What is the difference between malignant and benign pheochromocytoma?

Prognosis. Majority of pheochromocytomas are benign only about 10 % are malignant, one third ( 30 % ) out side adrenal gland tumors are malignant. With 50 % 5 yr survival, also show elivated levels of chromogranin a .
Histologically diff. Pheochromocytomas are virtually all benign under the microscope and are very rare.The annual incidence in the US is 3 to 8 cases per million. When the tumor is removed and examined by the pathologist seldom shows atypical or cancer cells. The other possibility is to find a person with metastatic disease associated to a pheochromocytomas which is probably very rare.