the extra-adrenal sympathetic tissues. It is usually unilateral and benign. Frequent initial symptoms include headache, sweating, and palpitations, with or without increased blood pressure. In many patients, hypertension is accelerated during a paroxysm. Pheochromocytoma may also occur as a part of multiple endocrine neoplasia type IIA and B. Several common syndromes, such as panic disorders and hyperthyroidism, may mimic pheochromocytoma; however, pheochromocytoma should be suspected in the presence of hypertension, tachycardia, and throbbing headache, especially occurring as paroxysmal episodes. The physiologic diagnosis of pheochromocytoma is established by biochemical tests of levels of plasma and urinary catecholamines or their metabolites (or both). In most patients, anatomic localization is achieved with computed tomography or magnetic resonance imaging, metaiodobenzylguanidine scintigraphy, labeled somatostatin scans, or positron emission tomography. The management preferentially includes surgical removal of the pheochromocytoma after preparation with appropriate medical therapy to avoid hypertensive crisis during the perioperative period. Patients with contraindications to a major surgical procedure or with malignant pheochromocytoma and metastatic disease, however, may be treated with multiple drugs--for example, alpha- and beta-adrenergic blockers and direct vasodilators to neutralize the effects of high levels of circulating catecholamines and alpha-methyl-metatyrosine to inhibit catecholamine synthesis.

CONCLUSION

The presence of suggestive clinical features in patients with hypertension should prompt clinicians to undertake appropriate diagnostic testing because surgical resection of a pheochromocytoma will yield a cure in many cases.

Secondary hypertension: evaluation and treatment

Most patients with hypertension in the United States have essential (primary) hypertension (95%), the cause of which is unknown. The remaining 5% of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic process of which are known. Internists and other primary care physicians refer to this as treatable or curable hypertension, because the hypertension can be managed or even controlled with medications. Similarly, the condition is called surgical hypertension by surgeons in the belief that once the cause is determined and identified, surgical intervention will result in cure of hypertension. Secondary causes of hypertension include renal parenchymal disease, renovascular diseases, coarctation of the aorta, Cushing's syndrome, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism, and hyperparathyroidism. Occasionally included in this category are alcohol- and oral contraceptive-induced hypertension and hypothyroidism, but these conditions are not discussed herein. The evaluation of secondary hypertension is of interest and can bring together different facets of anatomy, physiology, pharmacology, and radiology in the medical and surgical treatment of these disorders. Despite enthusiasm that can be generated in the evaluation of these conditions, evaluation can be expensive and should not be conducted for all patients with hypertension. Features that aid in the diagnosis of secondary hypertension include the following: 1. Onset of hypertension before the age of 20 or after the age of 50 years. The presence of hypertension at a young age may suggest coarctation of the aorta, fibromuscular dysplasia, or an endocrine disorder. Hypertension found for the first time after the age of 50 years may suggest the presence of renovascular hypertension caused by atherosclerosis. 2. Markedly elevated blood pressure or hypertension with severe end-organ damage, as in grade III or IV retinopathy. These findings suggest the presence of renovascular hypertension or pheochromocytoma. 3. Specific body habitus and ancillary physical findings. For example, truncal obesity and purple striae occur with hypercortisolism, and exophthalmos is associated with hyperthyroidism. 4. Resistant or refractory hypertension (poor response to medical therapy usually necessitating use of more than three antihypertensive medications from three different classes). 5. Specific biochemical test that suggest the existence of certain disorders, such as hypercalcemia in hyperparathyroidism, hyperglycemia in Cushing's syndrome and pheochromocytoma, and unprovoked hypokalemia with renin-producing tumors, primary hyperaldosteronism, or renin-mediated renovascular hypertension. 6. Other characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease). A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation.

Dihydroxyphenylglycol in pheochromocytoma: its diagnostic use for norepinephrine dominant tumor

PURPOSE

To discern whether the 3,4-dihydroxyphenylglycol produced in adrenal medulla is associated with altered urinary excretion, we compared the tissue and urinary levels of this catecholamine metabolite, epinephrine and norepinephrine in 23 patients with pheochromocytoma and 26 subjects with renal cell carcinoma.

