The dominant clinical manifestation of pheochromocytoma is hypertension, observed in 90% of patients. Approximately two-thirds of patients with hypertension demonstrate paroxysmal episodes, which are described as an abrupt, precipitous elevation in blood pressure, associated with tachycardia, palpitations, headache, sweating, tremor, and a sense of apprehension. These episodes may also be associated with pain in the abdomen or chest, nausea, and vomiting. Isolated paroxysmal episodes of hypertension occur in fewer than half of patients; more commonly, patients demonstrate a chronic, sustained elevation in blood pressure punctuated by the aforementioned paroxysms. The elevations of blood pressure are induced by the sudden release of catecholamines that may acutely precipitate congestive heart failure, pulmonary edema, myocardial infarction, ventricular fibrillation, and cerebrovascular accidents. The cardiac complications have been attributed to what has been called catecholamine cardiomyopathy, or catecholamine-induced myocardial instability and ventricular arrhythmias. In some cases, pheochromocytomas secrete other hormones such as ACTH and somatostatin and may therefore be associated with clinical features related to the effects of these and other peptide hormones. The laboratory diagnosis is based on demonstration of increased urinary excretion of free catecholamines and their metabolites, such as vanillylmandelic acid and metanephrines. Isolated benign pheochromocytomas are treated with surgical excision. With multifocal lesions, long-term medical treatment for hypertension may be required.
Neuroblastoma is the most common extracranial solid tumor of childhood. These neoplasms occur most commonly during the first 5 years of life and may arise during infancy. Neuroblastomas may occur anywhere in the sympathetic nervous system and occasionally within the brain, but they are most common in the abdomen; a majority of these tumors arise in either the adrenal medulla or the retroperitoneal sympathetic ganglia. Most neuroblastomas are sporadic, although familial cases also have been described. These tumors are discussed in Chapter 7, along with other pediatric neoplasms.
Fig.20.45Photomicrographofpheochromocytoma,demonstratingcharac-teristicnestsofcellswithabundantcytoplasm.Granulescontainingcate-cholaminearenotvisibleinthispreparation.Itisnotuncommontofindbizarrecells(suchastheoneinthecenterofthisimage),eveninpheochro-mocytomasthatarebenign.
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The MEN syndromes are a group of inherited diseases caused by proliferative lesions (hyperplasias, adenomas, and carcinomas) of multiple endocrine organs. Like other inherited cancer disorders (Chapter 6), endocrine tumors arising in the context of MEN syndromes have certain distinctive features that are not shared with their sporadic counterparts:
These tumors occur at a younger age than that typical for sporadic cancers.
They arise in multiple endocrine organs, either synchronously (at the same time) or metachronously (at different times).
Even in one organ, the tumors often are multifocal.
The tumors usually are preceded by an asymptomatic stage of endocrine hyperplasia involving the cell of origin of the tumor (e.g., patients with MEN-2 almost universally demonstrate C cell hyperplasia in the thyroid parenchyma adjacent to medullary thyroid carcinomas).
These tumors are usually more aggressive and recur in a higher proportion of cases than similar endocrine tumors that occur sporadically.