Thompson LDR.
Pathol Case Rev 2005;10 (5): 243-25.
Pheochromocytomas are tumors arising from the chromaffin cells of the adrenal medulla. They are equivalent to paragangliomas in other anatomic sites. They are uncommon neoplasms and most are sporadic, although 10% are described in syndromes, another 10% are bilateral (usually syndrome associated), and about 10% are malignant. They develop in both genders and peak in the fourth to fifth decades, although familial tumors occur at a younger age. Patients present clinically with the pharmacologic effects of excess catecholamines, manifested by episodic, postural, paroxysmal and/or labile hypertension, headaches, diaphoresis, palpitations, chest pain, and anxiety. Radiographic studies with nucleotide scans are often diagnostic. Malignant pheochromocytomas have historically required the presence of metastatic tumor to confirm the diagnosis of a malignant neoplasm. However, a series of histologic features, when used in conjunction with laboratory findings, radiographic findings, macroscopic features, and immunohistochemical results, can help to prospectively diagnose malignant heochromocytoma. These features include invasion, large nests or diffuse growth (loss of Zellballen architecture), focal or confluent necrosis, high cellularity, tumor cell spindling, cellular monotony, increased mitotic figures, atypical mitotic figures, profound nuclear pleomorphism, and hyperchromasia. Overall, the patient prognosis for benign pheochromocytoma is excellent, although that for malignant pheochromocytoma is intermediate, with surgery achieving the best clinical result of about 75% 5-year survival. Separation from benign pheochromocytoma and adrenal cortical neoplasms is important as the management is different.
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