MATERIALS AND METHODS

Tissue and urine concentrations of dihydroxyphenylglycol, epinephrine and norepinephrine were determined by catechol-O-methyl-transferase-based radioenzymatic method and high performance liquid chromatography with electrochemical detection.

RESULTS

Contents of dihydroxyphenylglycol, epinephrine and norepinephrine in pheochromocytomas were higher than those in normal adrenal medullae. Removal of pheochromocytomas lowered urinary excretion of these catecholamines and dihydroxyphenylglycol. Norepinephrine content correlated closely with dihydroxyphenylglycol content in normal adrenal medullae and pheochromocytomas but not with epinephrine content in either tissue. Contents of norepinephrine and dihydroxyphenylglycol correlated significantly with urinary norepinephrine excretion and dihydroxyphenylglycol excretion in patients with pheochromocytoma but not in subjects with renal cell carcinoma. The norepinephrine-to-dihydroxyphenylglycol ratio in a 24-hour preoperative urine collection from patients with pheochromocytoma was higher than that from subjects with renal cell carcinoma, which was almost similar to that of epinephrine dominant pheochromocytomas.

CONCLUSIONS

Our study suggests that dihydroxyphenylglycol in urine in subjects with renal cell carcinoma is predominantly of a neuronal origin and urinary dihydroxyphenylglycol in patients with pheochromocytoma is of tumor origin. A high level of norepinephrine-to-dihydroxyphenylglycol ratio in urine can be used to determine the diagnosis of the norepinephrine dominant type pheochromocytoma. Measurement of at least a few markers is preferable for precise biochemical diagnosis of pheochromocytoma.

Pheochromocytomas, multiple endocrine neoplasia type 2, and von Hippel-Lindau disease

BACKGROUND

Pheochromocytoma is a feature of two disorders with an autosomal dominant pattern of inheritance--multiple endocrine neoplasia type 2 (MEN-2) (with medullary thyroid carcinoma and hyperparathyroidism) and von Hippel-Lindau disease (with angioma of the retina, hemangioblastoma of the central nervous system, renal-cell carcinoma, pancreatic cysts, and epididymal cystadenoma). The frequency of these syndromes in patients with pheochromocytoma is not known.

METHODS

In an unselected group of patients with pheochromocytoma, we performed pentagastrin tests, parathyroid hormone assays, computed tomography (CT) or magnetic resonance imaging (MRI) of the brain, ophthalmoscopy, CT imaging of the abdomen, and ultrasonography of the testes. We also screened members of families with MEN-2 or von Hippel-Lindau disease for pheochromocytoma by measuring plasma and urine catecholamines and plasma chromogranin A and by performing abdominal ultrasonography, CT and MRI, and metaiodobenzylguanidine scintigraphy.

RESULTS

Nineteen of 82 unselected patients with pheochromocytomas (23 percent) were carriers of familial disorders; 19 percent had von Hippel-Lindau disease and 4 percent had MEN-2. Prospectively, in 36 of 79 subjects at risk for pheochromocytoma (46 percent), 42 unsuspected pheochromocytomas were found. Overall, there were 130 patients with 185 pheochromocytomas; 43 had von Hippel-Lindau disease, 24 had MEN-2, and 63 had sporadic tumors. The patients with familial and those with sporadic pheochromocytomas differed in mean age at diagnosis (32 vs. 46 years, P < 0.001), multifocal localization (55 vs. 8 percent, P < 0.001), and cancer (0 vs. 11 percent, P = 0.005); but not in the frequency of extraadrenal tumors (24 vs. 16 percent). Thirty-eight percent of carriers of von Hippel-Lindau disease and 24 percent of carriers of MEN-2 had pheochromocytoma as the only manifestation of their syndrome.

CONCLUSIONS

All patients with pheochromocytomas should be screened for MEN-2 and von Hippel-Lindau disease to avert further morbidity and mortality in the patients and their families. All patients in families with MEN-2 or von Hippel-Lindau disease should be screened for pheochromocytoma, even if they are asymptomatic.